If invasive species are considered the evil thugs of the plant world, then buckthorn is one of the worst offenders. When it first arrived from Europe in the 1800's, buckthorn was heralded as the ideal shrub plant for creating hedges. That all changed a short while later when it began to plunder its way through our natural areas. If buckthorn is bullying the plants in your yard, getting rid of it without chemicals won't be easy, but it can be done.
Like all invasive species, buckthorn lacks the natural controls (e.g. insects, disease) that normally work to keep native plant populations in check. It's also one of the first plants to leaf out and one of the last to drop its leaves. As a result, it's able to out-compete nearby plants for food, water, and light, and quickly takes over surrounding areas.
Buckthorn is spread by birds that eat and scatter its berries. When you consider that every one of the plant's berries contains 3-4 seeds, each of which can remain viable in the soil for up to 6 years, it's easy to see why buckthorn has become such a widespread problem!
Several species are commonly mistaken for buckthorn, so it's important to make sure you have identified it correctly before you try to remove it. The two types buckthorn that are considered invasive are Common Buckthorn (Rhamnus cathartica) and Glossy Buckthorn (Frangula alnus).
Common Buckthron (Rhamnus cathartica)
Glossy Buckthorn (Frangula alnus)
Try killing young seedlings (4.5 cm or less) with a flame torch. Small shrubs (3/8 inch diameter or less) do not have deep roots and can be hand-pulled or removed with a hoe. Wetting down the soil beforehand or waiting until it rains will make the job easier.
Glossy buckthorn can be girdled (and eventually killed) by cutting a 3 cm strip through the bark around the entire base of the trunk. Girdling is a great option because it doesn't disrupt nearby soil, it will not cause the shrub to re-sprout, and can be done any time of the year.
Large shrubs (greater than 2 inches) should be cut as close to the ground as possible using a handsaw, and if possible, the entire stump removed. Plant the exposed soil immediately with a native tree or shrub.
If removing the stump isn't possible, repeated cutting and removal of the resulting suckers will eventually kill the shrub. This will take time so don't give up!
Shrubs that have been removed should be burned or hauled away (as waste refuse) to prevent seeds from sprouting somewhere else.