Description

General aspect and origins - Phormium cookianum is also known as Mountain Flax, or sometimes Wharariki. It is a perenial plant which is native to New Zealand, and that naturalized in mild coastal zones like the Scilly Islands. (UK) This plant has long evergreen and drooping leaves.
Leaves - Phormium cookianum has long drooping evergreen leaves that can be up to 6 ft (2 m) long. The species has green leaves, but there are also varieties and forms that have variegated leaves. For instance :

Phormium cookianum ssp. hookeri 'Cream Delight' has green leaves with yellow-cream stripes.

Phormium cookianum ssp hookeri 'Tricolor' which has green leaves with red and yellow edges.

Phormium cookianum 'Variegatum' with variegated leaves.
Flowers - Flowers are yellow-green, with prominent scarlet stamens. Moreover, Phormium cookianum has hermaphrodite flowers.

Culture

Phormium cookianum is a plant which is adapted to coastal conditions, and which can withstand negative temperatures down to about 15°F (-9°C to -10°C). This plant can thus be grown in USDA zones 8b and warmer.
Soil - This Phormium can grow in a relatively large range of soils, but prefers a well drained ground.

Propagation

This Phormium is generally propagated by seeds, or by division of the plant in spring.