Azolla caroliniana (Carolina Mosquito Fern) is a fast-growing, floating aquatic fern valued for its delicate, feathery foliage that ranges from green to reddish-bronze, especially in cooler weather. Forming dense mats on the surface of ponds or slow-moving water, it provides excellent cover for aquatic life while suppressing algae growth. Its ability to fix nitrogen also makes it useful as a natural water improver and green manure in rice paddies.

Why we like it

• Attractive floating fern with foliage that turns bronze-red in cool seasons

• Forms dense mats, helping to suppress algae

• Provides shelter for fish and aquatic insects

• Can improve water quality through nitrogen-fixing

What to know

• Prefers still or slow-moving freshwater

• Thrives in full sun to partial shade

• Can spread rapidly; may require thinning to prevent overgrowth

• Not frost hardy; dies back in cold climates but can regenerate from spores

Foliage Colour
Green to bronze-red

Growing months
Spring to autumn (dies back in winter in colder regions)

Height and Spread
Height: Floating mat, only a few cm thick
Spread: Can cover large water surfaces rapidly