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October 30, 2025 62 mins

 Have you ever dreamed of turning a simple fish tank into a lush underwater jungle? Or maybe you're like me, and you have a partner who isn't really into houseplants but is fascinated by those YouTube videos about turning aquariums into these swaying underwater jungles?

You or your partner are gonna love this Best of Growing Joy Replay Episode when, a few years ago, I sat down with Karen Randall. She's the author of Sunken Gardens and an aquatic gardening expert, and we break down everything you need to know to start your first planted aquarium. You'll gain the confidence to create a thriving mini ecosystem underwater right on your countertop!

 

In this episode, we learn:

  • [01:06] Introducing Karen
  • [03:33] What to expect from this conversation
  • [05:20] How Karen became the plant lady she is today
  • [07:40] The importance of knowing your plants’ natural habitat
  • [08:42] Why are planted aquariums becoming popular again?
  • [10:33] Basic houseplants vs. aquatic plants
  • [12:04] How do you trade aquatic plants?
  • [13:33] What are aquatic plants and how do they grow underwater?
  • [15:04] The different types of aquatic plants
  • [19:48] How are emersed and submersed aquarium plants different
  • [21:24] The basic requirements for a planted aquarium with live plants
  • [23:43] What does ‘cycled’ mean?
  • [25:57] Why do you need to let your plants settle in the aquarium before introducing fish?
  • [28:43] Where to get bacteria that your aquarium needs
  • [30:04] Three uses of filters in your aquarium
  • [33:07] How to prep your plants for winter
  • [34:51] Learn from a horticulturist!
  • [37:06] What water to use in your aquarium
  • [38:31] How to figure out the water you have at home
  • [39:52] Troubleshooting your aquarium water
  • [42:03] Why do you need to change the water in your aquarium?
  • [43:17] Using fertilizer in your aquarium
  • [45:08] What type of substrate works best for your aquarium?
  • [50:23] Aquarium lighting and the basics
  • [53:26] The most important lighting factor for your aquarium
  • [56:56] Karen’s aquarium supply recommendations
  • [58:26] How to transition to a bigger tank
  • [01:00:11] Are CO2 systems worth it?
  • [01:03:14] How do you select plants for your aquarium?
  • [01:05:24] Top 5 best aquatic plants for beginners
  • [01:11:41] Maria’s plans for her own planted aquarium

 

Mentioned in our conversation:

 

Do you want to learn more about aquascaping?

Check out the full show notes and blog to discover how aquatic plants can bring life and joy into your space!

 

Follow Karen:

Planted Aquarium Website
Facebook
Vivarium/Terrarium Website
Planted Nano and Betta Tank Facebook Group

 

 

Follow Maria and Growing Joy:

Order my book: Growing Joy: The Plant Lover's Guide to Cultivating Happiness (and Plants)by Maria Failla, Illustrated by Samantha Leung

Join the Bloom and Grow Garden Party Community Platform & App AKA the plantiest and kindest corner of the internet! Get your FREE 2-week trial here!

Take the Plant Parent Personality Quiz (Get the perfect plants, projects and educational resources for YOUR Lifestyle)

Support Bloom and Grow Radio by becoming a Plant Friend on .css-j9qmi7{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:row;-ms-flex-direction:row;flex-direction:row;font-weight:700;margin-bottom:1rem;margin-top:2.8rem;width:100%;-webkit-box-pack:start;-ms-flex-pack:start;-webkit-justify-content:start;justify-content:start;padding-left:5rem;}@media only screen and (max-width: 599px){.css-j9qmi7{padding-left:0;-webkit-box-pack:center;-ms-flex-pack:center;-webkit-justify-content:center;justify-content:center;}}.css-j9qmi7 svg{fill:#27292D;}.css-j9qmi7 .eagfbvw0{-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;color:#27292D;}


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