Tree · Fabaceae
Honey Locust
Gleditsia triacanthos
Tough, quick, and easy to please, the honey locust drops dappled shade over ground where hardly anything else will settle.
Full sun
Every 7–14 days
USDA 3–9
30–79 ft · 9–24 m
Overview
So what makes the honey locust such a popular yard tree? It's a fast-growing legume from central North America, named for the sweet pulp tucked inside those long, twisting pods, and it throws a light, dappled shade that's thin enough for grass and flowers to keep growing right up to the trunk. Left on its own it can hit 30 to 80 feet (9 to 24 m) with a wide, open crown, so it gives you a lot of shade for a tree that asks so little.
Honestly, almost nothing bothers it. It handles clay, sand, drought, road salt, packed-down soil, and harsh alkaline city ground, and it takes winters down to -40°F (-40°C) and summers up to 100°F (38°C) in stride. That whole range, from zone 3 to zone 9, is why you'll spot it growing happily in spots where pickier trees just give up.
There's one catch, and it's the wild form. It arms its trunk and branches with long, branched thorns and drops heavy pods all over. Good thing growers already fixed that with thornless, seedless cultivars of var. inermis, which is what the nursery hands you anyway. Pick one of those and you get all the toughness without the mess or the spikes, so where's the downside?
Care
The short version: give it full sun and pretty much any soil, water it well for the first couple of years, then back off and let it do its thing, because a settled honey locust is one of the most drought-tolerant shade trees you can plant.
Light
Pop your honey locust in full sun and you'll get the fullest crown and the best growth. It'll put up with a bit of part shade, sure, but it grows fastest and stays healthiest out in the open with at least six hours of direct light a day.
Water
Give a young tree a regular soak through its first one to two years while the roots stretch out and find their footing. After that? It's very drought tolerant and hardly ever asks for a drink, so just let the top half of the soil dry out between waterings.
Soil
Not many trees are this laid-back about soil. It loves moist, rich loam, but it'll happily take clay, sand, poor ground, compaction, salt, and alkaline city dirt, across a wide pH band of 6.0 to 8.0.
Temperature
This tree's built for extremes and shrugs off the cold, comfy anywhere from -40°F to 100°F (-40°C to 38°C). That toughness covers USDA zones 3 through 9 and lets it grow where a lot of shade trees can't.
Humidity
Outdoor humidity? Never a thing for an established tree, so there's no level to worry about. What actually helps is good air movement through the crown, since it dries the foliage and keeps mites and disease from getting a foothold.
Feeding
Being a legume, the honey locust mostly feeds itself and rarely wants more. Skip the fertilizer unless the soil's genuinely poor, and even then just one balanced slow-release dose in spring does the job.
Pruning
Prune in late winter to early spring while the tree's still dormant. Train it to one strong central leader when it's young, and clip out any crossing, dead, or damaged wood to keep things clean and open.
Repotting
A honey locust really wants to be in the ground, not a pot, so repotting rarely comes up. If you're holding a young one in a container for now, just bump it up a size once the roots start circling inside or poking out the drainage holes.
Size & spacing
Give this tree some real elbow room, because it can shoot up to 30 to 80 feet (9 to 24 m) tall and spread 25 to 50 feet (8 to 15 m) wide. Set it well clear of buildings, walls, and other trees so that big crown has room to fill out.
When to plant
The honey locust keeps a pretty simple yearly rhythm, so there's not much to keep track of. Plant it in spring or fall, look for the small fragrant flowers in late spring, and watch the long brown pods ripen and drop through the early part 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 tough customer, but a few pests and one serious fungus show up often enough that it's worth knowing them on sight. Good news is that most of the leaf damage looks scary and really isn't. The cankers are the exception you actually want to worry about, so match what you're seeing below before you grab the pruning saw.
Sunken bark cankers with branches dying back
Sunken, off-color patches wrapping around a branch or the trunk are the sign of Thyronectria or Nectria canker, fungi that sneak in when a tree's already run down by drought, wounds, or crowding. There's no spray that'll cure it, so this is the one to take seriously. Prune well below each canker in dry weather and wipe your tools clean between cuts, take out a badly cankered tree before it spreads, and keep the rest strong with steady water and no bark damage.
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 caught in silk and chewed to lace by midsummer
See little caterpillars huddled inside silky webbing? That's almost always the mimosa webworm, and it goes after gold-leaved types like Sunburst harder than the rest. Snip off the small nests as soon as they turn up, and hit the young caterpillars with Bt while they're little. Then rake up the mess under the tree, because that's where the pupae ride out the winter.
