April 22, 2025 • 40 mins
If you’ve been gardening for any amount of time, you’ve likely come across companion planting charts—maybe you’ve seen advice like “plant basil with tomatoes” or “marigolds repel all pests.” But how much of this is actually true?
Companion planting can mean a lot of things, depending on what our goal is. We can either be going for pest repelling properties, keeping weeds down, soil health benefits, or just enhancing flavors or saving space.
Today on Just Grow Something, we’re sorting fact from fiction. Some companion planting practices do have solid science behind them. But many claims are more anecdotal than evidence-based—and in some cases, well-intended pairings might even backfire. I’m looking at you marigolds. Let's dig in!
References and Resources:
Save 20% on your new own-root rose plant at HeirloomRoses.com with code JUSTGROW https://heirloomroses.com
Companion Planting: Fact or Fiction?: https://growappalachia.berea.edu/2019/04/01/companion-planting-fact-or-fiction/
Companion Planting & Botanical Pesticides: Concepts & Resources: https://attra.ncat.org/publication/companion-planting-resources/#4
Companion Planting | West Virginia University: https://extension.wvu.edu/lawn-gardening-pests/gardening/garden-management/companion-planting
Phytoremediation episode: https://justgrowsomethingpodcast.com/episode/focal-point-friday-are-sunflowers-good-or-bad-for-the-garden
IPM episode: https://justgrowsomethingpodcast.com/episode/integrated-pest-management-in-the-home-garden-ep-228
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
If you have been gardening for any amount of time, you have
likely come across companion planting charts.
Maybe you have seen advice that says plant basil with tomatoes,
or just general advice to plant marigolds with everything
because they repel pests. But how much of this is actually
true? Companion planting can mean a
(00:20):
lot of things. Depending on what our goal is.
We can either be going for pest repelling properties, or we
could be aiming to keep weeds down.
We might be looking for soil health benefits or just
enhancing flavors or saving space.
Today I'll just grow something. We are sorting fact from
fiction. Some companion planting
practices do have solid evidencebehind them, or I should say
(00:44):
solid science. But a lot of claims are more
anecdotal than evidence based. And in some cases we might be
doing some well intended pairings that may even backfire.
I'm looking at you marigolds. So we will talk about what the
research says about using specific plants to either deter
or attract pests, when companionplanting works and when it
(01:08):
doesn't, which plants shouldn't be grown together and of course
the why behind that. And we'll touch a little bit on
using intercropping effectively in the home garden.
We are going to bust some myths and set the record straight.
Let's dig in. Hey, I'm Karen and what started
(01:29):
as a small backyard garden 20 years ago turned into a lifelong
passion for growing food. Now as a market farmer and
horticulturist, I want to help you do the same.
On this podcast, I am your friend in the garden teaching
evidence based techniques to help you grow your favorites and
build confidence in your own garden space.
So grab your garden journal and a cup of coffee and get ready to
(01:50):
just grow something. Before we jump in, I want to
shout out my patrons over on Patreon for their continued
support of this show by either supporting my coffee habits or
just supporting the show itself with monthly support.
I wanted to shout out our newestpatron, Robin, who joined at the
(02:12):
BI Karen. A coffee level keeping me
caffeinated is a very good thingfor everybody involved.
Trust me. And I truly appreciate you Robin
and all of my other patrons who support this show monthly.
And for those of you who have did to jump on to buy me a
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(02:35):
that from patreon.com/just Grow Something or Buy Me a
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me when I get feedback from my gardening friends that tells me
that the content here is resonating with you and that you
are getting value. So thank you.
(02:56):
Thank you very, very much. So companion planting kind of
gets framed as this sort of magic bullet for pest problems,
but the reality is a little bit more nuanced than that.
And like I mentioned in the intro, there are a lot of
(03:16):
different reasons why we might want to do companion planting
and what that means for us in our garden.
So our goals with companion planting are going to dictate
what plants we actually plant totogether as companions.
True companion planting works through a couple of different
(03:38):
mechanisms. The first one would be pest
confusion. So we talked about that a little
bit last week in the pest prevention episode.
We're talking about masking scents or disrupting the pest
host location. So we talked about those
appropriate and inappropriate landings theory where a new
insect is looking for a very specific set of traits in a
(04:02):
plant to understand or to recognize that it is the place
where it's supposed to be layingits eggs.
And it will land just to kind oftest out whether or not that's
the right plant. And then it will land again.
And if it lands on a plant that isn't its host, that is
considered, it's considered an inappropriate landing, then that
kind of resets the whole processand they start all over again.
(04:24):
So this is confusing the past. It also can be done in terms of
scents. And by scent we usually mean the
chemical signals that it's giving off, which to us that
smells like something very specific, but to pests it might
smell a little bit, you know, differently than that.
But they're looking for very specific scents or chemical
(04:44):
signals for the plants that theynormally either use as a host or
predate on. And if we can use companion
planting to mask those scents and disrupt all of that, then
that is going to be successful. That is a successful companion
planting. So that's pest confusion.
The second one would be trap cropping.
So essentially this is sacrificing 1 plant to protect
(05:10):
another one. I actually discovered a really
good trap crop for kale specifically like curly kale and
other brassicas when I planted dinosaur kale for the first time
and I had it in one particular field where I was planting a lot
of my brassicas. So I had my curly kale and I had
my mustards, and I had broccoli and cauliflower and cabbage and
(05:37):
bok choy and a bunch of other greens that were all kind of in
that same sort of family. And I planted dinosaur kale for
the first time. And the dinosaur kale was torn
to shreds. And this was before I really
started relying heavily on insect netting, so most of my
stuff was not covered at this point.
(05:58):
That dinosaur kale looked like Swiss cheese.
The holes in those leaves from the cabbage moths and the
cabbage butterflies larvae as ithas.
So all those little caterpillars, the cabbage
loopers had just destroyed that dinosaur kale.
But in the process of them doingthat, the majority of my other
brassicas were being left alone and that was my first time
(06:21):
really discovering the truth behind trap cropping and it was
attracting the pests away to their preferred crop and using
that crop as a way to draw them away from the other things that
I was trying to grow. My attempt this year at trap
cropping is for my zucchini and my yellow squash.
(06:42):
So I am going back to a traditional method of of trap
cropping for zucchinis and othersquashes and that is using blue
Hubbard squash. So blue Hubbard squash is
another one that is a preferential plant for
everything that's in the squash family.
The squash buying bores and the cucumber or the the squash bugs
(07:06):
absolutely prefer the blue Hubbard squash plant for
whatever reason over the other ones that we will grow.
So the key here is to get the blue Hubbard squash to be a few
weeks more mature than the otherplants.
And so the plan is to get the blue Hubbard squash planted out
in one bed and leave it uncovered.
(07:27):
I'm also going to plant marigolds at either end, which
you'll find out why here in a minute.
And then I'm going to plant sunflowers a little bit away
from that crop. And then on the other side of
that particular field is where I'm going to plant my zucchini
and my yellow squashes and my other summer squashes, which
(07:48):
will immediately be covered withinsect netting.
And I will have nasturtiums at either end of those beds.
And then a little ways away, I'mgoing to have more sunflowers
in. Now, the idea is that the insect
pests are going to be more attracted to the blue Hubbard
squash #1 because it's going to be a little bit more mature and
#2 because it is the preferred crop #3 it will not be covered.
(08:12):
And so it'll be an easier targetfor those pests.
In addition to that, the sunflowers hopefully are going
to attract birds to feed on the sunflowers, which also are going
to feed on the insect pests thatare in the blue Hubbard squash,
which will be very close by. And the idea here is that all of
(08:33):
those pests will go over to the blue Hubbard.
And so when it's time to uncoverthe yellow squashes and the
zucchini on this side, because obviously they have to be
uncovered in order to be pollinated, then it'll be less
likely to attract those pests tothe other side.
