• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

Robinia pseudoacacia

false acacia

  • Other common names false acacia
    common robinia

    bastard acacia
    black locust
    fragrant white locust
    locust
    yellow locust

    see more
  • Family Fabaceae

  • Genus Robinia are vigorous suckering trees and shrubs, sometimes thorny, with pinnate leaves and racemes of pea-type flowers in early summer, sometimes followed by seed pods

  • Details R. pseudoacacia is a fast-growing, spreading tree to 25m tall with deeply furrowed rough bark and spines formed from stipules on twigs and suckers. The dark green leaves comprise 5-11 pairs of oval leaflets. Dense, drooping clusters of slightly scented white flowers, each 15-20mm long and with a yellow blotch at the base of the standard petal, are borne in late spring and summer and are followed in autumn by hairless, linear to oblong pods containing 4-10 seeds

  • Plant range Europe, N America

Characteristics

  • Foliage Deciduous

  • Habit Columnar/Upright

  • Fragrance Flower

  • Toxicity All parts may cause severe discomfort if ingested

  • 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)

    H6

Colour

Sunlight

  • Full Sun

  • Aspect South-facing or West-facing or North-facing or East-facing

  • Exposure Sheltered

Soil

  • Sand

    Sand

  • Clay

    Clay

  • Chalk

    Chalk

  • Loam

    Loam

  • MoistureWell-drained, Moist but well-drained

  • SoilSand, Clay, Chalk, Loam

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height Higher than 12 metres

  • Ultimate spread wider than 8 metres

  • Time to ultimate height 20-50 years

How to grow

Cultivation Grow in moderately fertile soil; will tolerate poor dry soils. Larger trees develop brittle branches which may be damaged or dropped in strong winds. Suckering may be a problem

Propagation Propagate by seed or from root cuttings or from suckers

Suggested planting locations and garden types Low Maintenance Drought Resistant

How to care

Pruning Pruning group 1 or Pruning group 7; pruning should be done in late summer or early autumn to prevent bleeding; sucker removal if necessary, in autumn

Pests Generally trouble free

Diseases Generally disease free but in more recent years there have been Frisia dieback problems

Did you find the information you were looking for?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.