gleditsia

( gluh - DIT - see - uh )

At-A-Glance Information

Also called Honey Locust, this genus of deciduous trees needs full sun and moderate to regular water to perform at its best. These trees cast filtered shade in summertime into fall; and are great as a large specimen tree in the garden. Foliage is green and ferny, and flowers are inconspicuous and green-yellow. These trees can be messy, depending on the species grown, and all species have thorny trunks. Take care when planting these trees in your landscape, as the sharp thorns on branches and trunks can pierce and damage skin of humans and pets.

gleditsia Species and Varietals

The genus Gleditsia is a member of the plant family Fabaceae, and includes 12 species of trees. The genus name honors Johann Gottleib Gleditsch, former director of the Berlin Botanical Garden. Honey Locust grows well in zones 1-16 and 18-20. To find your zone, click here: Zone Map.

Gleditsia amorphoides
These trees are native to South America, and reach between 33 and 66 feet tall when mature. Crowns on these trees are rounded and dense, and is armed with many sharp spines. These make great natural barriers, and can be used as fencing. 

Gleditsia aquatica (Water Locust, Swamp Locust)
These trees are native to the southwestern United States and surrounding areas, and reach between 50 and 60 feet tall when mature. They are commonly seen growing in swampy areas, and prefer partial sun for best performance.

Gleditsia caspica (Caspian Locust, Persian Honeylocust)
Native to western Asia, the Caucasus, Azerbaijan, and Iran, these trees are medium-sized and deciduous, reaching 40 feet tall at maturity on average. Flowers are greenish-white 

Gleditsia japonica (Japanese Locust)
Native to Japan, China, Manchuria, and Korea, this species is used as a street tree in much of its native range. Foliage is green, flowers are inconspicuous. 

​Gleditsia sinensis (Zao Jia, Chinese Honey Locust, Black Locust)
These plants are native to Asia, and reach about 100 feet tall when they are mature. Foliage is green, and flowers are inconspicuous.
Gleditsia triacanthos (Honey Locust, Thorny Locust, Thorny Honeylocust)
​These trees are native to central and eastern North America, and have delicate foliage. They reach 35-70 feet tall and 25-35 feet wide quickly, with an upright main trunk and spreading, arching branches. Leaves are fernlike, turning yellow before dropping off the tree in early fall. In spring, these trees are late to leaf out.
'Halka'
Fast-growing variety with a strong trunk and horizontal branching pattern. Heavy seeder.
'Imperial'
Tall, symmetrical tree with a spreading habit, reaching about 35 feet tall. Dense foliage provides more shade.
'Rubylace'
New growth is red; turning bronze-green in summer and reddish in fall. Irregular growth corrected through pruning. Protect from strong winds.
'Skyline'
Pyramidal and symmetrical growth; great street tree.
'Street Keeper'
Narrow, dense, and upright habit, reaching 20 feet wide. Leaves are dark green.
'Sunburst'
Golden yellow new foliage; greenish mature leaves. Loses leaves in response to temperature change and drought. Protect from wind.
'True Shade'
Light green leaves on a strong, fast-growing tree.

Caring for and pruning gleditsia Trees

Honey Locust trees are fantastic trees for urban environments, and can be planted in a wide variety of situations. They thrive in full sun, and need at least 6 hours of direct sun exposure each day to grow vigorously. They can tolerate some light shade, especially when they are young, but do perform best in sunny locations. They prefer loamy or sandy soils that are well-draining, but are adaptable to a wide variety of soil types, including poor or even compacted soils. This makes them great candidates for street, parking lot, or front walkway trees. They can tolerate a wide range of soil pH as well, but will grow best in soils with a pH of between 6.0 and 8.0. After installing trees, apply a thick layer of mulch around the base. This will increase soil moisture retention, suppress weed growth, and regulate soil temperatures. Water newly planted trees regularly, ensuring that good drainage is occurring at all times and that plants are never left in standing water. They are drought-tolerant once established, able to get by on occasional deep waterings in summertime.

Fertilize with an application of organic compost around the base of the tree, which will help improve soil quality as well as structure and richness. Generally, these trees don't require many feedings, though if they seem to be struggling (growing slowly or producing pale leaves), they may benefit from an additional springtime feeding with a balanced, slow-release fertilizer. These trees will typically develop a strong central leader as they grow, but some pruning may be required to remove dead, damaged or crossing branches yearly. Prune these trees while they are dormant (in late winter or early springtime); this will minimize stress on the tree. These trees naturally have beautiful, open canopies and over-pruning can ruin their natural form. Yearly or every two years, simply lightly thin the canopy to increase airflow.

Propagation

Gleditsia can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your tree, follow the instructions below:

Propagating Gleditsia by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. 
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Gleditsia by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows. 
  2. Harvest your seeds. The seed pods on Gleditsia trees are pretty easy to spot, they're large and dangle from the branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. Gleditsia seeds need a cold snap in order for them to break dormancy, so they will need to be cold-stratified before planting. This can be accomplished by placing the seeds inside of a plastic bag or other sealable container filled with moistened sand or peat moss. Next, place the container or bag in the refrigerator and leave for between 1 and 3 months to mimic natural winter conditions. After this period has passed, remove them and lay them out to work with them.
  4. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  5. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home
Gleditsia seeds are contained inside of seed pods produced by trees in summertime. They will stay on the tree until well into the winter months.
Gleditsia seeds are reddish-brown and hard, and there are approximately 12-20 seeds contained inside each pod.

Problems and Pests

Gleditsia trees, although typically pest- and disease-resistant, are susceptible to the following pests and diseases:
  • Leafhoppers
  • Spider Mites
  • Pod Gall Midges
  • Mimosa Webworms
  • Leafminers
  • Canker
  • Honey Fungus
  • Leaf Spot
  • Powdery Mildew
  • Rust
For more information on these garden issues, see the following pages:
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Gallery

Gleditsia triacanthos inermis 'Emerald Cascade' has weeping foliage.
Use these trees as additions to water-wise front yard landscaping.
Gleditsia make fantastic street trees.
Gleditsia trees have beautiful fall foliage.
Take care when planting these in the garden, as their thorns can pierce clothing and skin.
These trees produce ferny foliage and reddish-brown seed capsules.

Videos

Learn about the thornless Honey locust tree.
These are beautiful landscape trees.
Learn about the Sunburst golden locust tree.
Chinese Honey Locust trees have edible parts.

Resources

Honey Locust: Description, Types, and Care Tips (Full Guide)
Planting and Care of Honey Locust
How to Grow and Care for Sunburst Honey Locust Tree
Gleditsia triacanthos (Honey Locust)
Wikipedia: Gleditsia
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 340 - 341, Gleditsia triacanthos (Honey Locust)
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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