Ruud Kleinpaste: What to look for in a fertiliser

Warmer soils – new growth – plants wake up slowly – cells become active 

Plants, trees, shrubs, mosses, climbers perform LOTS of ecosystem services; One of the most important ones: Photosynthesis. They absorb CO2 from the air, run water with dissolved nutrients through roots and “vascular systems” (tiny pipes in stems, branches, veins, etc) and it all ends up in the leaves; green leaves. 

The reason those are green is because they contain cells with all sorts of active molecules, especially chlorophyll. This Chlorophyll, concentrated in chloroplasts is where all the action is: 

Water, nutrients, CO2 and sunlight (literally solar energy!) combine to manufacture carbohydrates (sugars) and Oxygen (O2) which we breathe in. 

Ecosystem Service: Take CO2 out of the air and turn it into Oxygen, while the Carbon ends up in the soil when leaves fall to the ground and are recycled by bugs, fungi, bacteria etc 

Simple, eh? 

To create a healthy, functional garden (or forest) with trees, shrubs, plants etc, we need to make sure that all elements are provided and that includes nutrients (fertilisers). 

If you go into a garden centre you’ll notice that most fertiliser containers give you an “N-P-K” ratio for the contents. Those three chemicals (Nitrogen, Phosphorus/Phosphates and Potash (the Latin name is “Kalium” – hence the “K”) are the macro-nutrients that plants take up in rather large quantities. They are, indeed, the most important fertiliser compounds needed for healthy plant growth. 

Trace elements (needed in much smaller quantities) are Magnesium, Iron, Manganese, Calcium, boron, Zinc, molybdenum, selenium, etc 

They are important certainly if they are lacking in the soil! (so don’t ingnore them). 

Let’s concentrate on the N, P and K. 

Nitrogen is the stuff that makes plants green; this molecule provides the building blocks for Chlorophyll. If you have plants that are valued for their leaves and green stems (grass, lawns, lettuce, ornamental trees and shrubs) they will need more N and than – say – P or K; 

Plants with important roots (carrots, parsnips, potatoes) and other underground organs that will grow as they explore for “food in the dark” need a little bit more P to do just that. 

And the K (Potash) is for reproduction. 

Plant reproduction is of course mostly through flowers, which are pollinated and hence become fertilised to produce seeds and fruits which, when deposited on soil, will yield new seedlings. 

That means that flowering plants and fruiting trees, shrubs, vines and berry bushes, really appreciate an extra dollop of potash, just to keep the cool stuff coming. 

Knowing the right fertiliser mix truly makes a difference; 

Don’t be tempted to “over-dose” your plants as too much shows up in certain symptoms that make your plants look “sick” 

My tactic is “Small amounts and Often” 

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