Black Locust Tree, Yellow Locust

Robinia pseudoacacia in all its Golden Glory

The black locust tree is valued as much for the high, filtered shade cast by its ferny foliage as for the brilliant shades of yellow and gold those same leaves add to the fall landscape. Robinia pseudoacacia is also a fast growing tree.



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from: Nature Hills Nursery, Inc.

Purple Robe Locust Tree
from: Nature Hills Nursery, Inc.

Most cultivars feature green foliage which colors in autumn but there is one called 'Frisia' whose leaves emerge yellow-green each spring and retain this coloration until they drop in late fall.

No matter which cultivar of R. pseudoacacia you plant, its bright fall foliage is sure to stand out against the darker leaves of the evergreen trees and shrubs in your landscape.

Although the black locust is a large, deciduous tree, it does not create a maintenance problem. Its leaves, being comprised of many small oval-shaped leaflets, melt gently into the soil after they descend and do not need to be raked up.

If this is not enough to recommend it, the black locust tree also flowers.

The white flowers of the Black Locust tree.

The small, white pea flowers dangle from the trees in fragrant clusters and make quite a show when they appear. They are followed by bean-like pods which contain the tree's seeds.

Tip for Growing Black Locust Trees

Golden Robinia, Marysville, Victoria, Australia, Pacific
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Black locust wood is brittle and thorny. It is best to site the trees away from foot paths and outdoor play or seating areas.

The trees are also large (to 80 feet tall at maturity) and tend to sucker from their roots.

Siting a black locust tree in the center of a large lawn is an excellent idea for several reasons:

  1. The mower will take care of any suckers that form before they have a chance to gain a foothold.
  2. Grass grows beautifully beneath black locust trees as they do not cast a dense shade.
  3. Robinia trees will not tolerate shade. Being the focal point in a lawn guarantees them the sun they need to grow quickly into gorgeous landscape specimens.

This is a hardy plant which will readily adapt to most soil types. Water it regularly until it has settled in (1 year or so) and developed some drought tolerance.

It acclimates well to both heat and cold. Plant it in zones 4-9 for best performance.


Pruning a Black Locust Tree

Robinia pseudoacacia only needs training when it is young to establish a strong framework. Once the tree has grown too large to prune easily, it will no longer require yearly pruning.

Locust trees are usually trained to a central leader:

  • Remove any upright stem that competes with the central leader (which is just an extension of the tree's trunk).
  • Select 3-5 of the branches growing outward from the turnk as scaffold branches. Scaffolds should not be directly above one another and should form wide crotches from the trunk as narrow crothes are weak. Remove all other branches.
  • Each year select another set of scaffold brahches 2-3 feet higher up the trunk than the first set. Do this until the tree has 3 or 4 sets of scaffold limbs.
  • Once this occurs, all you will need to do is prune off any broken or crossing wood and thin the canopy to allow strong winds to pass through without breaking limbs. Most years you won't need to do any trimming at all.

Similar Trees:

The Honeylocust is a Black Locust Lookalike without the Thorns

For Stunning Fall Color, Plant a Golden Rain Tree

Related Pages:

How to Stop Locust Insects from Ruining Your Yard

Find Out Which Electric Pole Saw Does Not Make the Cut

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