Kentucky coffeetree
Gymnocladus dioicus
A rugged prairie-edge native with huge doubly-compound leaves, bold scaly bark, and near-total indifference to drought, cold, salt and pollution: the street tree cities reach for as the ashes go.
- Type
- Tree · Perennial
- Botanical family
- Legume (pea & bean family)
- Foliage color
- Green · Gold and chartreuse
- Sunlight
- Full sun
- Watering
- Low once established
- Soil
- Adaptable; deep and moist for preference, alkaline and dry without complaint
- Feeding
- All-purpose balanced
- USDA zones
- 3b–8b
- Frost tolerant
- Yes
- Plant out
- 14 days before the last spring frost
- Plant spacing
- 36 ft 1 in
- In-row spacing
- 29 ft 6 in
- Between rows
- 45 ft 11 in
- Square-foot density
- Not suited to SFG
- Root system
- Woody, with a taproot it keeps
- Working depth
- 24 in–5 ft
- Can reach
- 10 ft down where the soil allows
- Spread
- 69–115 ft across, about 1.5–2.5× the width of the plant
It anchors downwards as well as sideways, which is what lets it stand in a gale and what makes it hate being moved. Plant it small: past a few years in the ground a taprooted tree transplants badly, and often not at all.
Deep-rooted, which makes it a good street tree, and inclined to sucker from the roots, which makes it a poor lawn one. The suckers come up some way out.
The habit is Kentucky coffeetree’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- When
- Not harvested. Rake or leave the pods from female trees in late fall; prune in winter while young.
- What to look for
- The big leathery pods drop after leaf-fall and lie about all winter.
- How to harvest
- Rake pods off lawn and paths (they are toxic raw, and heavy enough to matter under a mower). Structural pruning in the first decade sets the tree up; after that it wants nothing.
- How often
- One pod cleanup a year under a female; none at all under a male cultivar.
- Storing the crop
- Nothing to store. Despite the name, do not roast your own: the settlers' coffee substitute required exact roasting to be safe, and the beans are toxic until then.
- Generally trouble-free No notable pest or disease problems when grown in the right conditions — one of the easy ones.
Settlers roasted the seeds as a coffee substitute, which is as far as the resemblance goes; the raw pods and seeds are toxic. Plant a male ('Espresso') to skip the pods entirely. It leafs out last of all and drops first, which its sparse winter silhouette makes into a virtue.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com