Tree · Fabaceae
Honey Locust
Gleditsia triacanthos
Fast, hardy, and endlessly forgiving, the honey locust lays a soft dappled shade across the hardest corners of a property.
Full sun
Every 7–14 days
USDA 3–9
30–79 ft · 9–24 m
Overview
Few trees dress a difficult yard as gracefully as the honey locust. A fast-growing legume from central North America, named for the sweet pulp within its long, twisting pods, it filters the afternoon into a light, dappled shade open enough that a lawn, a border, and a seating area all carry on beneath it. Given room, it rises to 30 to 80 feet (9 to 24 m) with a broad, open crown that reads as a calm canopy over a patio or drive rather than a heavy ceiling.
What sets it apart for a home is how little the site has to offer. It settles into clay, sand, drought, road salt, packed soil, and the alkaline ground along a city sidewalk, and it holds its poise through winters at -40°F (-40°C) and summers at 100°F (38°C). That reach from zone 3 to zone 9 makes it the tree for the awkward strip, the parking edge, or the exposed corner where a more delicate species would sulk.
The one point of care is the wild form, which arms its trunk and branches with long, branched thorns and drops heavy pods across a walk. Growers set that right with thornless, seedless cultivars of var. inermis, the versions the nurseries stock, so the tree brings its filtered light and easy manners to a garden without leaving litter or hazard underfoot.
Care
The short version: full sun and almost any soil suit it, so water it well through the first couple of years, then step back and let it settle, because a mature honey locust is among the most drought-tolerant shade trees a home can rely on.
Light
Give a honey locust full sun and it rewards the setting with its fullest crown and best growth. It will accept a little part shade, but it comes into its own, quickest and healthiest, out in the open with at least six hours of direct light a day.
Water
Water a young tree on a regular schedule through its first one to two years while the roots settle into their new place. After that it turns very drought tolerant and rarely asks for a thing, so let the top half of the soil dry between waterings and let the tree take over.
Soil
Few trees are so gracious about their footing. It prefers moist, rich loam yet takes clay, sand, poor ground, compaction, salt, and alkaline city soil in stride, across a generous pH band of 6.0 to 8.0.
Temperature
This is a cold-hardy tree made for a demanding climate, at ease from -40°F to 100°F (-40°C to 38°C). That resilience carries it across USDA zones 3 through 9 and lets it grace gardens where many shade trees would falter.
Humidity
Outdoor humidity never enters into it for an established tree, so there is no level to manage. Good air movement through the crown does the useful work, drying the foliage and keeping mite and disease pressure low.
Feeding
As a legume, the honey locust largely provides for itself and asks little in the way of feeding. Leave the fertilizer aside unless the soil is genuinely poor, and then a single balanced slow-release dose in spring is plenty.
Pruning
Prune in late winter to early spring while the tree is dormant. Guide a young specimen to one strong central leader, and take out any crossing, dead, or damaged wood so the frame reads clean against the sky.
Repotting
A honey locust belongs in the open ground rather than a container, so repotting rarely comes up. If a young tree waits in a pot, move it on once the roots circle the inside or slip out the drainage holes.
Size & spacing
Plan for scale, because this tree reaches 30 to 80 feet (9 to 24 m) tall and spreads 25 to 50 feet (8 to 15 m) wide. Give it clearance from buildings, walls, and neighboring trees so the broad crown can open into the space it deserves.
When to plant
The honey locust keeps an easy annual rhythm that fits neatly into the garden year. Set it out in spring or fall, enjoy the small fragrant flowers of late spring, and watch the long brown pods color and fall through the early weeks of autumn.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or fall
- Harvest: Inconspicuous fragrant greenish-yellow flowers in late spring (May to June); flat twisted brown seed pods ripen September to October.
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
A honey locust is a steady presence in a garden, yet a few pests and one serious fungus appear often enough to recognize at a glance. Most of the foliage trouble looks worse from the terrace than it proves to be. The cankers are the exception worth taking seriously, so match what the tree shows below before any cuts are made.
Sunken cankers on the bark with branches in decline
Sunken, discolored lesions circling branches and the trunk are the mark of Thyronectria or Nectria canker, fungi that settle into trees already worn by drought, wounds, or crowding. No spray reverses it, so this is the trouble that deserves real attention. Prune well below each canker in dry weather with tools disinfected between cuts, remove a badly cankered tree before it spreads, and sustain the rest with steady water and unblemished bark.
Fix:
- Prune out infected branches well below the canker during dry weather and disinfect tools
- Remove and destroy severely cankered trees
- Improve vigor with proper watering and avoid bark wounds
Leaflets veiled in silk and stripped bare by the height of summer
Silky webbing threaded with small caterpillars is the calling card of the mimosa webworm, which favors golden cultivars such as Sunburst above all others. Clip away the small nests the moment they appear, and treat the young caterpillars with Bt before they spread. A tidy autumn cleanup of the litter beneath the canopy, where the pupae overwinter, keeps next season looking its best.
