Honey locust, a sweet giant – with massive thorns!

Honey locust planting and care

If you’ve got a large garden, go ahead and plant a Gleditsia triacanthos, you’ll savor its cool shade during summer. And, you’ll marvel at the honey locust‘s sweet fall fruit pods in fall and winter.

Gleditsia triacanthos key facts

Botanical nameGleditsia triacanthos
Family – Fabaceae
Type – tree

Height – up to 90 feet (30 m)
Exposure – sun to part shade
Soil – fertile, well drained

Hardiness – hardy 5 to 23°F (-5 à -15 °C)
Growth – average to fast

Foliage – deciduous
Fruit formation – end of summer, fall
Flowering – beginning of summer (insignificant)

Introducing: Honey Locust

Common names: Honey locust, sweet bean tree, honey shucks locust, thorny locust…

The list says it all: thorns, sweet fruits… an interesting mix!

This tree is native to North America. The plus-sized growth of this tree and its magnificent foliage make this tree a welcome haven of shade to fight off extreme summer heat. The most significant point – literally – of honey locust are the many thorns along the trunk and branches.

Thorns that breeders have tried to get rid of

  • Happily, nowadays many varieties exist that are inermis, meaning: thornless (Gleditsia triacanthos ‘Inermis’).

Interesting pods appear after the flowers, they readily sproutThe small panicle-like flowers of Gleditsia triacanthos aren’t beautiful, not in themselves. But they do turn into surprising giant seed pods that are very ornamental. These pods even hang to the tree long after leaves have dropped in fall. In addition, these fleshy pods are a boon for cooking: their sweet flesh is edible and you can use it to directly replace sugar.

The more adventurous among us can even try to ferment it to brew beer.

Leaves of honey locust are somewhat similar to those of black locust. They’re up to 8 inches long (20 cm), with many oval leaflets. When fall comes around, they slowly take on a gold-yellow hue.

Did you know… ? The elegant Gleditsia triacanthos is sometimes also called Thorns of Christ: it’s said that the Crown of thorns that Jesus wore during the passion was wrought from this tree’s branches.

Planting honey locust

Plant honey locust as a standaloneBranches of Gleditsia triacanthos are rather fragile, so it’s best to find a spot for it that is sheltered from strong winds. As for the soil, make sure it drains well enough, is deep and rich with lots of organic matter. Soil pH won’t matter. Regarding exposure, the sweet bean tree prefers sunny spots, though it can still make do with part shade.

When to plant Gleditsia triacanthos ?

Older trees are hardier and won’t suffer much from the cold, but younger plants aren’t as resistant. In addition, honey locust deals pretty well with drought. As a consequence, the best time to plant your tree is at the beginning of spring. If needed, though, you can still of course plant in fall, but you’ll have to protect the tree during that first winter.

How to plant thorny locust?

After selecting the right spot, simply:

  • Dig a large hole about 12 to 16 inches (30 to 40 cm) wide and deep.
  • Amend the soil with sand, soil mix or well-broken-down compost.
  • Remove the pot and extract the clump; break the root ball up a bit to spread the roots to all sides. If you’ve bought bare-root saplings, root dip is the way to go to help them settle in better.
  • Place your Gleditsia triacanthos in the planting hole, together with a stake wedged in right by the trunk (watch out for roots).
  • Backfill the hole, pressing the soil down well. Tether the tree to the stake with a special “8” knot, which stays in place without strangling the trunk.
  • Water abundantly.

Propagating honey locust

You can get new thorny locust specimens either through seeds (sow in fall) or by grafting (shield grafting) at the end of summer.

Caring for Gleditsia triacanthos

Thorny locust does require a little bit of maintenance during the first few years of growth:

  • In summer, check if any watering is needed, during dry spells mostly: the tree needs a few years to send its roots out far and wide.
  • In winter, if it gets very cold in your area or if a harsh freezing is announced, protect your young Gleditsia triacanthos with winterizing fleece.

Diseases and pests on Gleditsia triacanthos

A resilient tree, honey locust isn’t vulnerable to diseases, nor does it fall victim to parasite insects and pests.

Landscaping uses

Gleditsia triacanthos leaves in autumnThe massive size of Gleditsia triacanthos means it can only fit in large gardens and parks.

It can grow there as a standalone or in a row, alongside a road or walkway.

Since it resists pollution very well, it even serves to decorate streets.

Image credits (edits Gaspard Lorthiois):
Pixabay: Erika Varga
CC BY-SA 2.0: Danny Schissler for the Plant Image Library
Public Domain: szántó
CC BY 2.0: Jesús Cabrera