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Herbaceous Perennial

Vernonia lettermannii

narrowleaf ironweed

A clump-forming perennial with upright, smooth, leafy stems to 80cm high. Leaves are narrow and threadlike, to 9cm long but only 1-3mm wide. In late summer, flattened clusters of 10-12 small violet flowers are produced on branched stems above the foliage. Flowers are followed by grey-brown seedheads

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Ultimate height

0.5–1 metres

Time to ultimate height

1–2 years

Ultimate spread

0.5–1 metres

Chalk

Clay

Loam

Sand

Moisture

Moist but well–drained, Well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

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)

Botanical details

Family: Asteraceae
Native to GB / Ireland: No
Foliage: Deciduous
Habit: Clump forming
Genus: Vernonia are annuals, perennials, climbers, sub-shrubs, shrubs and trees, though only the perennials are in cultivation. They have upright stems, simple, stalkless leaves and flat branched heads of tubular purple or reddish pink, occasionally white, flowers
Name status: Correct
Plant range: USA (Arkansas, Oklahoma)

How to grow

Cultivation

Grow in a light, moderately fertile, moist soil preferably in full sun but will tolerate partial shade

Propagation

Propagate by seed or by division; will self seed freely if not deadheaded

Suggested planting locations and garden types

Cottage and informal garden
Wildflower meadow
Banks and slopes
Flower borders and beds

Pruning

Deadhead to prolong flowering and, if necessary, to prevent self-seeding

Pests

Generally pest-free

Diseases

Generally disease-free

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