Fix:
- Prune out and destroy small webbed nests early
- Apply Bt (Bacillus thuringiensis) while caterpillars are small
- Clean up debris beneath the tree where pupae overwinter
Pod-shaped swellings on leaflet tips and an early thinning of the canopy
The swollen, pod-like growths at the leaflet tips belong to the honeylocust pod gall midge, whose maggots mature within the deformed foliage. A settled tree carries a light visitation with ease and comes to no lasting harm. Should the galls grow conspicuous, a horticultural oil on the new tips in March or April, paired with the removal of the worst shoots, restores a clean line to the crown.
Fix:
- Tolerate light infestations on established trees, which are rarely killed
- Apply horticultural oil to terminals in March-April to kill eggs
- Prune and destroy heavily galled shoots
Warped, undersized spring foliage
Warped or dwarfed spring leaves usually come down to the honeylocust plant bug, which feeds on the soft new growth and leaves damage that reads worse than it truly is. The tree grows past it, so a little early feeding is nothing to dwell on. When fine stippling and webbing arrive in the summer heat, spider mites are the culprits, and a firm spray of water or a dose of insecticidal soap sets things right.
Fix:
- Tolerate minor early-season plant bug damage; trees usually recover
- Hose down foliage to dislodge spider mites
- Use insecticidal soap or horticultural oil for heavy mite outbreaks
Toxicity
For a home that shares its grounds with animals, the verdict is reassuring: the honey locust is safe. The ASPCA lists it as non-toxic to dogs, cats, and horses, and livestock and wildlife take the sweet pods each autumn without harm. The only real hazard is a physical one, the long sharp thorns of wild trees, which is exactly why landscape cultivars are chosen thornless.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The household cat has nothing to fear here. A paw at a fallen leaflet or a chewed twig leads to no poisoning.
Dogs None
Dogs share the garden safely. A pup that works on a dropped pod may take in more roughage than it bargained for, yet the tree holds no toxin.
Horses None
Horses graze nearby without concern, and the sweet pods read as a small treat rather than a threat.
Rabbits Safe
Rabbits face no poison in this planting. The bark and twigs are simply coarse browse, nothing more worrying.
Livestock None
The pods make palatable, nourishing feed taken without ill effect. Cattle, goats, and sheep have grazed on them for generations.
Birds Safe
Birds keep company with it untroubled, and wildlife carries off the sweet pods every autumn without any harm.
People Safe
The sweet pulp within the ripe pods has nourished people for generations. The one genuine hazard is the wild form's long, sharp thorns, so a thorny trunk asks for a careful hand.
The wild species bears large, sharp, branched thorns on the trunk and branches that can cause puncture injuries; landscape cultivars are typically thornless.
Varieties
Nearly every honey locust offered for a yard or a street is a named thornless cultivar, each with its own presence in a landscape. These are the ones a gardener meets most often.
Shademaster
A vigorous, thornless and nearly seedless selection with a graceful vase silhouette and ascending branches, long relied on as a poised and dependable street tree.
Skyline
A thornless, podless cultivar with a composed pyramidal outline on a strong central leader, closing the year in clean golden-yellow.
Sunburst
A thornless, seedless selection sought for its bright golden new foliage, though it is also the one that draws mimosa webworm and pod gall midge most readily.
Imperial
A thornless, seedless cultivar that keeps a compact, rounded form on neat horizontal branching, an easy fit for a more intimate setting.
var. inermis
The naturally thornless botanical form, its name meaning unarmed, the quiet parent from which most landscape cultivars descend.
How to propagate
A honey locust can be raised from its own seed, but the named cultivars are another matter and must be cloned to hold the character that earns them a place in a designed space.
SeedModerate
Spring after collecting ripe pods in fall · 1 to 2 growing seasons to a transplantable seedling
Gather the ripe pods in autumn and sow the seed in spring, though the hard, waterproof coat has to be opened first with a file, hot water, or concentrated sulfuric acid, or germination will not follow. The seedling needs one to two growing seasons to reach transplant size. Bear in mind that a thornless parent does not pass the trait down cleanly, since only about 60 percent of the offspring emerge thornless.
GraftingDemanding
Late winter to spring (grafting) or summer (budding) · 1 to 2 growing seasons
Because the named thornless, seedless cultivars never come true from seed, nurseries graft them in late winter to spring or bud them onto seedling rootstock in summer. That preserves the exact clone, and the young tree settles into its place over one to two growing seasons.
Myths
Honey locust is poisonous to pets and livestock, like the other locust trees.
Honey locust inherits a reputation that belongs to the black locust (Robinia pseudoacacia), a separate tree it is often mistaken for. Honey locust is non-toxic, and its sweet pods feed livestock and wildlife. It is black locust that holds the toxalbumins which poison dogs and horses.
A honey locust planted in the yard will grow vicious thorns and drop messy pods.
The wild tree does carry fierce branched thorns and long pods, but that is not the tree a nursery offers. Most landscape trees are thornless cultivars of var. inermis, and many are seedless and podless besides, sparing the garden the litter entirely.