Tree · Fabaceae
Honey Locust
Gleditsia triacanthos
Fast, tough, and eager to please, the honey locust throws dappled shade across the roughest ground you can hand it.
Full sun
Every 7–14 days
USDA 3–9
30–79 ft · 9–24 m
Overview
The honey locust is a joy to grow, and it earns that reputation fast. A quick-growing legume from central North America, named for the sweet pulp packed inside its long, twisting pods, it casts a light, dappled shade thin enough for grass and flowers to keep thriving right up to the trunk. Turn it loose and it climbs to 30 to 80 feet (9 to 24 m) with a wide, open crown, paying back huge shade for a tree that asks so little.
Almost nothing slows this tree down. It powers through clay, sand, drought, road salt, packed soil, and harsh alkaline city ground, and it shrugs off winters down to -40°F (-40°C) and summers up to 100°F (38°C) without missing a beat. That whole sweep, from zone 3 to zone 9, is why it flourishes in spots where choosier trees throw in the towel.
One thing to plan around: the wild form arms its trunk and branches with long, branched thorns and drops heavy pods. Breeders already cracked that with thornless, seedless cultivars of var. inermis, which is exactly what nurseries stock. Grab one of those and you bag all the toughness with none of the mess or the spikes, so you win on every front.
Care
The short version: hand it full sun and just about any soil, water it well through the first couple of years, then step back and watch, because a settled honey locust ranks among the most drought-tolerant shade trees you can plant.
Light
Drop a honey locust into full sun and it rewards you with the fullest crown and fastest growth. It will tough out a bit of part shade, but it really takes off, quickest and healthiest, out in the open with at least six hours of direct light a day.
Water
Soak a young tree on a regular schedule through its first one to two years while the roots race outward. After that it turns very drought tolerant and barely asks for a drink, so just let the top half of the soil dry between waterings.
Soil
Hardly any tree is this laid-back about soil. It thrives in moist, rich loam yet powers through clay, sand, poor ground, compaction, salt, and alkaline city dirt, across a wide pH band of 6.0 to 8.0.
Temperature
This tree is built for extremes and laughs off the cold, cruising from -40°F to 100°F (-40°C to 38°C). That toughness covers USDA zones 3 through 9 and lets it grow where plenty of shade trees stall out.
Humidity
Outdoor humidity never enters the picture for an established tree, so there is no level to chase. What really pays off is good air movement through the crown, since it dries the foliage and keeps mites and disease from gaining ground.
Feeding
As a legume, the honey locust mostly feeds itself and rarely wants more. Skip the fertilizer unless the soil is genuinely poor, and even then a single balanced slow-release dose in spring gets it done.
Pruning
Prune in late winter to early spring while the tree is dormant. Train it to one strong central leader while young, and cut out any crossing, dead, or damaged wood to keep the structure crisp.
Repotting
A honey locust wants the open ground, not a pot, so repotting rarely comes up. If you are holding a young one in a container, bump it up a size once roots circle the inside or push out the drainage holes.
Size & spacing
Hand this tree serious room, because it can rocket 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 the broad crown has space to fill out.
When to plant
The honey locust runs on a simple yearly rhythm that is easy to follow. Plant it in spring or fall, watch for the small fragrant flowers in late spring, and keep an eye out for the long brown pods that ripen and drop through early 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 grower, but a few pests and one serious fungus turn up often enough to learn on sight. Good news is that most of the leaf damage looks scarier than it plays out and fades on its own. The cankers are the real deal, so match what you spot below before you fire up the pruning saw.
Sunken cankers on the bark with branches dying back
Sunken, discolored lesions wrapping branches and the trunk mark Thyronectria or Nectria canker, fungi that pounce on trees already worn down by drought, wounds, or crowding. No spray beats it, so this is the one to tackle head on. Prune well below every canker in dry weather and disinfect your tools between cuts, pull a badly cankered tree before it spreads, and drive the rest to full vigor with steady water and undamaged 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 laced into silk and stripped down by midsummer
Silk webbing packed with tiny caterpillars flags the mimosa webworm, which chases golden cultivars like Sunburst harder than any other. Jump on it early: clip out the little nests the moment they appear, and treat the young caterpillars with Bt while they are still small. Rake up the litter under the tree afterward, since that is where the pupae wait out the winter, and you break the cycle.
