Black locust tree, false acacia

Black locust tree, which is also called false acacia, is a tree species considered invasive.

Black Locust facts, a summary

Name – Robinia pseudoacacia
Family – Fabaceae
Type – tree

Height – 30 to 50 feet (10 to 15 meters)
Exposure – full sun
Soil – ordinary

Foliage – deciduous
Flowering – June
Fruit formation – summer

Planting black locust tree

Plant preferably in fall to favor root development before winter and proper regrowth in spring.

If purchased in a container, you can also plant it in spring, taking great care to increase watering at the beginning.

  • Black locust tree loves full sun, that’s where it blooms best.
  • A mix of garden soil and planting soil mix is perfectly suited to grow it.

Pruning and caring for black locust tree, false acacia

No specific pruning is required, but it is important to remove dead or weak branches whenever you notice them.

  • Eliminating dead and diseased branches must be performed regularly.
  • In fall, prune branches that cross over each other and in-growing branches.
  • Snip off suckers in fall, they are quite useless to the tree.

It is also possible to restrict this tree’s growth by pruning it or removing larger branches in fall.

Learn more about black locust tree

Tall upright black locust treeBlack locust tree got its scientific name Robinia from its inventor or discoverer Jean Robin, the royal botanist of Henry the IVth of France who planted it for the 1st time Place Dauphine, in Paris, in 1601.

Native to the United States of America, false acacia, which also goes by the common name black locust tree, is a very elegant tree with a balanced bearing. Its hardiness leads it to live a very long life.

  • This fast-growing tree is particularly interesting for the color of its flowers.
  • A great nectar producer, the flowers from this tree will enthrall bees who will come to pollinate it.

Fruits form pods and come from flowers that cluster in very fragrant bunches of white or red when they appear in June.

The green leaves may fall off in fall without even having turned brown. They shimmer and sway and make this tree look alive.

Smaller black locust for small gardens

An interesting variety stays smaller as it grows. It’s called Robinia pseudoacacia ‘Umbraculifera’, because the canopy looks similar to an umbrella!

  • This variety doesn’t grow as tall and tops out at around 20 feet or 6 meters.

Smart tip about false acacia

Upon planting, spread some mulch at the base of the tree and you’ll avoid weed growth!


Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Black locust blooming by Valter Cirillo ☆ under Pixabay license
Upright Robinia by cifraser1 ☆ under © CC BY 2.0
Black locust branch by Melissa McMasters ★ under © CC BY 2.0