I'm not thinking that this is going to completely, 100%
protect my zucchini in my yellowsquash, but it's hopefully going
(08:54):
to draw away the majority of those insect pests and get them
over to the blue Hubbard. Now with trap cropping it, it
may not necessarily be just about drawing them away.
You might use it literally as a trap.
You're trapping these pests by in some way eliminating them
once they are in that crop. So this might be pulling that
(09:14):
crop completely and getting rid of it and the pests along with
it. This might be spraying something
like an, you know, insecticidal soap or something to knock that
insect pest population down so that they can't go over and
predate on your other ones. There's all kinds of ways to do
this, but that's the essential idea behind trap cropping.
Another way that we can effect companion planting is through
(09:38):
allelopathy. And allelopathy is basically a
plant that exudes chemical signals oftentimes either
through their roots or through their plant tissue that inhibit
some other growth or that do something with those chemicals.
So for example, with marigolds, we're talking about them
(10:00):
exudating a a root exit called thiopine that has been shown to
suppress root, not nematodes, right?
For sunflowers, this is going tobe them keeping weeds at Bay.
So we'll talk about that a little bit more in depth.
But that is another way that we were, we would use companion
planting as a way to help prevent things or accomplish
(10:23):
things in the garden. And then we also can use
companion plants for attracting beneficial insects.
So this might be more of an ideaof we're going to plant these
things in order to bring in natural predators or to bring in
more pollinators in order to help us combat some of the other
things that are going on in our garden.
(10:45):
You could also look at some of the inter planting that we do
and use and consider that some companion planting, especially
when in terms of maybe we're having some of the plants act as
a living mulch. So think about the three sisters
method, OK, if you're not familiar with the three sisters,
essentially it is a traditional way of growing three specific
(11:06):
crops. You're growing corn generally.
We're not talking about sweet corn here.
We're talking about dent corn orflour type corns.
So this is a dried corn, which means those stocks are going to
be out there for an extended period of time.
But at the same time you are planting beans, whole beans, at
the base of those corn plants sothe beans can climb up the corn.
(11:27):
And then you are planting pumpkins or some other type of a
winter squash in and amongst thecorn and it is crawling across
the ground and it is suppressingweeds.
So in this instance, this is a companion planting technique
that has nothing to do with keeping predatory insects out.
This is all about one plant supporting the other, supporting
(11:48):
the other, right? The the corn is acting as a
trellis for the beans. The beans are fixing nitrogen
into the soil that the corn really needs for its growth.
And then the squashes are viningin and amongst all of those
plants and they are providing ground cover which is helping to
keep the weeds at Bay. So not all companion planting is
(12:09):
specific to insect pests. It can be, but we just just want
to understand what mechanism we are interested in when we are
deciding what to plant with eachone of our crops.
OK, so that's the first thing. But a lot of companion planting
charts are aimed at, you know, insect pests, and a lot of them
(12:35):
really rely very heavily just onanecdote.
And there isn't really any scientific backing to them.
This is not to say that it's nottrue, OK?
We've talked before about, you know, there's a difference
between causation and correlation.
And you know, us planting, you know, our basil with our
tomatoes and it's seeming like it the tomatoes tasted better
(12:57):
that year doesn't necessarily mean that's actually what
happened because there are so many other factors that could be
going on in our yards. This also doesn't mean that even
if it is backed by science, thatit is necessarily going to work
for you in your garden because your soil type, your climate,
your amount of rainfall, all of those things are going to affect
(13:22):
how plants perform. And you know what type of
chemical signals or how strong the chemical signals are that
they give off. It's a lot of scientific based
information is based in a laboratory setting where things
are very well controlled. And as you have probably
experienced as a gardener, nothing is well controlled in
(13:42):
our gardens. Even when you find science
backed information, always thinkthat you know, you should be
taking that with a little bit ofa grain of salt and
understanding that it it may notwork as well for you in your
garden as it did in the researchgarden or the research plot.
OK, so let's look at some popular companion plants and
what the research actually says or doesn't say about them.
(14:05):
And the very first one that we're going to talk about is
marigolds, because this is stillprobably one of the most
misunderstood companion plants in the home garden.
So this week I noticed my rose Bush from heirloom roses was
putting on a lot of beautiful green leafy growth.
And then I wondered if there wasanything specific that I needed
(14:28):
to do with the plant in terms ofspring care or more
specifically, pruning. I have mentioned I am not
someone who has had very good experiences with roses in the
past, and I honestly have no idea when it's a good time to
perform certain tasks just to make sure that it's living its
best little rose life. thankfullyheirloomroses.com has
(14:51):
a ton of resources to make my life easier and help me make the
best decisions for when and how to care for my rose, not just
now in its first full year in its pot out front, but for years
to come. They also provide emails every
week that give me more tips and tricks for keeping my rose
(15:11):
healthy, answering questions I didn't even think to ask.
This just makes me even more confident to go find maybe
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(15:35):
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The link is in the show notes. I was one of those people who
(15:56):
recommended and used to plant marigolds with literally
everything in my garden. I planted them in and amongst
all of my zucchinis. I put them in and amongst all of
my cabbages and my brassicas. I put them in my tomatoes like I
used them everywhere. And let's be very clear, we're
talking specifically about French marigolds here.
(16:16):
So this is to Jetty's Pitula. You can also use Mexican
marigolds. They're a little bit different
the, the other one, not the friend.
The African marigolds do not work nearly as well in terms of
companion planting. You want the ones that really do
give off a very strong scent, that very particular scent.
The the African marigolds are very pretty, but they're not
(16:37):
really good in terms of companion planting for, for
specifically for insect pests. They might be, you know, good at
attracting pollinators and such,but not so much for insect
pests. OK, Like I mentioned with the
French marigolds, they do give off root exudates called
thiapine, and those have been shown to suppress nematodes.
(16:59):
OK. But when we're talking, and so
if you have nematodes and you have specifically root, not
nematodes in your tomatoes or other crops, then yeah,
absolutely you can use marigoldsin terms of above ground crops
or above ground pests. I mean marigolds do not repel
all pests. As a matter of fact, they
(17:19):
actually are attractive to certain pests.
So this is where you have to decide what pest is it that you
want to repel if you are interplanting them amongst your
crops or what pests are you wanting to attract if you are
using it as a trap crop to draw pests away from your crop.
(17:41):
OK, so if you have problems withaphids, whiteflies, melon worms
and pickle worms, coddling moths.
So these are the moths that plague like your apple fruits
and your other palm fruits, those root nut nematodes,
diamondback moths or cabbage stem flea beetles, then yes,
(18:03):
marigolds are good at repelling those things.
OK, so this is something where if you have cabbage stem flea
beetles or you are dealing with aphids or whiteflies and you can
interplant marigolds in and amongst those crops that you are
trying to protect from those specific pests.
(18:24):
But if your pest problem involves squash bugs or squash
vine boars or cucumber beetles, you guys know those are my top
three, right? Leaf hoppers, spider mites,
tarnish plant bug, beet armyworm, cabbage loopers,
tobacco budworms, flea beetles, other than the cabbage stem flea
(18:46):
beetles. So the striped flea beetles or
the western black, all the otherones, right?
Or thrips. Then you need to be aware that
marigolds are actually attractive to those insects.
So now you know why I would be planting marigolds in with my
blue Hubbard squash. Because I want the squash bugs
(19:08):
and the squash vine boars to go over into those blue Hubbard
squashes. I want them away from my other
ones. The one thing that I failed to
mention too, is that the other thing that I'm putting over in
those blue Hubbard squash plantsis some pheromone traps for the
squash vine bore. So I really want everything, all
(19:28):
those insects to go over to thatcrop over there.
And so I'm going to use the marigolds for that.
