You can physically scoop it out with a fine mesh net.

No, it floats on the water surface and absorbs nutrients directly from the water column.

Plant guide

Duckweed.

Lemna minor

Pronounced LEM-nuh MY-nor

Also known as Boggart, Common Duckweed, Duckweed, Groves, Jenny Greenteeth, Karearea, Least Duckweed, Lesser Duckweed

Duckweed is a tiny, free floating aquatic plant that covers the surface of still water. It grows rapidly and helps absorb excess nutrients from the water. You will often see it in ponds or slow moving streams.

At a glance

Care level: Easy
Plant type: Aquatic
Light: Full sun to partial shade
Indoor light: Bright indirect
Water: Every 0 days
Mature size: 0.5 centimeters
Growth rate: Fast
Hardiness: USDA 4 to 10
Bloom time: Rarely blooms in summer

Care

Keep this plant in still water to prevent it from being submerged or washed away. Watch for yellowing fronds which might indicate a nutrient deficiency. It spreads very quickly so you may need to scoop out excess to keep it from taking over.

Watering: This plant must float on the water surface at all times.
Feeding: Add a small amount of aquatic plant fertilizer if growth slows down.
Pruning: Remove excess growth with a net to maintain surface area.
Repotting: Repotting is not applicable as it is a free floating plant.
Soil: None, aquatic
Soil pH: 6.0 to 7.5
Temperature: 5 to 30°C
Humidity: 70 to 100%

Safety

People: It is generally considered non toxic, but its tendency to bioaccumulate contaminants makes it unsafe to eat from unknown water sources.
Children: Small children should be supervised around open water where this plant grows to prevent accidental ingestion of potentially contaminated water.
Edibility: Duckweed can absorb heavy metals and toxins from polluted water, so never consume it from the wild.

How to identify it

Tiny green oval shaped fronds
Single root hanging beneath
Forms dense mats on water
Lacks distinct stems or leaves

Height: 0 to 0.01m
Spread: 0.01 to 1m
Leaves: bright green, deciduous
Flowers: white, green, 0.1 to 0.2cm

Problems to watch for

By symptom

Plant problems by symptom

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Growing it

Propagation: division
When to plant: spring, summer

Keep duckweed in check by pairing it with submerged oxygenators that help balance water chemistry.

Grows well with

Water Hyacinth · They both thrive in similar nutrient rich aquatic environments.
Hornwort · This submerged plant provides oxygen while the duckweed shades the surface.

Similar species

Giant Duckweed · It is larger and has multiple roots hanging from each frond.
Watermeal · These are even smaller and lack roots entirely.

Science

Family: Araceae
Genus: Lemna
Order: Alismatales
Class: Liliopsida
Native range: Cosmopolitan, found in temperate and tropical regions worldwide.
Conservation: It is a common, widespread species and is not of conservation concern.

It thrives in still or slow moving nutrient rich water where it forms dense mats that shade the water below.

Value to wildlife: provides cover for aquatic life, waterfowl food source
Pollinators: beetles
Uses: water filtration, aquarium cover, livestock feed

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 7/9
Temperature: 6/9
Moisture: 9/9
Nutrients: 8/9

Taxonomy resolved against GBIF.

Questions people ask

How do I control it?: You can physically scoop it out with a fine mesh net.
Does it need soil?: No, it floats on the water surface and absorbs nutrients directly from the water column.

Where the name comes from

The name Lemna comes from the Greek word for a swamp plant, while minor refers to its small size.

Good to know

It is a free floating aquatic plant with a single tiny root hanging from each frond.
Duckweed is a highly efficient nitrogen and phosphorus remover.
The entire plant body is called a frond.
It is often used in research as a model organism for plant biology.

Keep your duckweed growing

This page is a general guide. Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked.

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.