Buckthorn is an invasive understory shrub or small tree that forms a dense canopy and can grow up to 20-feet tall. It out-competes native plants for light and nutrients and becomes the sole, dominant survivor.
How to identify
Buckthorn is easily identified in the fall after many native shrubs and trees have lost their leaves. You can often see it growing under the canopy of overstory trees. It is a dense, green thicket. There are two types:
- Common buckthorn: Thrives in dry to moist areas and grows in full sun to shade. The oval dark green leaves have fine toothed edges. There is a sharp thorn at the tip of the twig. The leaves stay on late into the fall which makes that a good time to find it. However, it is easily confused with native cherry, plum, and dogwood. The female plant has berries that turn from green to black.
- Glossy buckthorn: Thrives in wet areas but will cultivate in dry land. It grows in both sun and shade. The oval, dark green leaves are glossy with toothless edges. Berries on the female plant turn from reddish-brown to black. For more detail,
Why is buckthorn a problem?
This highly invasive plant will take over areas, and it may even be in your yard. Buckthorn chokes out native plants and degrades ecosystems. Buckthorn has no controls. There is no disease or insect in Minnesota that will keep it in check. Because of that, it spreads quickly. Birds will eat the berries, which are a diuretic, and then spread the seeds.
Dense foliage helps it mature quickly. Buckthorn does not allow native plants to regenerate and grow. If left unchecked, it can destroy wooded areas. Buckthorn is also a threat to prairies, wetlands, rivers, and lakes. It forms dense thickets in forests, parks, and roadsides and by streams and rivers. It produces a chemical called immoden that doesn't allow other plants to grow near it. With that, it destroys the habitats of animals and amphibians.
How to control buckthorn
- If the soil is moist, small plants can be pulled, as long as the roots come out. Be sure to tap off the soil from the roots.
- Slightly larger plants can be pulled using a weed puller. You can borrow a weed puller from the City of Maple Grove. Call engineering staff at 763-494-6361 to reserve.
- For larger plants or when the soil is dry, buckthorn can be cut. Immediately after cutting, an herbicide must be applied to the cut stump. This will prevent resprouting. If this is not done, the plant will resprout with many shoots coming off the stump.
- For non-chemical control, a cut stump can be covered with a tin can (nailed in) or black plastic (zip tied on) and left for one to two years.
- Return to the area yearly to control small plants as they sprout.
- Leave pulled or cut buckthorn on the site, place it in your yard waste, or bring it to the Maple Grove Yardwaste Site.
- In the areas where buckthorn is heavy, once it's removed and native species don't come back, you may need to plant some native plants, such as chokecherry, hazelnut, dogwood, nannyberry, and high-bush cranberry. Local garden centers also may have suggestions.