Now, in terms of like my brassicas where I used to always
plant marigolds in and amongst my cabbages and my broccoli and
my cauliflower, that was a really bad idea because my
problem is not with cabbage stemflea beetle, which is repelled
(19:51):
by the marigolds. My problem is with cabbage
loopers and marigolds attract cabbage loopers.
So that was not a really good idea for me.
I should be planting the marigolds away from my cabbage
and other brassica brassica crops.
So now what I do is when I plantmy brassicas, I am planting
alyssum and I'm planting onions and I am planting lettuces and
(20:14):
intermixing all of that together.
And then I am covering it with that insect netting.
And then I am planting marigoldsfurther away from those beds so
that I'm trying to draw those cabbage loopers away, right?
You need to plant according to your goal.
And marigolds are also attractive to the beneficials to
(20:35):
some of the beneficial, so like ladybugs and hoverflies and some
of the parasitoids and predatoryinsects.
So just plant according to your goal.
What is it that you are trying to achieve and use marigolds in
that instance? So what about like planting
basil with tomatoes? There actually is no strong
(20:56):
scientific evidence that basil does anything in terms of like
repelling tomato hornworms. As to what is often touted for
doing or improving the flavor ofthe tomato, there is anecdotal
data that suggests it might helprepel thrips, and that maybe the
strong scent of the basil can help repel other insects.
(21:19):
And basil does attract pollinators.
This can actually be true of a lot of different strong scented
herbs and flowers, so this may not be specific to basil with
tomatoes. It doesn't mean again, that
these things aren't true, it just means that there isn't any
actual evidence. So there is no harm in planting
(21:40):
them together, but you just shouldn't rely on basil alone
for your pest control. So in addition to planting basil
in with my tomatoes, which I absolutely do, I absolutely do
this. I do think they go well together
and I will actually plant multiple varieties of basils.
So the green like Italian basils, sweet basils that we
(22:01):
harvest to, to sell in bunches of actual basil leaves.
I also plant different types of basil that maybe I'm not
harvesting to sell, but I'm allowing them to go to flower
because they do put off such beautiful flowers and a lot of
pollinators and other insects are attracted to that.
And of course that helps the tomatoes.
But also I am planting things like, you know, marigolds down
(22:23):
at the ends or in and amongst the the tomatoes.
And I am going to plant sunflowers down at the end of
that section of the garden to attract the birds.
And the birds are trying to pickoff the things like the tomato
hornworms that might actually bedamaging my tomatoes, but that
maybe the basil isn't repelling.I am not relying on just one
(22:44):
planting or one companion to do these jobs.
I am, you know, loading my basesand making sure that every
single thing that's out there has some sort of different
mechanism for helping me with these insect pests.
So no harm in planting them together, but don't rely on
basil alone for your pest control.
(23:04):
Another one would be porridge and planting that near squash or
tomatoes. Porridge flowers do attract
pollinators and they attract beneficial Wasps and some of
those beneficial Wasps are the ones that will predate on those
tomato hornworms. You may have seen images of
tomato hornworms with eggs laid on them.
(23:26):
It's fascinating to see. And what that is, is these
predatory Wasps have come in andhave laid their eggs on the
hornworms. And when those eggs hatch, then
they essentially eat the hornworms.
And so you're kind of disruptingthat hornworm reproduction cycle
right there. So, and there have been some
studies that do show if you weretomato hornworms on plants that
are planted near borage, You just have to remember that
(23:48):
borage grows very large, so you want to space it appropriately
to avoid shading anything nearby.
So it's fine to do them with thetomatoes because they're both
fairly tall. But if you're doing it near
squash, you want to do this likesort of appropriately, right?
I keep mentioning sunflowers andI use sunflowers to attract
birds that will predate on the insects in my garden.
(24:12):
And thereby I am helping to reduce the pests.
But I do shy away from planting anything too close to the base
of those plants because sunflower can be a highly
allelopathic plant. It's phytotoxic potential has
been shown on crops and weeds innot just laboratory settings,
(24:35):
but also in greenhouse and fieldtrials.
And they've done all kinds of tests on this with different,
you know, a variety of factors like the concentration of how
many sunflowers are growing and the different species and the
different genotypes. So, you know, again, sunflower
are another one that kind of gives off these, these root
exudates that are chemicals thatare going to inhibit the growth
(24:59):
of other plants in and around the base of the sunflowers.
Which means that sunflowers are a good crop to plant for
suppressing weeds, especially annual weeds, because it's going
to prevent them from coming up. But it may not be something that
you want to plant within a few feet of any crop that you
actually intend to harvest. Which it's kind of a shame
because, you know, we talked about the Three Sisters method.
(25:21):
And if you think about a sunflower, they have such real
good sturdy stalks. You would hope that it would be
something that you would be ableto use as like a natural trellis
like the corn in the three Sisters method.
But unfortunately, most crops are not going to be able to
handle the chemical signals or the chemicals that are being
released from those roots. And if they are something that
(25:44):
could handle those allelopathic properties, the other way a
plant could be allelopathic, meaning it is preventing the
growth of things near it is to be basically a nutrient hog.
Sunflower is a very demanding plant and it can usually out
compete anything that it is planted with.
So sunflowers have very deep taproots.
(26:08):
I did a whole episode on sunflowers and their ability to
be able to. I guess it wasn't a whole
episode specific to sunflowers, but it was talking about phyto
remediation, which is the ability to be able to draw
toxins and other contaminants out of the soil.
Sunflowers are fantastic for that and if they have that
ability then you know they have a very, very strong root system.
(26:31):
So they are going to out competejust about anything.
The only thing that I have really seen them not be able to
handle at least in my area is a heavy growth of hemlock plant.
Like we have hemlock out here that is just invasive and goes
crazy. And I had tried planting
sunflowers to kind of out compete the hemlock and the
(26:52):
hemlock just it takes over everytime.
So that's something that we havedealt with.
But sunflower great for suppressing weeds, especially
annual weeds, but you you may not want to plant any actual
harvestable crops anywhere near the base of them.
Now, sometimes a plant that we plant intending for it to help
can actually do the opposite. I'm all about experimenting with
(27:17):
companion plants to see what works and what doesn't work in
your garden in your experience. Again, we don't always have to
rely on these science research studies, et cetera, to show us
what works in our own garden. I just don't like to spread that
information to people once I seesomething works for me because
it may not work for somebody else if I just have anecdotal
(27:39):
information, right? But there are, you know, certain
cases where we know something doesn't work for very specific
reasons. For example, dill.
Dill attracts swallowtail caterpillars, which you know
actually it attacks this that tracks the butterfly and they
like to lay their eggs in the dill.
This also is in parsley as well,but dill specifically, and dill
(28:03):
also attracts aphids so you probably don't want to be
planting those near your tomatoes because you're
encouraging those caterpillars and you're encouraging aphids to
be in your tomatoes. Mature dill can also suppress
tomato growth first via that allelopathy early on.
So you know the early plants aren't so bad, but once they
(28:23):
start to go to flour then the dill can cause a problem.
So it's not usually a good idea to plant dill near your
tomatoes. Same thing goes with sunflowers.
Again, anywhere near beans. So, you know, I will plant
sunflowers along end rows in my garden.
It's usually the one thing that I don't plant in amongst
(28:44):
everything else. But if I'm going to plant beans,
they're going to be at the opposite end of that garden area
because sunflowers can actually attract stink bugs and they can
harbor seed maggots. And this is not something that
we want in our beans because beans are very susceptible to
the damage from those. They're great for pollinators,
the sunflowers are, but you justwant to make sure that you're
monitoring them closely near anyof those vulnerable crops.
(29:06):
Another one is fennel. Fennel also has allelopathic
compounds and it can inhibit thegrowth of a lot of vegetables,
most of them actually. So if you are growing fennel,
you likely want to plant it by itself.
