HARDINESS: Zones 8 to 10
PREFERRED SOIL pH: Neutral
PREFERRED SOIL TYPE: Fertile, moist, well-drained
PREFERRED LIGHT: Sun to partial shade
ATTRIBUTES: Straplike evergreen foliage in various colors; for beds, pots
SEASON OF INTEREST: Year-round if kept from freezing
FAVORITES: P. tenax 'Bronze Baby', 'Cream Delight'; P. colensoi 'Sundowner', 'Maori Maiden'
QUIRKS: Not frost tolerant but can be Wintered indoors
GOOD NEIGHBORS: Flowering annuals, perennials, small evergreen shrubs
WHERE IT GROWS BEST: In sun and well-drained soil in areas with mild winter temperatures
POTENTIAL PROBLEMS: Damage from freezing winter weather or high summer temperatures
RENEWING PLANTS: Lives years; divide when crowded, or shift potted plants to larger pots
CRITTER RESISTANCE: Good
SOURCE: Bedding plants, division
DIMENSIONS: 3-15 ft (1-4.6 m) tall, 2-3 ft (0.6-1 m) wide
Phormium in the Landscape
Tough and colorful, phormium is a foliage plant with architectural qualities ideal for use in containers or as a featured plant in beds. Also called New Zealand flax, this plant produces long, straplike foliage. The leaves can be stiffly upright and spiky, slightly arched, or curved and weeping, depending on the species and cultivar. In color they may be a solid glossy green or purple, or they may be a brilliantly multicolored combination of several shades of green, purple, bronze, pink, red, cranberry, peach, cream, or yellow.
Smaller garden phormiums measure 3 ft (1 m) high and wide, but Phormium tenax can reach heights of 15 ft (4.6 m) when blooming. Its stalks rise from a gigantic irislike clump, with leaves up to 6 ft (1.8 m) long and 2 in (5.1 cm) wide.The brownish red flowers, more interesting than beautiful, attract hummingbirds.
Phormium is not reliably frost hardy, so gardeners in cold-winter areas either buy new plants every year or protect them by bringing them indoors for the winter. Although phormium tolerates wind quite well, it prefers cool summers, making it a great plant for coastal California and areas with a similar climate.
Calling All Phormium Fanatics
Phormiums with varied leaf colors and shapes have been bred for gardens. One good cultivar of P. tenax is called 'Bronze Baby', which has narrow copper-purple leaves and a 3 ft (1 m) height. Mountain flax (P. colensoi) has given gardeners 'Cream Delight', a weeping form with green leaf margins surrounding a broad cream central band; 'Maori Maiden", featuring coral-striped bronze leaves; and 'Sundowner', which has leaves in purple, cream, and pink.
Set plants in full sun to partial shade. Although they thrive in moist soil, good soil drainage is essential. In heavy clay soils, plant phormiums on a slope to help direct water away from the roots. In hot-summer areas, plant in a shady or partly shaded spot to keep leaves from being sunburned. Keep plants watered during extended droughts and protect them from frost in areas where they are marginally hardy. Otherwise, this plant is undemanding and extraordinarily pest and disease free.
Increasing the Bounty
If happy with its location, phormium will spread into a big clump. But it forms a strong root system that takes muscle power to divide. To nip off a division, cut the leaves of a small side section nearly down to the ground, leaving leaves on the other side of the clump. With a sharp knife, cut off a rooted plantlet, without disturbing the roots or leaves of the rest of the clump. When replanting, set the plant-let at the same depth as the parent clump, and keep the soil moist until the division is rooted and growing.
Phormium also can be started from seed. Seeds germinate best after cold, moist treatment. Wrap the seeds in damp paper towels, put the towels inside a plastic bag, and refrigerate them for 6 weeks. Then plant in sterile commercial seed-starting medium, covering seeds with 1/2 in (1.3 cm) of medium. Keep the soil at room temperature and moist until germination occurs. Move the seedlings to a sunny location, keep the soil moist, and plant the young plants in pots before the roots become crowded.