How to Grow Phormium – New Zealand Flax 

Phormium, New Zealand flax
New Zealand flax, Phormium

Phormium – commonly called New Zealand flax –is a dramatic plant composed of sword-like, stiffly vertical leaves in a fan pattern. Cultivars often range in colors from yellow-green to dark green with white or yellow stripes.

Phormium bears tall erect panicles of 1 to 2-inch (5cm) tubular blossoms in dull red or yellow. Flowers appear in late summer and autumn.

Use Phormium as an accent plant in a border, lawn, or near a building. Phormium is sturdy and fast-growing. Phormium can tolerate salt air and ocean spray. It can be easily grown as a container plant.

Phormium is a genus of two species of evergreen perennials native to scrub and swamps and hillsides near riverbanks in New Zealand.

Variegated Phormium
Variegated Phormium

Get to Know Phormium 

  • Plant type: Evergreen perennial 
  • Growing zones and range: Zones 9 and 10 
  • Hardiness: Generally Zone 9 south 
  • Height and width: 5 to 7 feet (1.5-2m) tall and 4 feet wide (1.2m) 
  • Growth rate: Fast 
  • Form and habit: Clump-forming 
  • Foliage: Large, linear, keeled leaves, each folded into a V-shape at the base, and ranging in color from yellow-green to dark green, with many fine stripes 
  • Flowers: Abundant small, 1-2 inch (2.5-5cm), tubular 6-petaled, dull red or yellow flowers are produced in erect panicles on leafless stems 
  • Bloom time: Summer 
  • Uses: Border, by a building, at the edge of a lawn, coastal garden, accent plants, near swimming pools, specimen 
  • Common name: New Zealand flax 
  • Botanical name: Phormium 
  • Family name: Agavaceae 
  • Origin: New Zealand 

Where to Plant Phormium 

  • Plant Phormium in full sun. 
  • Plant Phormium in fertile, moist but well-drained soil. 
  • Where marginally hardy, provide a deep, dry mulch in winter. 
  • Phormium tolerate salt air and ocean spray, but not dune conditions. 
  • In areas where they are marginally hardy, select a sheltered, south-facing site and protect plants with a thick layer of dry mulch such as salt hay or weed-free straw over winter.  

When to Plant Phormium 

  • Sow Phormium seed at 55-64°F (13-18°C) in spring. 
  • Set container-grown Phormium in the garden in spring or autumn.
New Zealand Flax, red striped Sundowner variety
New Zealand Flax, red striped Sundowner variety

Planting and Spacing Phormium 

  • Space Phormium 6 to 10 feet (2-3m) apart.

How to Water and Feed Phormium 

  • Give Phormium much or little water. 
  • Feed Phormium with an all-purpose organic fertilizer in spring. 

How to Care for Phormium 

  • Where Phormium is marginally hardy, place a deep, dry mulch over the crown in winter or overwinter the plant indoors.

Phormium Pests and Diseases 

  • Phormium can sometimes develop leaf spots or crown rot. 
Flowering New Zealand Flax, Phormium tenax
Flowering New Zealand Flax, Phormium tenax

Phormium Propagation 

  • Divide Phormium clumps in spring. 
  • Sow seed in warming soil or in a warming cold frame in spring.

Phormium Varieties to Grow 

  • Phormium cookianum, Mountain flax, clump-forming perennial ith broad, arching, linear, light to yellowish green leaves, to 5 feet (1.5m) long. Tubular, yellow-green flowers, to 1.5 feet (4cm) long, are produced in upright panicles, 6 feet (2m) long, in summer. To 6 feet (2m) tall and 10 feet (3m) wide. New Zealand. 
  • P. tenax, New Zealand flax, clump-forming perennial with rigid, upright, linear leaves, to 10 feet (3m) long, dark green above, blue-green beneath. Thick, red-purple panicles, to 12 feet (4m) long, of tubular, dull red flowers, 2 inches (5cm) long, are borne in summer. To 12 feet (4m) tall and 6 feet (2m) wide. New Zealand.    

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