And it's a great plant that you can put in a separate pollinator
bed and because it does again, attracts those things like
(29:28):
swallowtail butterflies. And so if you are growing fennel
as your crop to eat, then you want to keep it away from the
rest of your crops that it doesn't actually inhibit the
growth of the rest of your garden.
OK, so there are a few more plants that we may not want to
plant together just you know based on olelapathy or even just
(29:50):
direct competition. The first one is planting onions
or garlic in an amongst beans. So one of the things that we
get, one of the benefits that weget from planting beans or
anything else in the Allium or in the legume family, sorry, in
the legume family, is that beansand other legumes add nitrogen
(30:10):
to the soil through a symbiotic relationship with rhizobium
bacteria. These these bacteria form
nodules on the bean roots, so they convert atmospheric
nitrogen into a form that the plant can use through those
nodules. When the plant dies or when we
(30:31):
cut it down, we leave that root system in the ground, which
means those nodules are still inthe soil.
And then as they decompose, theyrelease that fixed nitrogen back
out into the soil. And that of course, helps enrich
the soil for future crops. If we plant onions or garlic,
any of our alliums next to our beans or near our legumes, it's
(30:55):
a bad idea because alliums release sulfur compounds and
Allison, which is an antibacterial compound.
And those compounds can actuallykill off the beneficial nitrogen
fixing bacteria that are doing that job for us.
That's those are the bacteria that the legumes need for that
(31:15):
nitrogen fixing. So not only is that going to
affect the plants ability, the bean plants ability to be able
to kind of store up that nitrogen for us and give us
those benefits, but it actually may interfere with the bean
plants growth itself. So we want to avoid planting
onions or garlic in and around near our beans.
Another one would be carrots anddill or parsnip.
(31:38):
These are all in the APACA family and so they can cross
attract carrot flies and also attract the same diseases.
So we don't want to group them together.
The same thing goes basically for other plant families.
So nasturtiums, for example, nasturtiums will repel a lot of
different pests, but nasturtiumsare in the brassica family.
(32:00):
And so it would be probably a bad idea to plant nasturtiums in
and amongst all of your brassicas because they're not
going to be very effective at the pests that we're worried
about in our brassicas, like thecabbage moths or other pests,
because the phytochemicals are all the same.
So This is why we generally don't want to plant things in
the same family all together. Same thing goes with like
(32:22):
potatoes and tomatoes. They're both in the nightshade
family, so they are both susceptible to the same fungal
and bacterial diseases, especially blight.
So we want to separate them to reduce that risk.
Does this mean that I'm not planting my brassicas all like
near each other? No, I'm still planting them in
beds that are close to each other because again, we talk
(32:44):
about this all the time. We're not farming on 1000 acres
here, right? And I mean, even I have more
room to plant than a lot of other people do.
But if you're gardening in your backyard, you only have a
limited amount of space. So you're obviously going to
have to be planting some of these plants close to each
other, right? So it's just important to,
again, use that companion planting to mix up all the
(33:05):
species. Tomatoes and corn, these are
both really heavy feeders and they're going to compete for
nutrients a lot of time. Plus corn can host the the corn
earworm, which is also known as a tomato fruit worm.
So that also targets tomatoes. We don't want those pests coming
in and landing on one and also being able to feed on the other.
(33:27):
So those can be, you know, both of the plants weak and it opens
them up to different pests and diseases.
So we don't want to plant those together either In terms of
companion planting with strategy, right?
This is where intercropping or interplanting comes into play.
We're going to talk next week about the strategies like really
dive deep into the kind of systematic version or way that
(33:52):
we can companion plant through intercropping.
It's based on timing, it's basedon spacing, it's based on plant
architecture, all of these different things.
But some of the ones, you know, just here briefly that we can
touch on that are really good examples are things like what we
already talked about the three sisters, right, corn, beans and
squash. The beans fix the nitrogen the
corn provides support the squashsuppresses the weeds.
(34:15):
And you can also deter like raccoons and stuff from getting
into your corn because the if you're using the squashes that
have like the spiky stems on them, that can actually help,
you know, keep those buggers from crawling in there and
trying to climb up the corn and and pull the corn down.
So lots of different benefits toeach other when they're being
planted together, planting fast growing crops with slow growing
(34:39):
ones. So radishes or lettuce being
planted in between longer maturing crops like the broccoli
or your Peppers, not only is maximizing space, it's also
reducing that weed pressure. So those are good companions
together. But again, when we're talking
about deterring pests, we're mixing up those chemical signals
by planting multiple plant families together.
(35:01):
So that is deterring the pests because they can't find their
preferred host nearly as easily,especially, again, appropriate,
inappropriate landings. They land on a radish and go,
oop, that's not what I wanted. I want to land on the carrot and
then they might land on the carrot and then they land again
and oops, back on a radish again.
Like it's it it resets that whole cycle.
So the more things that we can plant together that are not in
(35:22):
the same plant family, the better off we are.
This kind of inter planting, youknow, rows of of non host crops
not only visually confuses the pest, but it also, you know, can
confuse them in terms of like the texture and the landing on
them, right? So alternating rows of onions
and carrots that can mask each of those crops from their
(35:43):
respective pests like onion maggots and the carrot rust
flies, et cetera. This is why when I'm planting my
brassicas again, they are being planted near each other.
I might have one full bed that has all, you know, broccoli in
it. That bed right next to it may
also have cabbage in it. And then the one right next to
that might have cauliflower in it.
But they're not by themselves. They are not growing by
(36:06):
themselves ever in those beds. So even though those all attract
the same pests, I am inter planting those onions and those
lettuces and the the Elysium in and amongst them.
So it is still confusing those pests, right?
That is how you kind of get around the space issue when it
(36:26):
comes to growing your crops. If you can inter plant them and
confuse those pests, that's going to help.
To be most effective, we want tochoose crops that have different
growth rates and that also have different canopy shapes and we
don't want to overcrowd. This is probably the most
difficult part of this and something we're going to kind of
deep dive into next week. Intercropping works best when
(36:49):
you have a plan and you understand the mature size of
these plants and how they're going to affect each other when
they are all at maturity, whether or not they've already
been pulled or not and that sortof thing.
So we'll go into that a little bit more next week.
Companion planting absolutely works, right, whether or not
(37:15):
we're using it in terms of, you know, increasing our soil health
or protecting our, our, our soilor keeping weeds at Bay or in
terms of pest management. But it works best as part of an
integrated pest management strategy.
I will link to the IPM episode that I did earlier in the
(37:36):
season. But this means prioritizing
plant health and soil health, right?
Because again, our healthy plants and our healthy soil are
going to be much better at resisting those pests and being
able to bounce back once they are predated on and on
monitoring for that pest presence and keeping track of
those lifestyles, life cycles sothat we know when and how those
(37:59):
pests are operating. And then combining all of this
companion planting with using physical barriers and natural
predators when appropriate. Doing your homework on which
companions actually have evidence behind them is a really
good place to start. And is also going to sort of
(38:19):
weed out which ones might just be garden folklore.
A lot of plants do express insecticidal traits.
The key is to use them for your benefit and use them on plants
that are very dissimilar and that way they produce different
phytochemicals. So again that you know that
(38:40):
reference to the nasturtiums, they do repel pests, but they
are in the Brassica family. So maybe don't use them to try
to deter pests from others in that family.
Put them in with something else like maybe your squash plants.
And if you have, you know, or, or just use them as a trap crop,
if you have tried a companion planting combo that works for
(39:01):
you, there is no reason not to continue it if you know it's
working. And you can go ahead and share
that, you know, let me know. I would love to, you know, hear
some real world examples of things that have worked for you.
If you have tried a companion planting that totally flopped
and maybe you didn't realize whyit flopped until later on or
(39:22):
even just now listening to this episode and realizing, oh,
nasturtiums attract aphids and Iwas trying to get rid of aphids
but I put them in and they were,oh, now I understand.
