Category: Aquarium Plants

Fertilizing Substrates

In preparing my tanks for the May 2, 2026 Expo (See previous post), I noticed that the plants in the tank with a potting soil substrate were not growing as enthusiastically as plants in the other tank, which were in garden soil. What to do? Good rooted plant growth is key, and fertilizing the water just encourages algae. Unwilling to tear tank down and put in a new substrate… In a panic, I finally tried something mentioned many years ago on Aquatic Plant Central–insert frozen cubes of soil into the soil underlayer. So I froze cubes of my rich garden soil (Piedmont clay topsoil plus bone meal) and did my best inserting the cubes into the soil before they thawed. For good measure, I also inserted small pieces of 3 houseplant fertilizer sticks. Also replaced rock and attached Anubias nana with the beautiful Red Tiger Lotus. Results encouraging!

Cubes of Wet Garden Soil ready for freezing. I inserted these into a potting soil underlayer in the 10 gal tank where rooted plants were not growing that well.
I also inserted pieces from three of these sticks throughout the potting soil underlayer.
Redo of the Tank with added soil cubes, fertilizer pieces, and a Red Tiger Lotus in the center. Afterwards, a 30% water change and a little washed sand and gravel took care of the substrate disruption. Photo shows tank one day after the redo. It’s fun to play with soil!