Hydrocharis morsus-ranae (Frogbit) care

Light

Aim for at least 4-6 hours of direct sun on the leaves. Prefers full sun to light shade at the water surface; bright light keeps leaves compact and encourages flowering and dense, healthy rosettes. If your only bright window faces south, that's perfect for hydrocharis morsus-ranae — same window any aroid would fry on.

Watering

Watering hydrocharis morsus-ranae: free-floating; keep on the surface of still or slow water. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Not rooted in soil; it floats with dangling roots absorbing nutrients from the water. Thrives in calm, nutrient-rich ponds and dislikes turbulence and strong current.

Soil and pot

Hydrocharis morsus-ranae grows best in none (free-floating). Needs no substrate; nutrients are taken directly from the water column by its trailing roots. A muddy pond bottom helps only as a nutrient reservoir. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Hydrocharis morsus-ranae sits happiest at around 100% (aquatic) humidity and 5-25°C (41-77°F). An aquatic floater for which ambient humidity does not apply; leaves rest on the water surface and flowers emerge just above. If you keep the room above 5 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed hydrocharis morsus-ranae sparingly. No direct feeding needed; it draws all nutrients from the water. In a very lean pond it may grow slowly, but adding fertiliser usually just triggers algae rather than helping the plant. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on hydrocharis morsus-ranae in the Growli community. Each is annotated with the most common cause so you know where to start.

• Invasive spread — It is a regulated invasive in parts of the US and Canada; sale or release may be prohibited. Keep it in a contained pond and bin surplus rather than dumping it.
• Overcrowding the surface — It multiplies quickly and can blanket a small pond, shading submerged plants and lowering oxygen; scoop out excess regularly.
• Disappearing in autumn — Leaves rot and the plant overwinters as sunken turions; this is normal dormancy, not death, and it reappears in spring.
• Aphid clusters — Aphids gather on the small leaves; hose them into the water for fish or net the affected rosettes rather than spraying.

Propagation

Spreads effortlessly by detaching daughter plants along its surface runners; simply lift and move a rosette. It also self-perpetuates through overwintering turions each spring. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Hydrocharis morsus-ranae is mildly toxic to pets. Hydrocharis morsus-ranae is not individually listed on the ASPCA Toxic/Non-Toxic Plants database, so its pet status is uncertain. While not reported as a significant toxin, treat it as a non-food plant, discourage pets from eating it, and verify with a vet if ingestion is suspected. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Hydrocharis morsus-ranae deep-dive guides

Every aspect of hydrocharis morsus-ranae care, each with its own calibrated guide:

• Hydrocharis morsus-ranae watering schedule
• Hydrocharis morsus-ranae light requirements
• Best soil mix for hydrocharis morsus-ranae
• Hydrocharis morsus-ranae fertilizing guide
• When to repot hydrocharis morsus-ranae
• How to propagate hydrocharis morsus-ranae
• Hydrocharis morsus-ranae growth rate & size
• Hydrocharis morsus-ranae cold hardiness
• Hydrocharis morsus-ranae temperature & humidity
• Is hydrocharis morsus-ranae toxic to cats & dogs?
• Is hydrocharis morsus-ranae toxic to cats?
• Is hydrocharis morsus-ranae toxic to dogs?
• Getting hydrocharis morsus-ranae to bloom

Featured in these plant shortlists

Hydrocharis morsus-ranae qualifies for 5 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best flowering houseplants — Indoor plants grown for their blooms — selected from the flowering species in Growli’s plant-care library.
• Best small & tabletop houseplants — Compact houseplants that stay under about 40 cm — desk, shelf and windowsill plants that never outgrow a small space.
• Best houseplants for full sun — Houseplants that want direct sun — the species for a hot south or west-facing windowsill where shade-lovers scorch.
• Best houseplants for a cool room — Houseplants that tolerate cool conditions down to about 10°C — for an unheated spare room, hallway, porch or a home kept cool.
• Best fast-growing houseplants — Houseplants documented as fast or vigorous growers — quick to fill a pot, cover a pole or trail down a shelf.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Hydrocharis morsus-ranae is also known as Frogbit, Common Frogbit, and European Frogbit.

• Peace lily care — light, water and common problems
• Bird of paradise care — light, water and common problems
• Hoya care — light, water and common problems
• All 5561 plant care guides in the Growli library