TankBud

Canadian waterweed

Elodea canadensis

Also known as Canadian pondweed, American waterweed, Common waterweed

FreshwaterStemCuttingsFragmentation

Canadian waterweed (Elodea canadensis)
Christian Fischer · CC BY-SA 3.0

Care at a glance

Light
Low light
CO2
No CO₂ needed
Temperature
39–75°F
4–24°C
Max height
23.6 in
60 cm
Growth rate
Fast
Placement
Background
Type
Stem
pH
6.5–8.0
Hardness
5–20 dGH
Spread
2 in (5 cm)
Nutrient uptake
Water column
Growth region
Submersed
Difficulty
Beginner
Family
Hydrocharitaceae
Origin
Native to lakes, ponds, and slow rivers across temperate North America.

Overview

Canadian waterweed is a hardy beginner stem plant for the background of a cool tank.

Did you know

Canadian waterweed is a classic plant for demonstrating photosynthesis in classrooms. It was one of the first aquatic plants used that way.

Caring for Canadian waterweed

Plant the stems loosely in the substrate, or leave them floating. Canadian waterweed roots loosely and takes most of its food straight from the water, so a liquid fertilizer does more for it than root tabs.

It is a low-light plant and grows without added CO2. It prefers cool water, from 39 to 75°F (4 to 24°C), and can struggle in warm tropical setups.

It grows fast enough to soak up excess nutrients and help fight algae. Trim it as needed and replant the cut tops. Pieces that break off keep growing, so pulling a clump apart spreads it.

Good to know

Canadian waterweed belongs to the frogbit family, Hydrocharitaceae. It is distinct from the similar-looking Egeria densa, which sits in a separate genus. Its slender, brittle stems are densely set with small, dark green leaves in whorls of three. Plants are either male or female, and outside North America almost all spread is by fragmentation rather than seed.

In the wild

Canadian waterweed is native to lakes, ponds and slow rivers across temperate North America. It grows in cool water and often forms thick underwater stands. It is a serious invasive species in Europe, Asia and Australia, so never release it into the wild.

Common questions

Does Canadian waterweed need to be planted in the substrate?

Yes. Strip the leaves from the lower part of each stem, then push the stems into the substrate one at a time, a little apart.

Does Canadian waterweed need CO2?

No. Canadian waterweed grows well without added CO2 and suits a low-tech tank.

How much light does Canadian waterweed need?

Canadian waterweed is a low-light plant, and the light that comes with a standard tank kit is enough for it.

Does Canadian waterweed need root tabs?

No. Canadian waterweed takes most of its nutrients from the water, so a liquid fertilizer does more for it than root tabs.

How do you propagate Canadian waterweed?

Canadian waterweed propagates by cuttings and fragmentation. Cut off the top of a stem and replant it, and the stump left behind grows new shoots. Pieces that break off keep growing, so pulling a clump apart spreads it.

How tall does Canadian waterweed grow?

Canadian waterweed grows to about 23.6 in (60 cm) tall. It grows fast, so expect to trim it often.

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