Grow prickly ash in full sun to part sun, in soil that drains. Prickly ash is Zanthoxylum americanum, also called common pricklyash and toothache tree — a deciduous citrus-family shrub that spreads by suckers and paired prickles, not a true ash and not a Sichuan-pepper crop.
Give it full sun to part sun, and soil that drains
| Factor | Recommended | Avoid |
|---|---|---|
| Light | Full sun to part sun | Do not site it in deep shade if you want flowers and fruit |
| Soil | Average soil that drains; it takes clay, rock, and a short wet spell | Do not leave the roots in a stagnant hole, and do not plant it on a walk |
| Water | Water through the first year; once established it takes a dry spell | Do not treat a new planting as drought-proof |
| Size | About 15 to 20 feet as a shrub or small tree, spreading by suckers | Do not plant it where people have to brush past the prickles |
prickly ash is a deciduous suckering shrub about 15 to 20 feet tall, with paired prickles on the twigs and often on the leaf stalk. Sit it in full sun to part sun on soil that drains. It takes clay, rock, and a short wet spell as long as water still moves. Keep a new planting watered through the first season. After that, a short dry spell is not a crisis, but a brand-new plant is not drought-proof. [1] Crush a leaflet and it smells like lemon peel. Small yellowish-green flowers open in spring before the leaves, on separate male and female plants, so you need both if you want fruit. Deep shade may skip the flowers. Giant swallowtail caterpillars use the foliage; that is a host, not a reason to spray.
How much sun does prickly ash need?
Full sun to part sun. Deep shade may skip the flowers and fruit. A short dry spell is fine once the plant is established, but water it through the first year.
Plant it as a barrier, with gloves and room to sucker
Wear gloves and long sleeves. Set a nursery plant in spring or in early fall, in a full-sun to part-sun strip you can let thicken as a hedge or a screen — not a path. Slide it out of the pot and plant it at the same depth it grew. Give it several feet of room, because the roots run and send up new stems. If the thicket has to stop at a walk, set an edge before you plant. [2] Firm the backfill so there are no air pockets, water it in the same day, and keep the soil from going bone-dry through that first season. Do not dig plants from the woods.
- Wear gloves and long sleeves before you handle the stems.
- Pick a full-sun to part-sun strip you can let thicken as a hedge or a screen, not a path.
- Plant in spring or early fall, at the same depth the plant grew in the pot.
- Give it several feet of room, or set an edge first so suckers cannot cross a walk.
- Water thoroughly the same day, and keep the soil from going bone-dry through the first growing season.
How do I plant a nursery prickly ash?
Wear gloves. Plant it in spring or early fall, at the same depth it grew in the pot, in full sun to part sun. Give it several feet of room or set an edge first, water the same day, and keep it from drying out the first year.
Start more plants from a sucker, a root cutting, or fall-sown seed
If the colony has filled, lift a rooted sucker in late winter or very early spring, before the leaves fill. Each piece needs some root and a bud that can send up a stem. Replant it the same day at the same depth, in sun that drains, and water it in. A short section of root, laid in soil that drains and kept moist, also sends up new shoots. Fresh seed is the other route: pick the capsules when they split in late summer, and sow the shiny black seed in fall as soon as you collect it. Stored seed needs a long winter chill in moist sand before spring sowing. [3] Division from a sucker is how most garden plants are raised; seed is slower and uneven.
- Wait until late winter or very early spring, on a colony that can spare a piece.
- Lift a rooted sucker, or cut a short section of root that has a bud, and replant it the same day.
- Or sow fresh seed in fall as soon as the capsules split; keep stored seed in moist sand through winter if you missed that window.
- Water new pieces in, and leave them alone while they settle, keeping the soil from going dry.
How do I start more prickly ash plants?
Lift a rooted sucker in late winter, or lay a short piece of root in soil that drains. Fresh seed can go in the ground in fall as soon as the capsules split. Water new plants and keep them from drying out while they settle.
Not an ash tree — and not Sichuan pepper
True ash is a different tree. Ash has opposite compound leaves; prickly ash has alternate leaves and paired prickles, and it belongs with citrus, not with ash. If the tag says Fraxinus, see How to Grow Ash Trees. Sichuan pepper in the spice aisle is usually Japanese pepper or a Chinese Zanthoxylum grown for the husks, not this northern native. Do not harvest this shrub as a pepper crop. If you wanted a pepper vine, see How to Grow Black Pepper. Garden peppers are Capsicum — see How to Grow Peppers if that is the plant. [4] Southern toothache tree, also called Hercules club, is Zanthoxylum clava-herculis, a coastal tree with corky knobs on the trunk and larger clusters of fruit. Devil's walking stick is Aralia, another spiny native with a different leaf; see How to Grow Aralia if the tag is an aralia. A young black locust also has prickles and pinnate leaves, but it becomes a much larger tree — see How to Grow Black Locust. Hardy orange is another thorny citrus relative for a barrier; see How to Grow Hardy Orange. Hop tree, sometimes sold as wafer ash, is Ptelea, a citrus relative without this shrub's paired prickles; see How to Grow Hop Tree if that is the tag. Grocery citrus wants a different winter and a different fruit job; see How to Grow Citrus if you wanted an orange or a lemon.
Is prickly ash a true ash?
No. True ash is Fraxinus, with opposite compound leaves. Prickly ash is a citrus-family shrub with alternate leaves and paired prickles.
Is prickly ash the same as Sichuan pepper?
No. Sichuan pepper in the kitchen is usually a different Zanthoxylum grown for the husks. This northern native is a thorny thicket, not that spice crop.
If suckers cross a walk, set an edge and wear gloves before you cut them. Keep a new plant watered through its first year, and confirm the tag is Zanthoxylum americanum, not an ash tree and not a pepper crop.
FAQ
Is there more than one kind of prickly ash?
Zanthoxylum americanum is the shop plant. Common pricklyash and toothache tree are names for the same shrub, not extra kinds. Sichuan pepper and southern Hercules club are other species.
Can I grow it in a pot?
A wide pot of mix that drains can hold a young plant for a season, but this is a suckering shrub that wants room to thicken. It is not a houseplant. Keep the mix from sitting in a saucer of water.
Will it come back after winter?
Yes. It is a hardy deciduous shrub. The stems stay, the leaves drop, and you do not lift it. A thin leaf mulch is enough.
Do I need to prune it?
No yearly hedge shear. Cut a stem only if it pokes a walk, and wear gloves. Leave a healthy thicket alone.
Can I use the bark for a toothache?
Grow it as a barrier and a wildlife thicket, not as a home remedy. Do not chew the bark, and do not dig wild stands for medicine.
Recommended plants
References
- [1] The Morton Arboretum -
https://mortonarb.org/plant-and-protect/trees-and-plants/prickly-ash/ - [2] NRCS Plant Guide -
https://plants.sc.egov.usda.gov/DocumentLibrary/plantguide/pdf/cs_zaam.pdf - [3] Lady Bird Johnson Wildflower Center -
https://www.wildflower.org/plants/result.php?id_plant=ZAAM - [4] Illinois Wildflowers -
https://www.illinoiswildflowers.info/trees/plants/prickly_ash.html
More first-season notes by plant are gathered in How to Grow Guides.
Updated: Reviewed by Bosquelle Editors