Has anyone used Riccia (Riccia fluitans) as a living wick/top-dressing for indoor plants?
I accidentally got a tuft of Riccia with some aquarium trimmings and pressed it onto the damp rim of a self-watering planter with LECA. It anchored to the clay in a week and formed a springy, bright green mat. Unexpected side effects:
- The LECA surface stays evenly moist but not soggy, and fertilizer crusting stopped.
- Fungus gnat activity dropped around that pot.
- Midday it actually “pearls” emersed under lights, and there’s a faint cool, humid microbubble right above the surface.
- The aroid in that pot pushed new feeder roots into the top layer.
Now I’m wondering if we’ve been sleeping on Riccia as a living humidity buffer/biowick indoors. Questions for anyone who’s tried similar:
- Longevity emersed: Can Riccia run long-term on capillary moisture without a lid, or does it inevitably melt unless RH stays >60-70%? What PPFD/photoperiod keeps it compact instead of fluffy?
- Nutrients and EC: Does it compete meaningfully with the plant for nitrogen, or act like a micro biofilter that evens out salts? Any EC/TDS or hardness ranges where it sulks emersed?
- Gnat pressure: Does the dense mat block emergence and egg-laying for you, or does the constantly damp surface make gnats worse?
- Airflow and cleanliness: Tips to avoid cyanobacteria/algae films on the mat? Gentle fan vs intermittent misting? Are brief H2O2/alum dips safe for Riccia if contamination appears?
- Pairings: Good companions? I’m thinking jewel orchids, anthurium seedlings, peperomia, carnivorous plant trays. Bad pairings where it outcompetes moss or stays too wet?
- Mounting tricks: Best way to keep it flat and tidy-hairnet/mesh, thread on lava rock, ceramic wick strips, or pressed into LECA? How often do you trim to prevent it from lifting off?
- Sanitation: If sourced from aquaria, how do you clean it to avoid sneaking in snails/hydra/planaria before introducing to housepots or terrariums?
- Bonus: Has anyone measured a temperature or RH bump above a Riccia mat, or seen improved root health from the oxygenated, moist interface?
My current setup: 12h at 100 PPFD, gentle airflow, 55-65% RH, 22-24°C, semi-hydro with 250 µS/cm tap plus 50 ppm N weekly. Two weeks in, the mat is 5-7 mm thick and stable.
If a few folks are game, I’d love to compare a simple A/B: same plant and potting, with and without a Riccia cap, and track moisture, gnats, and growth over a month. Anyone up for it-or already tried this?