Troubleshooting
Lawn Pennywort problems — and how to fix them
Lawn Pennywort (Hydrocotyle sibthorpioides) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Upward growth instead of carpeting
Caused by insufficient light or lack of CO2; increase PAR and/or inject CO2 at 15-25 ppm to encourage horizontal spreading.
Melting or browning after planting
Transition melt as emersed-grown stock adapts to submersed conditions; trim melted portions and allow 2-4 weeks for new submersed growth to establish.
Algae smothering the carpet
Keep nitrates below 10 ppm, maintain strong light, and ensure good CO2 to keep growth fast enough to outcompete algae.
Carpet becoming thin and patchy
Usually nutrient deficiency (iron or macronutrients); increase root tab coverage and dose liquid fertiliser weekly.
Snail damage
Some snail species graze on delicate leaves; reduce snail population or switch to snail-safe algae-eating species (Nerite snails rarely touch healthy plants).
Prevent lawn pennywort problems before they start
Most lawn pennywort issues are care-mismatch, not bad luck. Dial in the basics:
Lawn Pennywort problems — FAQ
Why is my lawn pennywort upward growth instead of carpeting?
Caused by insufficient light or lack of CO2; increase PAR and/or inject CO2 at 15-25 ppm to encourage horizontal spreading.
Why is my lawn pennywort melting or browning after planting?
Transition melt as emersed-grown stock adapts to submersed conditions; trim melted portions and allow 2-4 weeks for new submersed growth to establish.
Why is my lawn pennywort algae smothering the carpet?
Keep nitrates below 10 ppm, maintain strong light, and ensure good CO2 to keep growth fast enough to outcompete algae.
Why is my lawn pennywort carpet becoming thin and patchy?
Usually nutrient deficiency (iron or macronutrients); increase root tab coverage and dose liquid fertiliser weekly.
Why is my lawn pennywort snail damage?
Some snail species graze on delicate leaves; reduce snail population or switch to snail-safe algae-eating species (Nerite snails rarely touch healthy plants).