Alternanthera dentata 'Purple Knight'

Synonyms

Alternanthera 'Purple Knight'

Conservatory Greenhouse Annual Biennial Herbaceous Perennial

A vigorous, spreading upright tender evergreen perennial grown as an annual for the dark purple stems and foliage. Leaves are lance shaped and flowers are occasional, white and insignificant, in summer.

Position

Full sun

Soil Types

Chalk, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 1–2 years
Max Spread: 0.1-0.5 metres
Max Height: 0.1-0.5 metres

Growing Conditions

Chalk Loam Sand

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

Position

Full sun

Aspect: South–facing
Exposure: 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): H1C

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Amaranthaceae
Native to GB/Ireland: No
Foliage: Evergreen
Habit: Bushy, Spreading branched, Columnar upright
Genus: Alternathera are bushy annuals and perennials with colourful leaves and insignificant flowers
Name Status: Accepted

How to Grow

Cultivation

Plant in light moist but well-drained fertile soil in sheltered sunny sites as an annual. Darkest leaf colour develops in full sun. Also grown under glass in light loam compost with plenty of light, water and regular feeding.

Propagation

Propagate by division, seed and stem tip cuttings

Suggested planting locations and garden types

City and courtyard gardens
Patio and container plants
Flower borders and beds
Ground cover
Garden edging

Pruning

Pinch out tips and clip back to keep bushy shape

Pests

May be susceptible to glasshouse red spider mite

Diseases

May be susceptible to fusarium wilt