Honey Locust vs Black Locust: Key Differences

When it comes to choosing between honey locusts vs black locust trees, there are a few key differences you should be aware of. 

For one, honey locusts have thorns while black locusts don’t.

Honey locusts also typically grow taller than black locusts and their pods are more elongated.

Both honey locusts and black locusts need plenty of sunlight and well-draining soil to thrive, but honey locusts are a bit more drought tolerant than black locusts.

Honey locusts also tend to be more resistant to pests and diseases.

The honeylocust is a deciduous tree having flower clusters and long, flat seedpods. The black locust is also a deciduous tree but has short, curved seedpods.

In general, honeylocust flowers are cream-colored while black locust flowers are yellowish-green with drooping branches. 

The bark of the honeylocust is shaggy with ridges while that of the black locus is grooved. Some trees have thorns on the trunk, branches, or twigs.

These trees can be either a honeylocust or a black locus depending on other criteria such as leaf shape and fruit color.

Honeylocust trees are not poisonous to horses. However, the seeds of the black locus are very poisonous in all stages of maturity. 

The plant contains glycoside that has toxic effects on animals. Forty-two grams of this compound in a horse’s digestive tract can cause heart failure and death within two days.

If you’re looking for a fast-growing tree that is drought tolerant and pest resistant, a honey locust is a good option. However, if you’re looking for a tree that has showy flowers, the black locust is a better choice.

Differences Between Honey Locust And Black Locust 

1. Looks – Appearance

The honey locust tree is usually identified by its bark, which is an ash-gray color with distinct interlacing ridges. The thorns it produces are also unique in that they prompt some small-scale regeneration of the forest canopy where it occurs. 

Honey locust trees have compound leaves, meaning they are made up of many smaller leaflets attached to a central stem, while black locusts do not possess this trait.

2. Leaves – Appearance

Black locust trees are identifiable by their compound leaves which are each composed of 11 to 21 smaller leaflets growing off a central stalk.  

Honey Locust Leaf on the other hand has mostly 7 lobed leaves that are made up of smaller leaflets.  

Thus it can be concluded that Black Locust has more lobes in leaves compared to the Honey Locust tree.

Another key difference is the leaf size – The Leaflets of black locusts are 2-3 inches long, while leaves on honey locust trees generally range between 3-6 inches long.

It should also be noted that while the overall shape varies greatly, most leaves have either an odd number or an even number of leaflets (though five and seven are the most common numbers).    

So this points out that Honey Locust leaves possess 7 distinct lobes which distinguish them from Black Locust.

3. Flowers & Seeds – Appearance

The main way to distinguish between honey locusts and black locust trees is by their fruit. The seed pods of the black locust tree, which may hang around through winter, are thin and long with flat seeds packed tightly inside. 

Honey locust fruits on the other hand contain thick seed pods that appear almost spherical.  This is because they develop within each leaf scar and form a bulging outgrowth somewhat resembling a small pineapple.

4. Fruits – Appearance

Also called legumes, Honey Locust fruits are edible for humans as well as many animals but the Black Locust’s fruits are considered poisonous. Thus this can be concluded that Black Locust is toxic whereas Honey Locust is not.

Black Locust fruits contain condensed tannins that make them unpalatable to humans and many other animals. 

Black locust trees produce a brown, dry pod with long seeds tightly packed inside like the Honey Locust tree but unlike the latter, they appear flat on both sides.  

On the contrary, Honey locust trees produce a green fruit; while it appears similar in shape and size to black locust pods, inwardly its seed is egg-shaped and less densely packed than black locust pods. 

5. Bark – Texture

The bark of the black locust tree is smooth and gray, while the honey locust has a rougher texture and is a light ash gray color.

6. Growth Rate – Speed

Black locusts grow faster than honey locusts.

7. Nutrient Content – General

Both black locusts and honey locusts are nitrogen fixers; that is, they can take nitrogen from the air and convert it into a form that plants can use.

8. Strength – Resistance to Disease/Pests

Black Locust trees are also more resistant to disease and pests when compared to the Honey Locust.

9. Strength – Resistance to Disaster

It is also more difficult for black locusts to be uprooted by wind or ice, making them better suited for planting near roads and other areas where they must occasionally deal with high winds.     

