Phormium tenax 'All Black'

RHS Plant Profile

New Zealand flax 'All Black'

RHS / Joanna Kossak

Synonyms

Phormium 'All Black'

Shrubs

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A tough and robust evergreen perennial to 2m tall, with upright and arching, sword-shaped, dark purple leaves. In summer mature plants may produce a tall flowerspike bearing tubular red flowers

Position

Full sun, Partial shade

Soil Types

Chalk, Loam, Sand

Max Height

1.5-2.5 metres

Max Spread

1-1.5 metres

Size

Time to Maturity: 5–10 years
Max Spread: 1-1.5 metres
Max Height: 1.5-2.5 metres

Growing Conditions

Chalk Loam Sand

Moisture: Moist but well–drained or Well–drained
pH: Acid or Alkaline or Neutral

Position

Full sun Partial shade

Aspect: East–facing or South–facing or West–facing
Exposure: Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H5
Drought Resistance: Yes

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Asphodelaceae
Native to GB/Ireland: No
Foliage: Evergreen
Habit: Clump forming
Genus: Phormium are evergreen perennials, making a large clump of leathery, strap-shaped leaves, with tall panicles of small, tubular flowers in summer
Name Status: Accepted

How to Grow

Cultivation

Grow in fertile, moist but well-drained soil in full sun or partial shade. Established plants are drought-resistant. See Phormium cultivation

Propagation

Propagate by division in spring

Suggested planting locations and garden types

Architectural
Coastal
Gravel garden
Sub-tropical
Low Maintenance
Flower borders and beds

Pruning

No pruning required

Pests

May be susceptible to phormium mealybug

Diseases

May be susceptible to honey fungus (rarely)