Phormiums – Learn, buy & grow

This small genus includes just two species, P. tenax and P. cookianum, the latter split into two sub species, hookeri and cookianum.

Many hybrids have arisen from these species, making phormiums a very widely cultivated plant in New Zealand and the rest of the world, much loved for its hardiness and very architectural habit. There is now an amazing array of superb cultivars that have attractive or variegated foliage and much smaller leaves, making them more useable in smaller gardens; in fact there are some small forms that grow only up to 30cm high!

BUY: Phormiums here from UK Sellers

Phormiums are large and colourful ground-level plants grown for their spiky foliage that creates a dramatic and arresting focal point in your garden and landscape. These evergreen perennial plants are available in several cultivars with bright coloured blade-like leaves that shoot up directly from the base of the plant. They occur naturally in different sizes some growing as high as 7 feet while others are smaller and can be grown in pots indoors or around the garden.

READ MORE: Read more about how hardy are phormiums, or the best ways for cutting back phormium or a how to look after phormium plants

At maturity, the plant blooms phormium flowers that are yellow or red on flower stalks that shoot up from the base of the plant and extends higher than the leaves. After the bloom, attractive seed pods are produced for reproduction but if you do not have the intention of self-seeding, you can cut them off.

Phormium Varieties

Large Phormiums

Most of the listed Phormiums grow to be large and wide in just a few years, they are such great value plants that look striking and healthy all year round. The standard Phormium Tenax grows large pretty quickly too!

Where to buy Phormiums in the UK?

Phormium Tenax ‘New Zealand Flax’

An ornamental evergreen perennial with blade-shaped leaves as long as 10 feet. Its leaves range from bronze to green and sometimes occurs as a shade of chocolate brown with some cultivars producing variegated leaves with stripes or leaves with pink, orange, purple, or red edges. Phormium Tenax, also known as New Zealand flax thanks to its nativity is particularly grown for its bold foliage. It is an easy plant to care for and can survive in poor soil conditions. Generally, phormium tenax is an architectural plant great for borders, beds, coastal gardens, gravel gardens, etc.

Growing And Caring For Phormium Plants

Propagating Phormium

Phormium can be propagated by seed and by division. Planting and propagation by division is the simpler and more common method.

Propagation by division: Division is best done in late spring and for adequate growth, you can start a phormium plant as a plant pot indoors before replanting outdoors. Simply divide the leaf fans with rhizome and roots and replant them in a pot and store them in a warm place indoors.


Caring for phormium

Soil: This plant is not selective of soil type and will grow regardless of the quality of the soil as long as the soil is well-draining and slightly acidic to neutral.

Water: Phormium have average water needs and the soil should be kept consistently moist but do not overwater to avoid getting the roots soggy.

Light: Also not selective of light needs, phormium can do well in both full sun exposure and partial shade. Although in hotter climates, the afternoon sun is thought to enhance the foliage.

Temperature and humidity: Phormiums like warmth and humidity and will quickly wither when exposed to frost.

Fertilisers: They do not require feeding but are greedy feeders and will grow quickly when given a regular supply of fertiliser. Ideally, compost added to the topsoil will retain moisture and supply the plant with nutrients.

Pruning: Pruning is not needed but when it is done it should be in a diagonal shape to maintain the beauty of the foliage.


Phormium Colensoi ‘Mountain Flax’

Phormium colensoi, also called mountain flax or coastal flax is a less common phormium species and is also endemic to New Zealand. It is an evergreen perennial and occurs smaller than its counterpart species New Zealand flax. Its leaves are less than 6 feet in length and rise to just about the same length. It blooms tepals that are yellow to red outward and green inner tepals. It is cultivated less as an ornamental plant but used instead for weaving.

Cultivars of New Zealand Flax

Phormium Sundowner

This is a slow-growing evergreen perennial that forms a clump of erect blade-shaped leaves that grow to a length of 3 feet and sometimes more. Its leaves are variegated with red and pink stripes and it sparingly blooms yellow flowers. Just like other species of phormium tenax, it can grow in poor soil conditions as long as the soil is well-draining and slightly acidic to normal. 

Phormium Jester: Also a clump-forming evergreen perennial with variegated pink leaves with green stripes. It sparingly produces red flowers in summer on leafless stalks that shoot up higher than the leaves. It has a slightly weeping habit and doesn’t grow upwards with leaves about 4 feet in length. Additionally, it survives in poor soil conditions, full sun, and can be grown indoors.

Phormium 'evening glow'
Read more about the Phormium evening glow here

Phormium Yellow Wave: A clump-forming ornamental evergreen plant that adds a burst of colour to your garden all year round. Its leaves are slightly different from other cultivars and appear in a cascading strap-shaped with lengths of 3 inches. In summer, a flowering stalk carrying pannicles of yellow flowers shoot up above the leaves and create a dramatic scene. This is grown particularly for its brightly coloured foliage and make a beautiful scene at borders, coastal gardens, gravel gardens, city gardens, etc.

Other popular cultivars are phormium yellow wave and phormium bronze baby which produce flowers that create a phormium cream delight.


When do you divide phormium?

The best time to divide phormiums for propagation is in spring. Simply divide the leaf fans with roots and replant them.

Are phormium plants poisonous to dogs?

Phormiums are poisonous for some animals and are also considered one of the most bitter tastes for human consumption.

When do phormiums flower?

The yellow, green, red, or brown flowers of phormium plants are usually produced in summer.

What can you plant with phormium?

You can add structure to your garden by planting trees of different sizes as well as shrubs. To project the beauty of phormiums, it is best to plant them with ornamental grasses, and other colourful perennials to create a mixture of long and short grasses. 

How do you cut back phormium?

Cutting back phormium requires a bit of care. Cut in a diagonal shape so as not to hurt the beauty of the plant. The best time to prune phormium is in autumn just before you begin preparing the plant for winter. More: Can phormiums can be cut back?

Will phormium grow in shade?

Phormiums are relatively easy to grow and will grow in shade and full exposure. They are tolerant of both shaded areas and sunny areas, though they particularly like exposure to the sun. More: How to look after a phormium

Are phormiums hardy?

Phormiums are not all completely hardy and can be damaged by frost. The standard phormiums will make it through the winter though! Plant your phormiums in spring so that they can be completely developed and established before the winter. Planting in later seasons like summer and autumn is also possible but your plants will be more prone to frost damage. Read more about whether phormiums are hardy here