Yes, Japanese barberry (Berberis thunbergii) is an invasive plant. If that tilts your world a little, don’t feel alone. This longtime landscaping favorite is everywhere, from arboretums to nurseries to your neighbor’s yard. Hybridizers are even working on new barberry cultivars as you read this. Yet it’s true: Japanese barberry—a mid-sized shrub with arching branches, red berries, nasty spines, and red-purple, green, or gold foliage—is invasive.
This aggressive deciduous shrub has invaded woodlands, wetlands, and meadows in at least 20 states in the United States. It threatens native plants as well as the wildlife that depends on those plants. Barberry is a triple threat because it spreads by roots, seeds (which are carried for miles when birds eat the berries), and branches (which can root where they touch the ground). The bushes form a spiny thicket that even deer leave alone, in favor of more tender native plants, giving barberry yet another advantage.
Don’t plant Japanese barberry. Instead plant more well-behaved dark-foliage plants such as Summer Wine or Coppertina ninebark, burgundy-leaved weigelas, or Black Lace or Black Beauty elderberry. Dig up small barberry plants (ones up to 3 feet tall) by hand or mow them down before they set fruit. Cut down larger plants or use a systemic herbicide like glyphosate or triclopyr on them, following package directions. Be careful not to splash the herbicide on nearby plants.
— photo of Berberis thunbergii courtesy of Missouri Botanical Garden’s Kemper Center for Home Gardening