Ivy-leaved Duckweed (Star Duckweed) care

Light

Picture the indirect light an east-facing window gives mid-morning — that's the brightness ivy-leaved duckweed grows fastest in. Grows well in moderate to bright indirect light, either submerged in pond or aquarium. Tolerates partial shade better than most duckweeds. Avoid very deep shade which reduces growth; very intense direct light combined with warm water promotes surface drift and competitive algae. You'll know it's right when new leaves come out the same size and colour as the established ones. Smaller, paler new leaves = move closer to the window.

Watering

Aim for permanently submerged for ivy-leaved duckweed, but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Remains submerged just below the water surface in still or slow-moving freshwater, typically 10–60 cm deep. Prefers clean, cool, slightly nutrient-rich water. Rises to the surface only when producing tiny flowers.

Soil and pot

Ivy-leaved Duckweed grows best in free-floating — no substrate required. Lemna trisulca is a free-floating aquatic with rootlets that hang in the water column absorbing nutrients directly. No sediment or substrate needed. Grows in ponds, lakes, aquaria, and slow streams. 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

Ivy-leaved Duckweed sits happiest at around 100% (aquatic) humidity and 4–24°C (39–75°F). Fully submerged aquatic; atmospheric humidity is irrelevant to plant health. Water quality — pH 6.5–8.0, low turbulence, adequate light — is the key environmental factor. If you keep the room above 4–24°C 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 ivy-leaved duckweed sparingly. No fertiliser required. Absorbs dissolved minerals and nitrates directly from the water column. In aquaria with fish waste, no supplemental feeding is needed. Excessive nutrients can cause nuisance growth. 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 ivy-leaved duckweed in the Growli community. Each is annotated with the most common cause so you know where to start.

• Surface mat formation at flowering — When plants briefly surface to flower, they can temporarily form a surface mat. This is a natural behaviour; skim lightly if it shades submerged planting or fish, but avoid removing all surface material.
• Loss in high-flow conditions — Unlike surface duckweeds, Lemna trisulca can be swept away or broken apart in moderate currents. Suitable only for still or very slow-moving water — ponds, lake margins, and aquaria with low pump flow.
• Competitive exclusion by Lemna minor — If common duckweed (Lemna minor) is also present, it can outcompete the submerged trisulca at the surface. Remove surface duckweed periodically to allow light penetration to the submerged colonies.

Propagation

Vegetative budding — daughter fronds bud off from parent fronds continuously. Transfer a handful of colonies to any suitable water body. Spreads naturally via waterfowl and water movement. 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

Ivy-leaved Duckweed is pet-safe. Lemna trisulca is not listed as toxic by ASPCA. Duckweeds (Lemnaceae) have no documented toxic principles and are widely consumed by waterfowl and fish. Considered safe in aquatic ecosystems shared with animals. 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.

Ivy-leaved Duckweed deep-dive guides

Every aspect of ivy-leaved duckweed care, each with its own calibrated guide:

• Common ivy-leaved duckweed problems & fixes
• Ivy-leaved Duckweed watering schedule
• Ivy-leaved Duckweed light requirements
• Best soil mix for ivy-leaved duckweed
• Ivy-leaved Duckweed fertilizing guide
• When to repot ivy-leaved duckweed
• How to propagate ivy-leaved duckweed
• How to prune ivy-leaved duckweed
• What's eating my ivy-leaved duckweed?
• Ivy-leaved Duckweed growth rate & size
• Ivy-leaved Duckweed cold hardiness
• Ivy-leaved Duckweed temperature & humidity
• Is ivy-leaved duckweed toxic to cats & dogs?
• Is ivy-leaved duckweed toxic to cats?
• Is ivy-leaved duckweed toxic to dogs?
• Getting ivy-leaved duckweed to bloom

Featured in these plant shortlists

Ivy-leaved Duckweed qualifies for 12 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best pet-safe houseplants — Houseplants the ASPCA lists as non-toxic to cats and dogs — every one verified against the ASPCA toxic and non-toxic plant list.
• Best low-light houseplants — Houseplants that need no direct sun and cope with a north-facing room or a spot well back from a window.
• Best plants for a north-facing window — Houseplants for a north-facing window: bright, even, indirect light and no scorching direct sun. Each pick verified against its documented light needs.
• Best pet-safe low-light plants — Non-toxic to cats and dogs AND happy with no direct sun — the two hardest constraints to satisfy at once.
• Best trailing & climbing houseplants — Vining and trailing houseplants for shelves, hanging pots, and moss poles — selected by growth habit.
• Best flowering houseplants — Indoor plants grown for their blooms — selected from the flowering species in Growli’s plant-care library.
• Best pet-safe trailing & hanging plants — Trailing and climbing plants the ASPCA lists as non-toxic to cats and dogs — safe for shelves and hanging pots in a pet home.
• Best pet-safe flowering plants — Flowering houseplants the ASPCA lists as non-toxic to cats and dogs — colour and blooms in a pet home, without the worry.
• 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 pet-safe bedroom plants — Non-toxic to cats and dogs and happy in lower light — calming greenery for a bedroom where a pet often sleeps too.
• Best cat-safe plants — Houseplants the ASPCA lists as non-toxic to cats (and dogs) — safe greenery for a home with a curious cat.
• Best dog-safe plants — Houseplants the ASPCA lists as non-toxic to dogs (and cats) — safe greenery for a home with a curious dog.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Ivy-leaved Duckweed is also commonly called Ivy-leaved Duckweed or Star Duckweed.

• Starflower care — light, water and common problems
• Large-flowered Bellwort care — light, water and common problems
• Sessile Bellwort care — light, water and common problems
• All 8452 plant care guides in the Growli library