Go ahead and let me know that too.
I would love to hear about it again.
If I hear a bunch of real world examples from people, I am super
happy to, you know, update everybody in a future episode to
(39:42):
let them know like, hey, this has worked for some people,
maybe it'll work for you. Just remember, when you are
dealing with anecdotal companionplantings, what works for one
person may not work for another one.
So do not rely on any of these companion planting suggestions
as your sole way to keep insect pests at Bay in your garden.
(40:04):
Make sure it's part of an integrated plan and that you
have more than one way to keep away those pests.
Until next time, my gardening friends, keep on cultivating
that dream garden and we'll talkwith you soon.
If you have been gardening for any amount of time, you have
likely come across companion planting charts.
Maybe you have seen advice that says plant basil with tomatoes,
or just general advice to plant marigolds with everything
because they repel pests. But how much of this is actually
true? Companion planting can mean a
(00:20):
lot of things. Depending on what our goal is.
We can either be going for pest repelling properties, or we
could be aiming to keep weeds down.
We might be looking for soil health benefits or just
enhancing flavors or saving space.
Today I'll just grow something. We are sorting fact from
fiction. Some companion planting
practices do have solid evidencebehind them, or I should say
(00:44):
solid science. But a lot of claims are more
anecdotal than evidence based. And in some cases we might be
doing some well intended pairings that may even backfire.
I'm looking at you marigolds. So we will talk about what the
research says about using specific plants to either deter
or attract pests, when companionplanting works and when it
(01:08):
doesn't, which plants shouldn't be grown together and of course
the why behind that. And we'll touch a little bit on
using intercropping effectively in the home garden.
We are going to bust some myths and set the record straight.
Let's dig in. Hey, I'm Karen and what started
(01:29):
as a small backyard garden 20 years ago turned into a lifelong
passion for growing food. Now as a market farmer and
horticulturist, I want to help you do the same.
On this podcast, I am your friend in the garden teaching
evidence based techniques to help you grow your favorites and
build confidence in your own garden space.
So grab your garden journal and a cup of coffee and get ready to
(01:50):
just grow something. Before we jump in, I want to
shout out my patrons over on Patreon for their continued
support of this show by either supporting my coffee habits or
just supporting the show itself with monthly support.
I wanted to shout out our newestpatron, Robin, who joined at the
(02:12):
BI Karen. A coffee level keeping me
caffeinated is a very good thingfor everybody involved.
Trust me. And I truly appreciate you Robin
and all of my other patrons who support this show monthly.
And for those of you who have did to jump on to buy me a
coffee and send over a one time support in terms of a coffee or
three, if you are interested in supporting the show, you can do
(02:35):
that from patreon.com/just Grow Something or Buy Me a
coffee.com/just Grow Something. I will link to both of those in
the show notes. It absolutely means the world to
me when I get feedback from my gardening friends that tells me
that the content here is resonating with you and that you
are getting value. So thank you.
(02:56):
Thank you very, very much. So companion planting kind of
gets framed as this sort of magic bullet for pest problems,
but the reality is a little bit more nuanced than that.
And like I mentioned in the intro, there are a lot of
(03:16):
different reasons why we might want to do companion planting
and what that means for us in our garden.
So our goals with companion planting are going to dictate
what plants we actually plant totogether as companions.
True companion planting works through a couple of different
(03:38):
mechanisms. The first one would be pest
confusion. So we talked about that a little
bit last week in the pest prevention episode.
We're talking about masking scents or disrupting the pest
host location. So we talked about those
appropriate and inappropriate landings theory where a new
insect is looking for a very specific set of traits in a
(04:02):
plant to understand or to recognize that it is the place
where it's supposed to be layingits eggs.
And it will land just to kind oftest out whether or not that's
the right plant. And then it will land again.
And if it lands on a plant that isn't its host, that is
considered, it's considered an inappropriate landing, then that
kind of resets the whole processand they start all over again.
(04:24):
So this is confusing the past. It also can be done in terms of
scents. And by scent we usually mean the
chemical signals that it's giving off, which to us that
smells like something very specific, but to pests it might
smell a little bit, you know, differently than that.
But they're looking for very specific scents or chemical
(04:44):
signals for the plants that theynormally either use as a host or
predate on. And if we can use companion
planting to mask those scents and disrupt all of that, then
that is going to be successful. That is a successful companion
planting. So that's pest confusion.
The second one would be trap cropping.
So essentially this is sacrificing 1 plant to protect
(05:10):
another one. I actually discovered a really
good trap crop for kale specifically like curly kale and
other brassicas when I planted dinosaur kale for the first time
and I had it in one particular field where I was planting a lot
of my brassicas. So I had my curly kale and I had
my mustards, and I had broccoli and cauliflower and cabbage and
(05:37):
bok choy and a bunch of other greens that were all kind of in
that same sort of family. And I planted dinosaur kale for
the first time. And the dinosaur kale was torn
to shreds. And this was before I really
started relying heavily on insect netting, so most of my
stuff was not covered at this point.
(05:58):
That dinosaur kale looked like Swiss cheese.
The holes in those leaves from the cabbage moths and the
cabbage butterflies larvae as ithas.
So all those little caterpillars, the cabbage
loopers had just destroyed that dinosaur kale.
But in the process of them doingthat, the majority of my other
brassicas were being left alone and that was my first time
(06:21):
really discovering the truth behind trap cropping and it was
attracting the pests away to their preferred crop and using
that crop as a way to draw them away from the other things that
I was trying to grow. My attempt this year at trap
cropping is for my zucchini and my yellow squash.
(06:42):
So I am going back to a traditional method of of trap
cropping for zucchinis and othersquashes and that is using blue
Hubbard squash. So blue Hubbard squash is
another one that is a preferential plant for
everything that's in the squash family.
The squash buying bores and the cucumber or the the squash bugs
(07:06):
absolutely prefer the blue Hubbard squash plant for
whatever reason over the other ones that we will grow.
So the key here is to get the blue Hubbard squash to be a few
weeks more mature than the otherplants.
And so the plan is to get the blue Hubbard squash planted out
in one bed and leave it uncovered.
(07:27):
I'm also going to plant marigolds at either end, which
you'll find out why here in a minute.
And then I'm going to plant sunflowers a little bit away
from that crop. And then on the other side of
that particular field is where I'm going to plant my zucchini
and my yellow squashes and my other summer squashes, which
(07:48):
will immediately be covered withinsect netting.
And I will have nasturtiums at either end of those beds.
And then a little ways away, I'mgoing to have more sunflowers
in. Now, the idea is that the insect
pests are going to be more attracted to the blue Hubbard
squash #1 because it's going to be a little bit more mature and
#2 because it is the preferred crop #3 it will not be covered.
(08:12):
And so it'll be an easier targetfor those pests.
In addition to that, the sunflowers hopefully are going
to attract birds to feed on the sunflowers, which also are going
to feed on the insect pests thatare in the blue Hubbard squash,
which will be very close by. And the idea here is that all of
(08:33):
those pests will go over to the blue Hubbard.
And so when it's time to uncoverthe yellow squashes and the
zucchini on this side, because obviously they have to be
uncovered in order to be pollinated, then it'll be less
likely to attract those pests tothe other side.
I'm not thinking that this is going to completely, 100%
protect my zucchini in my yellowsquash, but it's hopefully going
(08:54):
to draw away the majority of those insect pests and get them
over to the blue Hubbard. Now with trap cropping it, it
may not necessarily be just about drawing them away.
You might use it literally as a trap.
You're trapping these pests by in some way eliminating them
once they are in that crop. So this might be pulling that
(09:14):
crop completely and getting rid of it and the pests along with
it. This might be spraying something
like an, you know, insecticidal soap or something to knock that
insect pest population down so that they can't go over and
predate on your other ones. There's all kinds of ways to do
this, but that's the essential idea behind trap cropping.
