Azolla (water fern) Azolla pinnata
Azolla (water fern) (Azolla pinnata) is an evergreen perennial groundcover in the Salviniaceae family, native to Asia and tropical Africa. It grows 1–3 cm (0–1 in) tall and 2–5 cm (1–2 in) wide, wants part sun to part shade and high water, and is hardy to about 5 °C (41 °F). Space plants about 5 cm (2 in) apart.
Plan Azolla (water fern) in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Azolla (water fern) at a glance
| Type | Perennial groundcover, evergreen |
|---|---|
| Family | Salviniaceae |
| Mature height | 1–3 cm (0–1 in) |
| Mature spread | 2–5 cm (1–2 in) |
| Spacing | 5 cm (2 in) centre to centre |
| Sun | Part sun to part shade, at least 4 h of direct sun a day |
| Water | High; drought tolerance none, waterlogging tolerance high |
| Soil pH | 5–7 |
| Cold hardiness | About 5 °C (41 °F) once established (roughly USDA zone 11) |
| Heat stress | Likely above about 35 °C (95 °F) |
| Wind tolerance | None |
| Pollinator value | None |
| Edible | Not grown as food |
| Native to | Asia and tropical Africa |
| Common in gardens of | 🇨🇳 China, 🇻🇳 Vietnam, 🇮🇳 India, 🇹🇭 Thailand, 🇵🇭 Philippines, 🇮🇩 Indonesia |
Is Azolla (water fern) toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Fed to ducks, fish and pigs in Asia.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Azolla (water fern)
No well-documented helpful pairing. Group it with plants that like part sun to part shade and high water.
Questions about Azolla (water fern)
- How far apart should I plant Azolla (water fern)?
- About 5 cm (2 in) apart, centre to centre. A mature plant spreads 2–5 cm (1–2 in).
- Does Azolla (water fern) need full sun?
- Part sun to part shade: at least 4 hours of direct sun a day.
- How much water does Azolla (water fern) need?
- High water. Drought tolerance is none and waterlogging tolerance high.
- How cold-hardy is Azolla (water fern)?
- It tolerates about 5 °C (41 °F) once established, roughly USDA zone 11.
- Is Azolla (water fern) poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. Fed to ducks, fish and pigs in Asia.
- What grows well with Azolla (water fern)?
- There is no well-documented companion pairing for Azolla (water fern). Group it with plants that like the same sun (part sun to part shade) and water (high).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- Rice Knowledge Bank, International Rice Research Institute (IRRI)
- CABI Invasive Species Compendium, CABI
Notes and assumptions
- A floating fern that carries nitrogen-fixing cyanobacteria; grown in rice paddies. Keep it out of natural waters: it can choke them.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
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