How to Grow Robinia — Locust

Spring flowers. white flowers of Black Locust (Robinia pseudoacacia)

Robinia is fast-growing and well adapted to dry, hot regions. It produces hanging clusters of white or pink sweetpea-like flowers. The leaves are delicate and feathery, made up of numerous small leaflets borne on slender branches.

Robinia tolerates drought and urban conditions but its wood is brittle and susceptible to breaking in high winds. As well, the tender branches can be thorny.

Shrub members of the Robinia genus are suite for shrub borders.

Robinia pseudoacacia tree form

Get to Know Robina

  • Plant type: Deciduous shrubs or trees
  • Growing zones and range: Zones 4 to 9
  • Hardiness: Leaves drop with autumn frost
  • Height and width: Trees can grow to 60 feet (19m) tall and just as wide.
  • Foliage: Leaves divided like feathers into many roundish leaflets.
  • Flowers: Clusters of sweet pea-shaped white, or pink flowers
  • Bloom time: Mid-spring to early summer
  • Uses: Landscape tree; wood is brittle and may not be best suited for street planting
  • Common name: Locust
  • Botanical name: Robinia
  • Family name: Fabaceae
  • Origin: North America
Foliage and flowers of Robinia x ambigua
Foliage and flowers of Robinia x ambigua

Where to Plant Robinia

  • Plant Robinia in full sun.
  • Robinia grows best in humus-rich, well-drained soil but adapts to poor soil.

When to Plant Robinia

  • Set container-grown Robinia in the garden in spring or autumn.

Planting and Spacing Robinia

  • Space Robina 50 to 60 feet (15-18m) apart.
Flowers and leaves of Robinia viscosa
Flowers and leaves of Robinia viscosa

How to Water and Feed Robinia

  • Keep the soil evenly moist; established trees are drought tolerant.
  • Fertilize Robinia with an all-purpose, organic fertilizer in spring.

Robinia Care

  • Prune Robinia in fall or winter to develop a single leader; multiple trunks are weak.

Robinia Problems

  • Robinia wood is brittle; the roots are aggressive and plants often spread by suckers.
  • Suckers can sprout at a great distance from the trunk; they should be cut right away.
  • Robinia has shallow roots can be toppled by high winds, especially if the ground is soggy.

Robinia Propagation

  • Sow seed of species in spring.
  • Cultivars need to be grafted.
  • Suckers can be transplanted.
Purple robe locust tree. Latin name is Robinia pseudoacacia.
Purple robe locust tree. Latin name is Robinia pseudoacacia.

Robinia Varieties to Grow

  • Robinia ambigua: Hybrids between R. pseudocacia and R. viscosa; best-known varieties are ‘Decaisneana’ grows to 50 feet(15m) tall and 20 feet (6m) wide, ‘Idahoensis’ grows to 40 feet tall with magenta rose flowers, ‘Purple Robe’ similar to Idahoensis with darker purple-pink flowers.
  • R. hispida, rose acacia: Rounded shrub to 3 feet (.9m) tall with small pink flowers in spring.
  • R. x margaretta: Shrub or small tree grows to 13 feet (4m) tall
  • R. pseudoacacia, black locust: Grows to 75 feet (22m) with open branching; thorny branchlets; divided leaflets; fragrant white flowers in dense hanging clusters; varieties include ‘Frisia’, ‘Pyramidalis’, ‘Tortuosa’, and ‘Umbraculifera.’

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