10. Preferred Habitat/Ecology – Location Differences

The black locust prefers full sun and moist, well-drained soils; the honey locust can handle both sun and shade, as well as dryer soils. This proves that Black Locust trees have full sunlight while Honey Locust trees can tolerate a bit of shade.

Honey locust 

Similarities Between Honey Locust And Black Locust

Honey locust and black locust trees are both native to North America. Both trees have pinnately compound leaves, with 15-25 leaflets per leaf. 

The leaflets are elliptical and have smooth edges. The trees also have small, green flowers that produce small, bean-like fruits.

Both honey locust and black locust trees are fast-growing and can reach heights of 60-70 feet. They are also both drought tolerant and resistant to pests and diseases. 

However, a honey locust is a bit more forgiving than black locust; it can tolerate poorer soil conditions and needs less water.

Honey locust and black locust trees make great shade trees for residential landscapes. They provide ample shade, which is especially useful on hot summer days. They are also both tolerant of pollution and make good street trees.

Both trees feature compound leaves, with 15-25 oblong leaflets per leaf. They also produce small flowers (that appear in spring) and bean-like fruits that start green but turn brown when mature. 

If you’re not sure what kind of tree you have, you can leave the fruit on the ground for several weeks to see if it sprouts, as an acorn would.

Black locust

Care tips

Honey Locust (Gleditsia triacanthos)

The Honey locust is a popular tree for many gardens because of its beautiful shade canopy and large thorns. This thorny tree sometimes has yellow flowers after the leaves come out in spring which adds an extra splash of color. 

The bark on this tree can be brownish-gray with greenish hues, dark gray, blackish-brown, or nearly white depending on how much sun exposure it gets each year.

The Honey locust is a native of the central and eastern United States. It grows best in zones 4-8.

Honey locusts are long-lived trees and can reach a height of 40-60 feet tall at maturity. They grow quickly and can start producing shade within 10 years after planting. They do well in many soil types but prefer moist, well-drained soils.

Watering: Newly planted honey locusts should be watered weekly for the first year, then every other week for the second year. After that, they should only need to be watered during periods of drought. A deep watering once a week is better than frequent shallow waterings. 

Fertilizing: A light feeding with a slow-release fertilizer in early spring will help boost growth. 

Mulching: Using a thick layer of mulch around the tree’s base will keep weeds at bay, prevent soil erosion and reduce moisture evaporation. It should be applied after planting and replenished each year. 

Pruning: Young trees should be pruned to develop a good branch structure. Peeling or sawing off large branches can also be done to train this tree into an espalier form if desired. 

Thinning out selectively to open up the canopy is usually all that is needed once it is mature, otherwise overcrowded branches can overbear and break under their weight.

Spacing: Honey locust trees should be planted about 10-15 feet apart depending on the desired form and growth rate.

Black Locust (Robinia pseudoacacia)

The Black locust is a fast-growing tree that can reach a height of 60-80 feet at maturity. It has beautiful white flowers in the spring and dark green leaves that turn yellow in the fall. The bark on this tree is gray with black streaks but becomes nearly black with age.

The Black locust is a native of the eastern United States. It grows well in zones 4-8.

Watering: Newly planted black locusts should be watered weekly for the first year, then every other week for the second year. After that, they should only need to be watered during periods of drought. A deep watering once a week is better than frequent shallow waterings. 

Fertilizing: A light feeding with a slow-release fertilizer in early spring will help boost growth. 

Mulching: Using a thick layer of mulch around the tree’s base will keep weeds at bay, prevent soil erosion and reduce moisture evaporation. It should be applied after planting and replenished each year. 

Pruning: Young trees should be pruned to develop a good branch structure. Peeling or sawing off large branches can also be done to train this tree into an espalier form if desired. 

Thinning out selectively to open up the canopy is usually all that is needed once it is mature, otherwise overcrowded branches can overbear and break under their weight.

Spacing: Black locust trees should be planted about 15-20 feet apart depending on the desired form and growth rate.

Conclusion

Overall, both honey locusts and black locusts make good trees for planting in urban areas. 

However, honey locusts may be the better choice for hotter climates or areas with limited water resources.

Additionally, honey locust pods are a nutritious snack that can be enjoyed by people and wildlife alike.