Zanthoxylum americanum
northern prickly ash
Attracts PollinatorsAttracts ButterfliesDeer ResistantDrought TolerantFragrant (moderate)
Native to North America
Overview
Zanthoxylum americanum is a deciduous, suckering shrub or small tree in the citrus family, reaching 10-25 feet (3-7.6 m) tall and forming dense, thicket-like colonies. The stems and branches bear paired, sharp prickles, and the pinnately compound leaves, 5-10 inches (13-25 cm) long with 5 to 11 leaflets, release a citrus-like scent when crushed. It is dioecious, with separate male and female plants; in early spring, before or as the leaves emerge, both sexes produce small clusters of tiny yellow-green flowers along the previous year's twigs. Female plants follow with clusters of small red, pitted fruits that split to reveal shiny black seeds, both aromatic and pungent. Native to central and eastern North America, it grows in woods, thickets, fencerows, and along streams on a range of soils. Z. americanum tolerates shade, varied soils, and cold, but its prickly stems and strong suckering make it spread into broad colonies that are hard to contain. Chewing the bark or fruit produces a numbing, tingling sensation, the source of the name toothache tree.
Native Range
Native to central and eastern North America, from Quebec and Ontario south to Georgia and west to the Great Plains. It grows in woodlands, thickets, fencerows, and streambanks on a wide range of soils.Suggested Uses
Used in naturalized plantings, wildlife and butterfly gardens, hedgerows, and erosion control on banks, where its suckering habit forms a dense thicket. As a host for the giant swallowtail and a nectar and fruit source, it suits habitat-focused plantings, spaced 6-10 feet (1.8-3 m) apart or allowed to colonize. Its prickly stems also make it a barrier or security planting.How to Identify
Appearance
Size & Dimensions
Height10' - 25'
Width/Spread10' - 20'
Reaches mature size in approximately 7 years
Bloom Information
Flowering occurs in early spring, generally April to May, before or just as the leaves unfold. The small yellow-green flowers form tight clusters along the older wood and are easy to overlook. Male and female flowers are on separate plants, so only female plants set the red fruit that ripens in late summer.
Detailed Descriptions
Foliage Description
greenGrowing Conditions
Sun Requirements
Requires 4-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Grow Z. americanum in full sun to partial shade in moist, well-drained soil, though it adapts to dry and poor ground. It is cold-hardy and needs little care once established. It spreads aggressively by root suckers, so it forms wide colonies unless the suckers are removed. Both male and female plants are needed for fruit. The sharp prickles make handling and pruning difficult. It has few serious pests and serves as a larval host for the giant swallowtail butterfly.Pruning
Pruning is done in late winter while dormant, cutting out crowded or damaged stems and removing root suckers to limit the colony. The prickles make pruning slow, and protective gloves reduce injury from the spines. The plant resprouts readily from cut stumps and roots.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
winter