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 riding the leaflet tips, with leaves dropping early
Those puffy, pod-like swellings on the leaflet tips are the work of the honeylocust pod gall midge, whose maggots grow up tucked inside the twisted foliage. Here is the upside: an established tree powers straight through a light hit and barely registers it. When galls really build up, spray horticultural oil across the fresh tips in March or April and snip out the worst shoots to knock the population back.
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
Twisted, undersized new growth in spring
Warped or stunted spring leaves usually trace back to the honeylocust plant bug feeding on the soft new growth, and it looks a whole lot rougher than it plays out. The tree charges right past it, so light early feeding is fine to leave be. Catch fine stippling and webbing later in the summer heat instead, and you have spider mites, which a hard blast of water or a shot of insecticidal soap sends packing.
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
Great news for a home full of animals: the honey locust is safe. The ASPCA lists it as non-toxic to dogs, cats, and horses, and livestock and wildlife feast on the sweet pods every fall. The only real hazard is a physical one, the long sharp thorns on wild trees, which is exactly why landscape cultivars come bred thornless.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cats get a full pass here. Let one swat a fallen leaflet or gnaw a twig, and no poisoning follows.
Dogs None
Dogs are clear to romp around it. A pup that chews a dropped pod may load up on roughage, but the tree packs no toxin whatsoever.
Horses None
Horses graze right up to it with zero risk, and they treat the sweet pods as a welcome snack rather than a threat.
Rabbits Safe
Rabbits have no poison to dodge here. The bark and twigs are just rough browse, nothing dangerous.
Livestock None
The pods land as palatable, nutritious feed that stock devour without ill effect. Cattle, goats, and sheep have thrived on them for generations.
Birds Safe
Birds do great around it, and wildlife strips the sweet pods clean every fall without a hitch.
People Safe
People have snacked on the sweet pulp from ripe pods for ages, so there is no poison worry. The real catch is the wild form's long, sharp thorns, so handle thorny trunks with care.
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 sold for a yard or street is a named thornless cultivar, so you can dive in with confidence. These are the ones you will run into most.
Shademaster
A vigorous, thornless and nearly seedless powerhouse with a vase shape and branches that sweep upward, which has stormed its way to street-tree stardom on sheer toughness.
Skyline
A thornless, podless cultivar that climbs in a crisp pyramid on a strong central leader and torches into clean golden-yellow when fall arrives.
Sunburst
A thornless, seedless selection that gardeners chase for its bright golden new foliage, even though it is the one mimosa webworm and pod gall midge target first.
Imperial
A thornless, seedless cultivar that holds a compact, rounded shape on neat horizontal branches, slipping easily into a tighter yard.
var. inermis
The naturally thornless botanical form, its name meaning unarmed, and the launch point for nearly every landscape cultivar out there.
How to propagate
Growing a honey locust from its own seed is a fun project, but the named cultivars play by different rules and have to be cloned to hold onto their best traits.
SeedModerate
Spring after collecting ripe pods in fall · 1 to 2 growing seasons to a transplantable seedling
Grab ripe pods in fall and sow in spring, but crack the hard, waterproof seed coat first with a file, hot water, or concentrated sulfuric acid, or nothing pushes up. Let the seedling run for one to two growing seasons to reach transplant size. Keep in mind that a thornless parent throws mixed offspring, 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 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 locks the exact clone in place, and the young tree digs 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 catching heat meant for the black locust (Robinia pseudoacacia), a totally different tree that people mix it up with. Honey locust is non-toxic, and livestock and wildlife feast on its sweet pods. Black locust is the one packing the toxalbumins that poison dogs and horses, not this tree.
A honey locust in the yard will grow vicious thorns and drop messy pods.
True, the wild tree bristles with fierce branched thorns and long pods, but that is not what nurseries hand you. Most landscape trees are thornless cultivars of var. inermis, and loads of them come seedless and podless on top of that, so the mess never shows.