Canadian waterweed
Elodea canadensis · Hydrocharitaceae
The gardener's calendar
Ideal time to plant canadian waterweed: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Scientific name
- Elodea canadensis
- Family
- Hydrocharitaceae
- Type
- Submerged aquatic plant
- Growth
- Very fast
- Hardiness
- Very hardy (down to -15°C)
- Origin
- North America
- Planting depth
- 30 to 150 cm
Care
Aquatic environment
Waterweed is a fully submerged plant that develops in freshwater. It absorbs its nutrients directly from the aquatic environment through its stems and leaves. No irrigation needed: it naturally thrives in continuous immersion and develops best in water that is stable in temperature and chemical composition.
Light
Prefer a location with good light to encourage its growth and photosynthesis. It tolerates partial shade but grows more vigorously in moderate to bright light, particularly in a pond or aquarium close to an appropriate natural or artificial light source.
Substrate and water
Waterweed roots easily in sand, fine gravel, or silt. Soft water, slightly acidic to neutral, is ideal. It accepts a certain range of hardness but prefers lightly mineralized water. Adding carbon dioxide can speed up its growth in enclosed environments like aquariums.
Control and maintenance
Trim stems regularly to limit its very rapid expansion, particularly in ponds or aquariums. Remove excess portions to prevent it from choking out other aquatic plants. This pruning stimulates branching and maintains a balanced form.
Nutrition
In an aquarium, a diluted complete liquid fertilizer applied regularly supports its growth. In a natural pond, the water generally contains sufficient nutrients. Watch for iron deficiencies (yellowing of young leaves) and supplement if necessary with an appropriate nutrient booster.
Pests and problems
Waterweed is generally robust. It can accumulate filamentous algae if there are excess nutrients or excessive light. Limit the presence of aquatic snails that nibble its leaves. Regularly remove portions that turn brown or rot to maintain water quality.
Did you know?
Accidentally introduced to Europe in the 19th century, Canadian waterweed spread so rapidly through canals and rivers that it nearly paralyzed the entire French hydraulic network! Considered a formidable invasive species, it remains highly valued in aquarium keeping and for oxygenating ponds, where it can produce up to 20 times its own weight in oxygen per day.
Where to buy it
Best planted in spring or autumn, away from frost and heatwaves. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September, October.
Add this plant to my garden →Plants from the same family
- Halophila decipiensHalophila decipiens
- Halophila spinulosaHalophila spinulosa
- Halophila tricostataHalophila tricostata
- Halophila capricorniHalophila capricorni
- FrogbitHydrocharis morsus-ranae
- Nuttall's waterweedElodea nuttallii
Tips generated and checked by Viridia — adapt them to your local climate.