New Zealand flax grass (Phormium): planting and care

Updated on 22 September 2026Published on 20 July 2023

Long, upright leaves fan out in shades of purple, bronze and green, sometimes striped, forming a clump that can reach 6.5 feet (2 meters). New Zealand flax (Phormium) earns its keep as a bold bushy perennial for terrace pots and garden edges, but it is barely hardy: give it well-drained soil and shelter from frost, and the colour lasts all year.

New Zealand flax at a glance
Name	Phormium
Family	Agavaceae
Type	perennial
Height	6.5 feet (2 meters)
Exposure	sunny
Soil	well-drained
Foliage	evergreen
Bloom	early summer to late summer

Planting New Zealand flax

Ideal spot for planting New Zealand flax? A sunny one. Plant it in spring. Perfect for a terrace pot, it also does wonders as a garden edge. Its low hardiness implies it might struggle with negative temperatures (coldest 21°F or -6°C). Pot cultivation and a cozy winter shelter would do it good.

Container planting? All you need is potting soil.
In-ground planting? Mix potting soil + garden soil.
Regardless, soil needs to be well-drained.
Propagation through division after blooming come fall.

Caring for New Zealand flax

New Zealand flax in a pot — Pots can be moved to frost-free shelter

After blooming, chop flower stems back very short.

Remove leaves only when they’ve withered away.
Give the plant base some winter protection with a healthy mulch of dried leaves.
If in a pot, bring it in it away from frost, but not in a heated room.

Watering New Zealand flax:

Wait till soil dries out well between waterings, especially for pots and containers. In the open ground, quench its thirst with abundant water when it’s hot, particularly during the first two years.

Learn more about New Zealand flax

Uses of New Zealand flax — Maori wove the leaves into baskets and clothing

Boasting a splendid clump, New Zealand flax makes a stunning bushy perennial, adapting especially well to potted growing on your terrace or balcony, particularly if winters are cold. Depending on the variety, foliage comes in shades of purple, bronze, green, and sometimes striped. True to its name, this plant hails from New Zealand.

You’ll find it a lot in bushy and marshy areas of New Zealand. New Zealand Flax got highly utilized (and still is) by Maori for various uses like making baskets or clothing. Even its roots have disinfectant properties.

Smart tip about New Zealand flax

A mineral mulch brings out beauty in this colorful perennial.

Frequently Asked Questions

Is New Zealand flax hardy enough to leave outdoors in winter?

Only in mild gardens. Its hardiness is low and it may struggle once temperatures drop below freezing, with about 21°F (-6°C) given as the limit. Where winters are colder, grow it in a pot and move it to a frost-free shelter, and mulch the base of in-ground plants with dried leaves.

Can New Zealand flax be grown in a pot on a terrace or balcony?

Yes, and it is one of the best ways to grow it where winters are cold. For a container, plain potting soil is all you need, provided it drains freely. Bring the pot under cover away from frost in winter, but do not stand it in a heated room.

How often should I water New Zealand flax?

Let the soil dry out well between waterings, which matters most in pots and containers where drainage is limited. Plants in the open ground should be watered generously in hot weather, especially during their first two years while the clump is establishing.

What should I cut back, and when?

The plant flowers from early summer to late summer, and once flowering is over the flower stems are cut back very short. Leaves are left alone until they have withered completely, then removed. Division of the clump is done after flowering, in autumn.

Images: CC BY 2.0: K M, K M, CC BY-SA 2.0: Megan Hansen; Public Domain: Bernard Spragg

Written by Gaspard Lorthiois | Loves helping out, especially when it comes to growing things. Worked in herbal medicine, runs a farm, and dabbles in tech. Master's degree and engineer.

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