New Zealand flax Phormium tenax
New Zealand flax (Phormium tenax) is an evergreen perennial grass in the Asphodelaceae family, native to New Zealand and Norfolk Island. It grows 1.2–2.5 m (3.9–8.2 ft) tall and 1–2 m (3.3–6.6 ft) wide, wants full sun and moderate water, and is hardy to about -10 °C (14 °F). Space plants about 1.5 m (4.9 ft) apart.
Plan New Zealand flax in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
New Zealand flax at a glance
| Type | Perennial grass, evergreen |
|---|---|
| Family | Asphodelaceae |
| Mature height | 1.2–2.5 m (3.9–8.2 ft) |
| Mature spread | 1–2 m (3.3–6.6 ft) |
| Spacing | 1.5 m (4.9 ft) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance moderate, waterlogging tolerance moderate |
| Soil pH | 5.5–7.5 |
| Cold hardiness | About -10 °C (14 °F) once established (roughly USDA zone 8) |
| Heat stress | Likely above about 35 °C (95 °F) |
| Flowering | from about July for 4–9 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | High |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | New Zealand and Norfolk Island |
| Common in gardens of | 🇬🇧 United Kingdom, 🇦🇺 Australia, 🇳🇿 New Zealand |
| Invasive in | St Helena and other oceanic islands (CABI ISC), Australia (environmental weed in parts of southern states and island territories): check local rules before planting |
Is New Zealand flax toxic?
- People: not well documented
- Cats: not well documented
- Dogs: not well documented
No toxicity documented in ASPCA or standard poison references; treat as untested.
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 New Zealand flax
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
See New Zealand flax in a botanical garden
It grows in these sample gardens, which you can walk through in 3D:
- UC Botanical Garden, Berkeley (4 plants)
- The Butchart Gardens (3 plants)
- Kew: glasshouses and rock garden (2 plants)
Questions about New Zealand flax
- How far apart should I plant New Zealand flax?
- About 1.5 m (4.9 ft) apart, centre to centre. A mature plant spreads 1–2 m (3.3–6.6 ft).
- Does New Zealand flax need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does New Zealand flax need?
- Moderate water. Drought tolerance is moderate and waterlogging tolerance moderate.
- How cold-hardy is New Zealand flax?
- It tolerates about -10 °C (14 °F) once established, roughly USDA zone 8.
- When does New Zealand flax flower?
- From about July for 4–9 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is New Zealand flax poisonous to cats and dogs?
- For cats it is not well documented; for dogs not well documented; for people not well documented. No toxicity documented in ASPCA or standard poison references; treat as untested.
- What grows well with New Zealand flax?
- There is no well-documented companion pairing for New Zealand flax. Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade C (C: plausible, mixed evidence).
- RHS Plant Finder, Royal Horticultural Society
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- CABI Invasive Species Compendium, CABI
Notes and assumptions
- Cultivars with bronze, purple or striped leaves are usually smaller (0.6 to 1.5 m) and less hardy than the green species.
- Flowers are rare in cool climates.
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
- Daylily Hemerocallis fulva
- Red hot poker Kniphofia uvaria
- Aloe vera Aloe vera
- Quiver tree (kokerboom) Aloidendron dichotomum
- Bitter aloe (Cape aloe) Aloe ferox
- Grass tree (balga) Xanthorrhoea preissii
- Blue flax lily (paroo lily) Dianella caerulea
- Krantz aloe (candelabra aloe) Aloe arborescens