Growing the Spiky, Spectacular New Zealand Flax (Phormium)

Green Variegated Phormium
© Marie Iannotti

Overview and Description of New Zealand Flax

Gardeners grow New Zealand Flax as a large and often colorful, spiky plant that makes an arresting focal point in the garden or in containers. It has sword-like leaves that shoot up from the base of the plant and new hybrids are now available in bright shades of yellow, pink, red and bronze.

These sword-leafed, evergreen perennials are often used as specimen plants.

Some are small enough to use in containers, others can reach several feet in diameter and over 7 feet tall.

On mature plants, the flower stalks shoot up above the leaves and produce curving, tubular red or yellow blossoms that are very high in nectar and a hummingbird favorite. Seed pods form after the flowers bloom. The seed pods are attractive in their own right, but deadhead, if self-seeding is not desired.

Phormium got the name New Zealand Flax because the Maoris of New Zealand actually used it for making a type of linen clothing, as well as for ropes and baskets.

Botanical Name

Phormium tenax and Phormium cookianum

Common Name

New Zealand Flax

USDA Hardiness Zone

Although you see New Zealand Flax for sale everywhere, it is only perennial in  USDA Hardiness Zones 8 - 10 and will need some protection during tough winters in Zone 8. However, the rest of us can easily grow New Zealand Flax as an annual plant and enjoy it outdoors throughout the summer.

You can also bring it indoors for the winter, as a houseplant.

Mature Size

The mature size of your New Zealand Flax plant will depend on the variety and your growing conditions. Many plants in containers grow 1 to 4 ft. tall. Phormium tenax, the taller of the 2 species, can reach 10 feet under ideal conditions.

Most New Zealand Flax plants average out between 2 and 5 ft.

Exposure

Full sun to partial shade. Since you are growing your New Zealand Flax for its foliage, not its flowers, full sun is not crucial. In fact, in hotter climates, your plant may do better with a little afternoon shade.

Bloom Period

New Zealand Flax does send up a nice flower stalk with red or yellow flowers in mid-summer, but it is predominately grown for its foliage.

New Zealand Flax Growing Tips

New Zealand Flax prefers a rich, moist soil and a location sheltered from harsh winds, but once established, the plants really aren’t fussy about conditions.

Phormium can easily be grown in containers. Choose a rich, organic mix over a traditional potting soil and keep the plants well-watered in summer’s heat. Don’t allow the plants to experience frost. New Zealand Flax can be grown indoors, either as a house plant or under lights. It prefers cool temperatures in winter, but lots of sunlight.

Maintenance: Divide plants in the spring. You can start new plants indoors by potting larger rhizome pieces and allowing them to grow a bit before relocating outdoors.

New Zealand Flax can also be started from seed, although it needs a warm temperature of over 60 degrees F to germinate.

Design Tips

Use New Zealand Flax in place of Dracena or spiky Vinca in containers and in place of grasses in garden beds. Contrast Phormium's dramatic leaves with low-growing, delicate foliage, such as perennial geraniums and coreopsis. New Zealand Flax can even be grown successfully in bog areas.

The leaves can also be cut in the fall, for use in flower arrangements.

Suggested Varieties

New varieties are introduced just about every year and they get more and more ornamental. Take a look around your local nursery at what they've come up with this year. Here are a handful of old favorites.

  • Phormium ‘Bronze Baby’ - Bronze foliage. Grows to about 2 ft. tall and 2-3 ft. wide. Good for containers.
  • Phormium ‘Duet’ - Dwarf (approx. 1 ft.). Green leaves edged in cream. Very stiff leaf blades.
  • Phormium ‘Jester’ - Bronze with green stripping. About 3 ft. tall.
  • Phormium ‘Sundowner’ - Green leaves with rosy-pink margins. About 6 ft. tall and wide.

Problems & Pests

Mealy bugs can infest plants and are hard to eradicate from inside the long leaves. Many times it’s easiest to just dispose of the infested plant.