Common buckthorn is an invasive plant in Illinois and should not be planted. It forms dense thickets and reproduces very freely, crowding out other plants and disrupting ecosystems in forest preserves and other natural areas. In woodlands it can completely replace existing understory plants, including native wildflowers. Buckthorn has berries that are spread by birds. The seeds germinate at a very high rate and remain viable in soil for two to three years. Buckthorn is very common in gardens and yards in the Midwest, but should be removed where it is found. Buckthorn is a large shrub or tall tree with glossy oval leaves that can easily be recognized in fall, when it remains green after most other leaves have fallen. Under the Illinois Exotic Weed Act, buckthorn cannot be sold in Illinois.
- Deciduous (seasonally loses leaves)
- Small tree (15-25 feet),
- Compact tree (10-15 feet),
- Large shrub (more than 8 feet)
- Full sun (6 hrs direct light daily),
- Partial sun/shade (4-6 hrs light daily),
- Full shade (4 hrs or less of light daily)
- Zone 3,
- Zone 4,
- Zone 5 (Chicago),
- Zone 6,
- Zone 7
- Acid soil,
- Alkaline soil,
- Dry soil,
- Moist, well-drained soil,
- Wet soil
Tree & Plant Care
This is an invasive plant. Do not plant it.
However, if the plant is already persisting, there are several management methods. The buckthorn can be managed culturally by pulling small plants and seedlings or mowing them over. Large plants can be girdled by removing 2 inch strips of bark from each stem and applying herbicide to the girdled surface. The buckthorn can also be controlled chemically in late fall. Systemic chemicals can be sprayed on the plant to be drawn down into the plant’s roots. Furthermore, a stump treatment can be implemented by using glyphosate or triclopyr paint or spray on a freshly cut stump.
Disease, pests, and problems
Buckthorn is susceptible to rust and powdery mildew.
Buckthorn is on Illinois’ exotic weed list due to its high germination rate in a variety of habitats including gardens, fence rows, pastures, prairies, and abandoned farm fields. In woodlands it can completely replace existing understory plants; including native wildflowers. Seeds remain viable in soil for 2 to 3 years which contributes to the invasive nature of this plant.
Native geographic location and habitat
Bark color and texture
The tree’s bark is brown to gray in youth, rough and peeling with prominent whitish lenticels and yellow coloration on the inside. The stems may form dense thickets.
Leaf or needle arrangement, size, shape, and texture
Leaves are opposite to sub-opposite; 1 ½ to 3” long and ¾ to 1 ½” wide; elliptical in shape with minute teeth on margins, rounded to pointed tips. Remain bright green in fall for some weeks after most other shrubs and trees have lost their leaves.
Flower arrangement, shape, and size
Male and female flower on separate plants (dioecious). The flowers are small, green and fairly inconspicuous.
Fruit, cone, nut, and seed descriptions
Berry-like fruits are in clusters on female plants only. They are dark blue in late spring and early summer, turn black in August and persist throughout the winter.