Another way that we can effect companion planting is through
(09:38):
allelopathy. And allelopathy is basically a
plant that exudes chemical signals oftentimes either
through their roots or through their plant tissue that inhibit
some other growth or that do something with those chemicals.
So for example, with marigolds, we're talking about them
(10:00):
exudating a a root exit called thiopine that has been shown to
suppress root, not nematodes, right?
For sunflowers, this is going tobe them keeping weeds at Bay.
So we'll talk about that a little bit more in depth.
But that is another way that we were, we would use companion
planting as a way to help prevent things or accomplish
(10:23):
things in the garden. And then we also can use
companion plants for attracting beneficial insects.
So this might be more of an ideaof we're going to plant these
things in order to bring in natural predators or to bring in
more pollinators in order to help us combat some of the other
things that are going on in our garden.
(10:45):
You could also look at some of the inter planting that we do
and use and consider that some companion planting, especially
when in terms of maybe we're having some of the plants act as
a living mulch. So think about the three sisters
method, OK, if you're not familiar with the three sisters,
essentially it is a traditional way of growing three specific
(11:06):
crops. You're growing corn generally.
We're not talking about sweet corn here.
We're talking about dent corn orflour type corns.
So this is a dried corn, which means those stocks are going to
be out there for an extended period of time.
But at the same time you are planting beans, whole beans, at
the base of those corn plants sothe beans can climb up the corn.
(11:27):
And then you are planting pumpkins or some other type of a
winter squash in and amongst thecorn and it is crawling across
the ground and it is suppressingweeds.
So in this instance, this is a companion planting technique
that has nothing to do with keeping predatory insects out.
This is all about one plant supporting the other, supporting
(11:48):
the other, right? The the corn is acting as a
trellis for the beans. The beans are fixing nitrogen
into the soil that the corn really needs for its growth.
And then the squashes are viningin and amongst all of those
plants and they are providing ground cover which is helping to
keep the weeds at Bay. So not all companion planting is
(12:09):
specific to insect pests. It can be, but we just just want
to understand what mechanism we are interested in when we are
deciding what to plant with eachone of our crops.
OK, so that's the first thing. But a lot of companion planting
charts are aimed at, you know, insect pests, and a lot of them
(12:35):
really rely very heavily just onanecdote.
And there isn't really any scientific backing to them.
This is not to say that it's nottrue, OK?
We've talked before about, you know, there's a difference
between causation and correlation.
And you know, us planting, you know, our basil with our
tomatoes and it's seeming like it the tomatoes tasted better
(12:57):
that year doesn't necessarily mean that's actually what
happened because there are so many other factors that could be
going on in our yards. This also doesn't mean that even
if it is backed by science, thatit is necessarily going to work
for you in your garden because your soil type, your climate,
your amount of rainfall, all of those things are going to affect
(13:22):
how plants perform. And you know what type of
chemical signals or how strong the chemical signals are that
they give off. It's a lot of scientific based
information is based in a laboratory setting where things
are very well controlled. And as you have probably
experienced as a gardener, nothing is well controlled in
(13:42):
our gardens. Even when you find science
backed information, always thinkthat you know, you should be
taking that with a little bit ofa grain of salt and
understanding that it it may notwork as well for you in your
garden as it did in the researchgarden or the research plot.
OK, so let's look at some popular companion plants and
what the research actually says or doesn't say about them.
(14:05):
And the very first one that we're going to talk about is
marigolds, because this is stillprobably one of the most
misunderstood companion plants in the home garden.
So this week I noticed my rose Bush from heirloom roses was
putting on a lot of beautiful green leafy growth.
And then I wondered if there wasanything specific that I needed
(14:28):
to do with the plant in terms ofspring care or more
specifically, pruning. I have mentioned I am not
someone who has had very good experiences with roses in the
past, and I honestly have no idea when it's a good time to
perform certain tasks just to make sure that it's living its
best little rose life. thankfullyheirloomroses.com has
(14:51):
a ton of resources to make my life easier and help me make the
best decisions for when and how to care for my rose, not just
now in its first full year in its pot out front, but for years
to come. They also provide emails every
week that give me more tips and tricks for keeping my rose
(15:11):
healthy, answering questions I didn't even think to ask.
This just makes me even more confident to go find maybe
another new rose to add upfront this year.
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(15:35):
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The link is in the show notes. I was one of those people who
(15:56):
recommended and used to plant marigolds with literally
everything in my garden. I planted them in and amongst
all of my zucchinis. I put them in and amongst all of
my cabbages and my brassicas. I put them in my tomatoes like I
used them everywhere. And let's be very clear, we're
talking specifically about French marigolds here.
(16:16):
So this is to Jetty's Pitula. You can also use Mexican
marigolds. They're a little bit different
the, the other one, not the friend.
The African marigolds do not work nearly as well in terms of
companion planting. You want the ones that really do
give off a very strong scent, that very particular scent.
The the African marigolds are very pretty, but they're not
(16:37):
really good in terms of companion planting for, for
specifically for insect pests. They might be, you know, good at
attracting pollinators and such,but not so much for insect
pests. OK, Like I mentioned with the
French marigolds, they do give off root exudates called
thiapine, and those have been shown to suppress nematodes.
(16:59):
OK. But when we're talking, and so
if you have nematodes and you have specifically root, not
nematodes in your tomatoes or other crops, then yeah,
absolutely you can use marigoldsin terms of above ground crops
or above ground pests. I mean marigolds do not repel
all pests. As a matter of fact, they
(17:19):
actually are attractive to certain pests.
So this is where you have to decide what pest is it that you
want to repel if you are interplanting them amongst your
crops or what pests are you wanting to attract if you are
using it as a trap crop to draw pests away from your crop.
(17:41):
OK, so if you have problems withaphids, whiteflies, melon worms
and pickle worms, coddling moths.
So these are the moths that plague like your apple fruits
and your other palm fruits, those root nut nematodes,
diamondback moths or cabbage stem flea beetles, then yes,
(18:03):
marigolds are good at repelling those things.
OK, so this is something where if you have cabbage stem flea
beetles or you are dealing with aphids or whiteflies and you can
interplant marigolds in and amongst those crops that you are
trying to protect from those specific pests.
(18:24):
But if your pest problem involves squash bugs or squash
vine boars or cucumber beetles, you guys know those are my top
three, right? Leaf hoppers, spider mites,
tarnish plant bug, beet armyworm, cabbage loopers,
tobacco budworms, flea beetles, other than the cabbage stem flea
(18:46):
beetles. So the striped flea beetles or
the western black, all the otherones, right?
Or thrips. Then you need to be aware that
marigolds are actually attractive to those insects.
So now you know why I would be planting marigolds in with my
blue Hubbard squash. Because I want the squash bugs
(19:08):
and the squash vine boars to go over into those blue Hubbard
squashes. I want them away from my other
ones. The one thing that I failed to
mention too, is that the other thing that I'm putting over in
those blue Hubbard squash plantsis some pheromone traps for the
squash vine bore. So I really want everything, all
(19:28):
those insects to go over to thatcrop over there.
And so I'm going to use the marigolds for that.
Now, in terms of like my brassicas where I used to always
plant marigolds in and amongst my cabbages and my broccoli and
my cauliflower, that was a really bad idea because my
problem is not with cabbage stemflea beetle, which is repelled
(19:51):
by the marigolds. My problem is with cabbage
loopers and marigolds attract cabbage loopers.
So that was not a really good idea for me.
I should be planting the marigolds away from my cabbage
and other brassica brassica crops.
So now what I do is when I plantmy brassicas, I am planting
alyssum and I'm planting onions and I am planting lettuces and
(20:14):
intermixing all of that together.
And then I am covering it with that insect netting.
And then I am planting marigoldsfurther away from those beds so
that I'm trying to draw those cabbage loopers away, right?
