The Japanese barberry is a spiny shrub that produces brown, deeply grooved branches that are spiny and grow in a zig-zag pattern. The bluish-green, small leaves grow from 1/2 inch to 1 1/2 inches long and are oval. The leaves are also can be dark reddish-purple. The Japanese barberry produces pale yellow flowers from mid-April to May that hang in clusters of two to four flowers.
The Japanese barberry (Berberis thunbergii) was introduced to the United States in 1875 through seeds sent from Russia to the Arnold Arboretum in Boston, Massachusetts. The seeds were planted in 1896 at the New York Botanic Garden. Common barberry (Berberis vulgaris) was used by settlers for dye, jam and hedgerows. The Japanese barberry was soon used as a substitute for common barberry, which was highly susceptible to black stem grain rust. Many cultivars were propagated using the plants from the original seeds.
Though the Japanese barberry is drought resistant, water it with at least an inch of water per week for healthier plants. The soil should be kept moist, but not drenched. If you have a problem with standing water in the location of the barberry, create French drains to remove the excess.
The Japanese barberry is propagated mainly through its seeds, which it produces in high numbers. The seeds have a high germination rate--up to 90 percent. Birds and other animals transport the barberry seed to different locations. Cuttings are also used to propagate the barberry. If branches touch the ground, they will root and form new plants. Root fragments will also create new plants.
Because the Japanese barberry propagates easily, it forms dense colonies in most habitats, including open woodlands, wetlands, meadows, canopy forests and pastures. The Japanese barberry is so dense that it robs the soil of nitrogen levels and changes its pH. It is deer resistant, so it is not kept in check by browsing, giving it a large advantage over native growth. It is considered an invasive plant in the District of Columbia and 20 states, though it is still propagated and sold by nurseries throughout the U.S.
Removal and Control
There are several ways to control Japanese barberry besides not planting it. If you notice Japanese barberry on your property or should decide to plant it in a limited area, keep it in check by pulling excess plants and the entire rootball. If the barberry becomes an infestation, there are chemical treatments (Roundup, Garlon) that are effective. The tree can also be removed using a hoe or other tools. A Weed Wrench can be used to uproot larger or older shrubs that have taken a stronger hold. Remove the Japanese barberry in late summer, before seed production.