Silver tree fern (ponga) Alsophila dealbata
Silver tree fern (ponga) (Alsophila dealbata) is an evergreen perennial tree in the Cyatheaceae family, native to New Zealand (forest understorey). It grows 4–10 m (13–33 ft) tall and 3–5 m (10–16 ft) wide, wants part sun to part shade and high water, and is hardy to about -3 °C (27 °F). Space plants about 3 m (10 ft) apart.
Plan Silver tree fern (ponga) in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Silver tree fern (ponga) at a glance
| Type | Perennial tree, evergreen |
|---|---|
| Family | Cyatheaceae |
| Mature height | 4–10 m (13–33 ft) |
| Mature spread | 3–5 m (10–16 ft) |
| Spacing | 3 m (10 ft) centre to centre |
| Sun | Part sun to part shade, at least 3 h of direct sun a day |
| Water | High; drought tolerance none, waterlogging tolerance low |
| Soil pH | 5–6.5 |
| Cold hardiness | About -3 °C (27 °F) once established (roughly USDA zone 9) |
| Heat stress | Likely above about 30 °C (86 °F) |
| Wind tolerance | Low |
| Pollinator value | None |
| Edible | Not grown as food |
| Native to | New Zealand (forest understorey) |
| Common in gardens of | 🇬🇧 United Kingdom, 🇦🇺 Australia, 🇳🇿 New Zealand |
Is Silver tree fern (ponga) toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
No toxicity reported in ASPCA or standard poison references.
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 Silver tree fern (ponga)
No well-documented helpful pairing. Group it with plants that like part sun to part shade and high water.
See Silver tree fern (ponga) in a botanical garden
It grows in these sample gardens, which you can walk through in 3D:
- The Huntington (1 plants)
- UC Botanical Garden, Berkeley (1 plants)
- Kew: glasshouses and rock garden (1 plants)
Questions about Silver tree fern (ponga)
- How far apart should I plant Silver tree fern (ponga)?
- About 3 m (10 ft) apart, centre to centre. A mature plant spreads 3–5 m (10–16 ft).
- Does Silver tree fern (ponga) need full sun?
- Part sun to part shade: at least 3 hours of direct sun a day.
- How much water does Silver tree fern (ponga) need?
- High water. Drought tolerance is none and waterlogging tolerance low.
- How cold-hardy is Silver tree fern (ponga)?
- It tolerates about -3 °C (27 °F) once established, roughly USDA zone 9.
- Is Silver tree fern (ponga) 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. No toxicity reported in ASPCA or standard poison references.
- What grows well with Silver tree fern (ponga)?
- There is no well-documented companion pairing for Silver tree fern (ponga). 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).
- New Zealand Plant Conservation Network: flora, NZPCN
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- RHS Plant Finder, Royal Horticultural Society
Notes and assumptions
- Frost-tender to half-hardy: in cold-winter climates it needs a cool glasshouse (as in the Kew Temperate House).
- Ferns do not flower; flowering values are placeholders.
- Silver-white frond undersides; the silver fern is a national emblem of New Zealand. Also known as Cyathea dealbata.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Malesian tree fern Alsophila contaminans
- Spiny tree fern Alsophila spinulosa
- Lacy tree fern (Cooper’s tree fern) Sphaeropteris cooperi
- Dwarf mountain pine Pinus mugo
- Japanese maple Acer palmatum
- Black walnut Juglans nigra
- English yew Taxus baccata
- Serviceberry Amelanchier canadensis