You need to plant according to your goal.
And marigolds are also attractive to the beneficials to
(20:35):
some of the beneficial, so like ladybugs and hoverflies and some
of the parasitoids and predatoryinsects.
So just plant according to your goal.
What is it that you are trying to achieve and use marigolds in
that instance? So what about like planting
basil with tomatoes? There actually is no strong
(20:56):
scientific evidence that basil does anything in terms of like
repelling tomato hornworms. As to what is often touted for
doing or improving the flavor ofthe tomato, there is anecdotal
data that suggests it might helprepel thrips, and that maybe the
strong scent of the basil can help repel other insects.
(21:19):
And basil does attract pollinators.
This can actually be true of a lot of different strong scented
herbs and flowers, so this may not be specific to basil with
tomatoes. It doesn't mean again, that
these things aren't true, it just means that there isn't any
actual evidence. So there is no harm in planting
(21:40):
them together, but you just shouldn't rely on basil alone
for your pest control. So in addition to planting basil
in with my tomatoes, which I absolutely do, I absolutely do
this. I do think they go well together
and I will actually plant multiple varieties of basils.
So the green like Italian basils, sweet basils that we
(22:01):
harvest to, to sell in bunches of actual basil leaves.
I also plant different types of basil that maybe I'm not
harvesting to sell, but I'm allowing them to go to flower
because they do put off such beautiful flowers and a lot of
pollinators and other insects are attracted to that.
And of course that helps the tomatoes.
But also I am planting things like, you know, marigolds down
(22:23):
at the ends or in and amongst the the tomatoes.
And I am going to plant sunflowers down at the end of
that section of the garden to attract the birds.
And the birds are trying to pickoff the things like the tomato
hornworms that might actually bedamaging my tomatoes, but that
maybe the basil isn't repelling.I am not relying on just one
(22:44):
planting or one companion to do these jobs.
I am, you know, loading my basesand making sure that every
single thing that's out there has some sort of different
mechanism for helping me with these insect pests.
So no harm in planting them together, but don't rely on
basil alone for your pest control.
(23:04):
Another one would be porridge and planting that near squash or
tomatoes. Porridge flowers do attract
pollinators and they attract beneficial Wasps and some of
those beneficial Wasps are the ones that will predate on those
tomato hornworms. You may have seen images of
tomato hornworms with eggs laid on them.
(23:26):
It's fascinating to see. And what that is, is these
predatory Wasps have come in andhave laid their eggs on the
hornworms. And when those eggs hatch, then
they essentially eat the hornworms.
And so you're kind of disruptingthat hornworm reproduction cycle
right there. So, and there have been some
studies that do show if you weretomato hornworms on plants that
are planted near borage, You just have to remember that
(23:48):
borage grows very large, so you want to space it appropriately
to avoid shading anything nearby.
So it's fine to do them with thetomatoes because they're both
fairly tall. But if you're doing it near
squash, you want to do this likesort of appropriately, right?
I keep mentioning sunflowers andI use sunflowers to attract
birds that will predate on the insects in my garden.
(24:12):
And thereby I am helping to reduce the pests.
But I do shy away from planting anything too close to the base
of those plants because sunflower can be a highly
allelopathic plant. It's phytotoxic potential has
been shown on crops and weeds innot just laboratory settings,
(24:35):
but also in greenhouse and fieldtrials.
And they've done all kinds of tests on this with different,
you know, a variety of factors like the concentration of how
many sunflowers are growing and the different species and the
different genotypes. So, you know, again, sunflower
are another one that kind of gives off these, these root
exudates that are chemicals thatare going to inhibit the growth
(24:59):
of other plants in and around the base of the sunflowers.
Which means that sunflowers are a good crop to plant for
suppressing weeds, especially annual weeds, because it's going
to prevent them from coming up. But it may not be something that
you want to plant within a few feet of any crop that you
actually intend to harvest. Which it's kind of a shame
because, you know, we talked about the Three Sisters method.
(25:21):
And if you think about a sunflower, they have such real
good sturdy stalks. You would hope that it would be
something that you would be ableto use as like a natural trellis
like the corn in the three Sisters method.
But unfortunately, most crops are not going to be able to
handle the chemical signals or the chemicals that are being
released from those roots. And if they are something that
(25:44):
could handle those allelopathic properties, the other way a
plant could be allelopathic, meaning it is preventing the
growth of things near it is to be basically a nutrient hog.
Sunflower is a very demanding plant and it can usually out
compete anything that it is planted with.
So sunflowers have very deep taproots.
(26:08):
I did a whole episode on sunflowers and their ability to
be able to. I guess it wasn't a whole
episode specific to sunflowers, but it was talking about phyto
remediation, which is the ability to be able to draw
toxins and other contaminants out of the soil.
Sunflowers are fantastic for that and if they have that
ability then you know they have a very, very strong root system.
(26:31):
So they are going to out competejust about anything.
The only thing that I have really seen them not be able to
handle at least in my area is a heavy growth of hemlock plant.
Like we have hemlock out here that is just invasive and goes
crazy. And I had tried planting
sunflowers to kind of out compete the hemlock and the
(26:52):
hemlock just it takes over everytime.
So that's something that we havedealt with.
But sunflower great for suppressing weeds, especially
annual weeds, but you you may not want to plant any actual
harvestable crops anywhere near the base of them.
Now, sometimes a plant that we plant intending for it to help
can actually do the opposite. I'm all about experimenting with
(27:17):
companion plants to see what works and what doesn't work in
your garden in your experience. Again, we don't always have to
rely on these science research studies, et cetera, to show us
what works in our own garden. I just don't like to spread that
information to people once I seesomething works for me because
it may not work for somebody else if I just have anecdotal
(27:39):
information, right? But there are, you know, certain
cases where we know something doesn't work for very specific
reasons. For example, dill.
Dill attracts swallowtail caterpillars, which you know
actually it attacks this that tracks the butterfly and they
like to lay their eggs in the dill.
This also is in parsley as well,but dill specifically, and dill
(28:03):
also attracts aphids so you probably don't want to be
planting those near your tomatoes because you're
encouraging those caterpillars and you're encouraging aphids to
be in your tomatoes. Mature dill can also suppress
tomato growth first via that allelopathy early on.
So you know the early plants aren't so bad, but once they
(28:23):
start to go to flour then the dill can cause a problem.
So it's not usually a good idea to plant dill near your
tomatoes. Same thing goes with sunflowers.
Again, anywhere near beans. So, you know, I will plant
sunflowers along end rows in my garden.
It's usually the one thing that I don't plant in amongst
(28:44):
everything else. But if I'm going to plant beans,
they're going to be at the opposite end of that garden area
because sunflowers can actually attract stink bugs and they can
harbor seed maggots. And this is not something that
we want in our beans because beans are very susceptible to
the damage from those. They're great for pollinators,
the sunflowers are, but you justwant to make sure that you're
monitoring them closely near anyof those vulnerable crops.
(29:06):
Another one is fennel. Fennel also has allelopathic
compounds and it can inhibit thegrowth of a lot of vegetables,
most of them actually. So if you are growing fennel,
you likely want to plant it by itself.
And it's a great plant that you can put in a separate pollinator
bed and because it does again, attracts those things like
(29:28):
swallowtail butterflies. And so if you are growing fennel
as your crop to eat, then you want to keep it away from the
rest of your crops that it doesn't actually inhibit the
growth of the rest of your garden.
OK, so there are a few more plants that we may not want to
plant together just you know based on olelapathy or even just
(29:50):
direct competition. The first one is planting onions
or garlic in an amongst beans. So one of the things that we
get, one of the benefits that weget from planting beans or
anything else in the Allium or in the legume family, sorry, in
the legume family, is that beansand other legumes add nitrogen
(30:10):
to the soil through a symbiotic relationship with rhizobium
bacteria. These these bacteria form
nodules on the bean roots, so they convert atmospheric
nitrogen into a form that the plant can use through those
nodules. When the plant dies or when we
(30:31):
cut it down, we leave that root system in the ground, which
means those nodules are still inthe soil.
