Perennial

New Zealand Flax

Phormium tenax

Large evergreen fans of sword-shaped leaves provide bold year-round structure.

  • Full sun, Partial shade
  • 2.5–4 m (8–13 ft)
  • 1.5–2.5 m (5–8 ft)
  • H5
  • July–August
  • Evergreen

Overview

A robust species flax for spacious borders and coastal schemes. Choose fertile well-drained ground and allow room for its broad clump. Flower stems can reach around 4m but flowering is not guaranteed every year. Protect young plants and containers during severe northern winters. Source: https://www.rhs.org.uk/plants/12791/phormium-tenax/details

At a Glance

Sun Full sun, Partial shade
Height 2.5–4 m (8–13 ft)
Spread 1.5–2.5 m (5–8 ft)
Hardiness H5
Flowers July–August
Soil Loam, Sand
Moisture Moist well drained
Habit Clump forming
Water Moderate
Maintenance Easy

Growing Conditions

Min. Temperature -15°C (5°F)
Fertility Fertile
Drainage Free Draining

Aspect Suitability

  • North-facing
  • East-facing
  • South-facing
  • West-facing

Site Tolerance

  • Exposed sites
  • Wind
  • Coastal

Soil Tolerance

  • Sandy
  • Loam
  • Acid
  • Neutral pH
  • Alkaline

Foliage

Persistence Evergreen
Colour Green, Grey-green
Leaf shape / texture Sword-shaped
  • Architectural foliage

Foliage interest: 12 months of the year

Seasonal Timeline

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Flowering
Foliage
Propagate
  • Flowering Jul Aug
  • Foliage 12 months of the year
  • Propagate Apr May

Maintenance Calendar

  • Apr Cut damaged outer leaves at the base without shearing the clump
  • Apr Divide overgrown clumps if required
  • Jun Check leaf bases for mealybugs
  • Nov Insulate pots and protect young plants during severe cold

Garden Design

Works well in: Coastal, Contemporary, Tropical

Use upright leaves to contrast with rounded foliage. Height includes flower stems; the species needs a very large container. Ratings for wildlife, tropical appearance and architecture are editorial estimates on a 1-5 scale. Spacing and care months are UK planning guides; adjust to local conditions.

Companion planting: Palms, Grasses, Rounded shrubs

Wildlife Value

  • Shelter

Safety

Tough leaves have pointed tips; keep clear of eye level along narrow paths and wear gloves when dividing. Blank toxicity flags mean unverified, not confirmed safe.