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
Puffy pod-shaped lumps on leaflet tips, with leaves dropping early
Those weird swollen lumps on the leaflet tips? That's the honeylocust pod gall midge, and its maggots grow up inside the deformed foliage. Here's the good news: a grown tree just shrugs off a light hit and hardly notices. If the galls really pile up, though, spray a little horticultural oil on the fresh tips in March or April, and cut out whatever shoots look worst.
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
Crinkled, undersized new leaves in spring
Puckered or stunted spring leaves usually just mean the honeylocust plant bug has been snacking on the soft new growth, and honestly it looks a lot worse than it is. The tree grows right past it, so there's no need to fuss over that early feeding. See fine speckling and webbing later in the summer heat instead? That's spider mites, and a strong blast of water or a bit of insecticidal soap sorts them out.
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
Got animals at home? Good news, because the honey locust is safe. The ASPCA lists it as non-toxic to dogs, cats, and horses, and livestock and wildlife eat the sweet pods every fall without any trouble. The only real hazard is a physical one, the long sharp thorns on wild trees, and that's exactly why landscape cultivars are bred thornless.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
No worries with the cat here. If one paws at a fallen leaflet or nibbles a twig, it won't get poisoned.
Dogs None
Dogs are fine too. A pup that chews a dropped pod might get a bit more roughage than its tummy wants, but there's no toxin in the tree itself.
Horses None
Horses can hang out around it no problem, and honestly the sweet pods are more of a treat than anything to fear.
Rabbits Safe
Rabbits have nothing to worry about. The bark and twigs are just rough browse, not anything that'll hurt them.
Livestock None
The pods make good, tasty feed and go down without any trouble. Cattle, goats, and sheep have been eating them for ages.
Birds Safe
Birds are perfectly fine around it, and wildlife clears out the sweet pods every fall without any bother.
People Safe
People have been eating the sweet pulp from ripe pods for a long time, so that's not the concern. The thing to watch is the wild form's long, sharp thorns, so go easy on a thorny trunk.
The wild species bears large, sharp, branched thorns on the trunk and branches that can cause puncture injuries; landscape cultivars are typically thornless.
Varieties
Just about every honey locust you'll find for a yard or a street is a named thornless cultivar, so you don't have to guess. These are the ones you're most likely to bump into.
Shademaster
This one's a vigorous, thornless and nearly seedless pick with a vase shape and branches that sweep upward, and it's earned its spot as a tough, dependable street tree.
Skyline
Skyline is thornless and podless, grows in a neat pyramid on a strong central leader, and turns a clean golden-yellow when fall rolls around.
Sunburst
Sunburst is thornless and seedless, and people plant it for that bright golden new foliage, though it's also the one that catches mimosa webworm and pod gall midge more than the rest.
Imperial
Imperial is a thornless, seedless cultivar that stays nice and compact and rounded, with tidy horizontal branches that make it easy to place.
var. inermis
This is the naturally thornless botanical form, and its name actually means unarmed, which is fitting since most landscape cultivars got selected right from it.
How to propagate
You can grow a honey locust from its own seed if you want, but the named cultivars are a whole different story, and you've got to clone them to keep what makes them special.
SeedModerate
Spring after collecting ripe pods in fall · 1 to 2 growing seasons to a transplantable seedling
Grab the ripe pods in fall and sow them in spring, but here's the catch: the seed coat is hard and waterproof, so you've got to nick it open with a file, hot water, or concentrated sulfuric acid first, or nothing sprouts. Then give the seedling one to two growing seasons to get big enough to move. And keep in mind, a thornless parent doesn't pass it on cleanly, since only about 60 percent of the seedlings come up thornless.
GraftingDemanding
Late winter to spring (grafting) or summer (budding) · 1 to 2 growing seasons
Since those 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's how they keep the exact clone going, and the young tree settles in over one to two growing seasons.
Myths
Honey locust is poisonous to pets and livestock, just like the other locust trees.
Honey locust keeps getting blamed for what the black locust (Robinia pseudoacacia) does, since the two trees are easy to mix up. But honey locust is non-toxic, and its sweet pods feed livestock and wildlife just fine. It's black locust that carries the toxalbumins that poison dogs and horses, not this one.
A honey locust in the yard is going to grow vicious thorns and drop messy pods.
Sure, the wild tree grows those fierce branched thorns and long pods, but that's not what you're buying at the nursery. Most landscape trees are thornless cultivars of var. inermis, and plenty of them are seedless and podless too, so the mess never really shows up.