Vernonia baldwinii

RHS Plant Profile
western ironweed

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Herbaceous Perennial
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A clump-forming, rhizomatous perennial to 1.5m tall bearing flattened flower heads up to 30cm in diameter made up of 15-30 tiny purple flowers borne on stout, hairy stems from summer into autumn. The lance-shaped, deep green leaves have serrated margins and reach up to 17cm in length.

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

1-1.5 metres

Max Spread

0.5-1 metres

Size

Time to Maturity
2–5 years
Max Spread
0.5-1 metres
Max Height
1-1.5 metres

Growing Conditions

Chalk Clay Loam Sand
Moisture
Moist but well–drained or Well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun Partial shade
Aspect
South–facing or West–facing or East–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)
H7

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Asteraceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming, Columnar upright
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
C & S USA

How to Grow

Cultivation

Grow in a moist, light soil in full sun or partial shade

Propagation

Propagate by seed or division

Suggested planting locations and garden types

  • Cottage and informal garden
  • Prairie planting
  • Cut flowers
  • Flower borders and beds

Pruning

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

Pests

Generally pest-free

Diseases

Generally disease-free