Fertilising guide
How to fertilise Ivy-leaved Duckweed (Lemna trisulca)— schedule & NPK
Also called Ivy-leaved Duckweed, Star Duckweed.
More about ivy-leaved duckweed
About Ivy-leaved Duckweed
Lemna trisulca · also called Ivy-leaved Duckweed, Star Duckweed · flowering
Ivy-leaved Duckweed is a distinctive submerged duckweed native to Europe, Asia, and North America, forming translucent pale-green fronds connected in branching chains beneath the water surface. Unlike other duckweeds, it stays submerged until flowering. An excellent oxygenator and fish food plant for wildlife ponds and aquaria. Hardy and low-maintenance.
Growth habit: Submerged, free-floating aquatic perennial; fronds ovate-lanceolate 5–15 mm, linked in branching colonies resembling ivy; rootlets hanging freely in water.
What fertiliser ivy-leaved duckweed actually wants — and why
Ivy-leaved Duckweed is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for ivy-leaved duckweed: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed ivy-leaved duckweed, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For ivy-leaved duckweed:
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. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when ivy-leaved duckweed is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for ivy-leaved duckweed
Half strength is the safe default for ivy-leaved duckweed — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water ivy-leaved duckweed first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the ivy-leaved duckweed watering schedule.
Signs you are over-feeding ivy-leaved duckweed
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for ivy-leaved duckweed:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding ivy-leaved duckweed
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full ivy-leaved duckweed care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of ivy-leaved duckweed with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for ivy-leaved duckweed
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising ivy-leaved duckweed — frequently asked questions
What fertiliser does ivy-leaved duckweed need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Ivy-leaved Duckweed is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed ivy-leaved duckweed?
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. 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. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for ivy-leaved duckweed?
Half strength is the safe default for ivy-leaved duckweed — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding ivy-leaved duckweed look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding ivy-leaved duckweed year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of ivy-leaved duckweed?
Flush the pot of ivy-leaved duckweed with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Ivy-leaved Duckweed care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water ivy-leaved duckweed — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise starflower
- How to fertilise large-flowered bellwort
- How to fertilise sessile bellwort
- All 8452 fertilising guides in the Growli library