And then as they decompose, theyrelease that fixed nitrogen back
out into the soil. And that of course, helps enrich
the soil for future crops. If we plant onions or garlic,
any of our alliums next to our beans or near our legumes, it's
(30:55):
a bad idea because alliums release sulfur compounds and
Allison, which is an antibacterial compound.
And those compounds can actuallykill off the beneficial nitrogen
fixing bacteria that are doing that job for us.
That's those are the bacteria that the legumes need for that
(31:15):
nitrogen fixing. So not only is that going to
affect the plants ability, the bean plants ability to be able
to kind of store up that nitrogen for us and give us
those benefits, but it actually may interfere with the bean
plants growth itself. So we want to avoid planting
onions or garlic in and around near our beans.
Another one would be carrots anddill or parsnip.
(31:38):
These are all in the APACA family and so they can cross
attract carrot flies and also attract the same diseases.
So we don't want to group them together.
The same thing goes basically for other plant families.
So nasturtiums, for example, nasturtiums will repel a lot of
different pests, but nasturtiumsare in the brassica family.
(32:00):
And so it would be probably a bad idea to plant nasturtiums in
and amongst all of your brassicas because they're not
going to be very effective at the pests that we're worried
about in our brassicas, like thecabbage moths or other pests,
because the phytochemicals are all the same.
So This is why we generally don't want to plant things in
the same family all together. Same thing goes with like
(32:22):
potatoes and tomatoes. They're both in the nightshade
family, so they are both susceptible to the same fungal
and bacterial diseases, especially blight.
So we want to separate them to reduce that risk.
Does this mean that I'm not planting my brassicas all like
near each other? No, I'm still planting them in
beds that are close to each other because again, we talk
(32:44):
about this all the time. We're not farming on 1000 acres
here, right? And I mean, even I have more
room to plant than a lot of other people do.
But if you're gardening in your backyard, you only have a
limited amount of space. So you're obviously going to
have to be planting some of these plants close to each
other, right? So it's just important to,
again, use that companion planting to mix up all the
(33:05):
species. Tomatoes and corn, these are
both really heavy feeders and they're going to compete for
nutrients a lot of time. Plus corn can host the the corn
earworm, which is also known as a tomato fruit worm.
So that also targets tomatoes. We don't want those pests coming
in and landing on one and also being able to feed on the other.
(33:27):
So those can be, you know, both of the plants weak and it opens
them up to different pests and diseases.
So we don't want to plant those together either In terms of
companion planting with strategy, right?
This is where intercropping or interplanting comes into play.
We're going to talk next week about the strategies like really
dive deep into the kind of systematic version or way that
(33:52):
we can companion plant through intercropping.
It's based on timing, it's basedon spacing, it's based on plant
architecture, all of these different things.
But some of the ones, you know, just here briefly that we can
touch on that are really good examples are things like what we
already talked about the three sisters, right, corn, beans and
squash. The beans fix the nitrogen the
corn provides support the squashsuppresses the weeds.
(34:15):
And you can also deter like raccoons and stuff from getting
into your corn because the if you're using the squashes that
have like the spiky stems on them, that can actually help,
you know, keep those buggers from crawling in there and
trying to climb up the corn and and pull the corn down.
So lots of different benefits toeach other when they're being
planted together, planting fast growing crops with slow growing
(34:39):
ones. So radishes or lettuce being
planted in between longer maturing crops like the broccoli
or your Peppers, not only is maximizing space, it's also
reducing that weed pressure. So those are good companions
together. But again, when we're talking
about deterring pests, we're mixing up those chemical signals
by planting multiple plant families together.
(35:01):
So that is deterring the pests because they can't find their
preferred host nearly as easily,especially, again, appropriate,
inappropriate landings. They land on a radish and go,
oop, that's not what I wanted. I want to land on the carrot and
then they might land on the carrot and then they land again
and oops, back on a radish again.
Like it's it it resets that whole cycle.
So the more things that we can plant together that are not in
(35:22):
the same plant family, the better off we are.
This kind of inter planting, youknow, rows of of non host crops
not only visually confuses the pest, but it also, you know, can
confuse them in terms of like the texture and the landing on
them, right? So alternating rows of onions
and carrots that can mask each of those crops from their
(35:43):
respective pests like onion maggots and the carrot rust
flies, et cetera. This is why when I'm planting my
brassicas again, they are being planted near each other.
I might have one full bed that has all, you know, broccoli in
it. That bed right next to it may
also have cabbage in it. And then the one right next to
that might have cauliflower in it.
But they're not by themselves. They are not growing by
(36:06):
themselves ever in those beds. So even though those all attract
the same pests, I am inter planting those onions and those
lettuces and the the Elysium in and amongst them.
So it is still confusing those pests, right?
That is how you kind of get around the space issue when it
(36:26):
comes to growing your crops. If you can inter plant them and
confuse those pests, that's going to help.
To be most effective, we want tochoose crops that have different
growth rates and that also have different canopy shapes and we
don't want to overcrowd. This is probably the most
difficult part of this and something we're going to kind of
deep dive into next week. Intercropping works best when
(36:49):
you have a plan and you understand the mature size of
these plants and how they're going to affect each other when
they are all at maturity, whether or not they've already
been pulled or not and that sortof thing.
So we'll go into that a little bit more next week.
Companion planting absolutely works, right, whether or not
(37:15):
we're using it in terms of, you know, increasing our soil health
or protecting our, our, our soilor keeping weeds at Bay or in
terms of pest management. But it works best as part of an
integrated pest management strategy.
I will link to the IPM episode that I did earlier in the
(37:36):
season. But this means prioritizing
plant health and soil health, right?
Because again, our healthy plants and our healthy soil are
going to be much better at resisting those pests and being
able to bounce back once they are predated on and on
monitoring for that pest presence and keeping track of
those lifestyles, life cycles sothat we know when and how those
(37:59):
pests are operating. And then combining all of this
companion planting with using physical barriers and natural
predators when appropriate. Doing your homework on which
companions actually have evidence behind them is a really
good place to start. And is also going to sort of
(38:19):
weed out which ones might just be garden folklore.
A lot of plants do express insecticidal traits.
The key is to use them for your benefit and use them on plants
that are very dissimilar and that way they produce different
phytochemicals. So again that you know that
(38:40):
reference to the nasturtiums, they do repel pests, but they
are in the Brassica family. So maybe don't use them to try
to deter pests from others in that family.
Put them in with something else like maybe your squash plants.
And if you have, you know, or, or just use them as a trap crop,
if you have tried a companion planting combo that works for
(39:01):
you, there is no reason not to continue it if you know it's
working. And you can go ahead and share
that, you know, let me know. I would love to, you know, hear
some real world examples of things that have worked for you.
If you have tried a companion planting that totally flopped
and maybe you didn't realize whyit flopped until later on or
(39:22):
even just now listening to this episode and realizing, oh,
nasturtiums attract aphids and Iwas trying to get rid of aphids
but I put them in and they were,oh, now I understand.
Go ahead and let me know that too.
I would love to hear about it again.
If I hear a bunch of real world examples from people, I am super
happy to, you know, update everybody in a future episode to
(39:42):
let them know like, hey, this has worked for some people,
maybe it'll work for you. Just remember, when you are
dealing with anecdotal companionplantings, what works for one
person may not work for another one.
So do not rely on any of these companion planting suggestions
as your sole way to keep insect pests at Bay in your garden.
(40:04):
Make sure it's part of an integrated plan and that you
have more than one way to keep away those pests.
Until next time, my gardening friends, keep on cultivating
that dream garden and we'll talkwith you soon.
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