Barberries are often used in the southern landscape because they tolerate extreme soil and climate conditions and require minimum maintenance.
The species most often found in South Carolina are wintergreen barberry, Mentor barberry and Japanese barberry.
Japanese Barberry: Japanese barberry (Berberis thunbergii) is the most popular landscape barberry. Many cultivars are available. It grows from 3 to 6 feet tall and 4 to 7 feet wide, depending on the cultivar. The shrub is medium to very dense with many thorns. The leaves are bright green in summer, changing to orange, scarlet and reddish purple in the fall. Japanese barberry is deciduous, and it is one of the first shrubs to leaf out in spring. This is true for most of the deciduous barberries. The yellow flowers in spring are not very showy, because they are small and borne under the foliage, but the berries are bright red in the fall. The ½-inch berries persist into winter and make an excellent winter effect.
Wintergreen Barberry: Wintergreen barberry (Berberis julianae) is an evergreen shrub with thorny branches. It grows about 10 feet tall and wide. The thorns and dense growth habit combine to make this an excellent barrier plant. The leaves are a lustrous dark green. They turn bronze or wine-red in the fall and remain so during the winter. Abundant yellow flowers in spring are followed by bluish-black, 1/3-inch, oval fruits that may persist into fall.
Mentor Barberry: Mentor barberry (Berberis x mentorensis) grows 4 to 6 feet tall and 5 to 7 feet wide. It loses its leaves in winter, but may be semi-evergreen in warm areas. The dark green, leathery leaves turn orange to red in the fall. The yellow flowers in spring are not as showy as the flowers of other species, but they are still attractive. Mentor barberry does not produce any fruits.
Japanese Barberry: The growth rate of Japanese barberry is medium, 1 to 2 feet per year.
Wintergreen Barberry: Wintergreen barberry grows slow, 12 to 18 inches per year.
Mentor Barberry: Mentor barberry grows much faster, at a rate of 2 feet per year.
All barberries make excellent hedge plants because of their uniform growth rate, and they make excellent barrier plants because of the thorny nature of their stems. They can be used for massing, shrub borders and as foundation plants. Japanese barberry is often used to hold and furnish slopes and banks.
Barberries prefer sun or partial shade. They are tolerant of most soil types and withstand dry conditions. They tolerate urban conditions better than many shrubs.
Barberries transplant easily and withstand pruning well. This is best done immediately after flowering or in later winter.
Except with formal hedges that need shearing one or more times a year, pruning should be kept to a minimum. Shrubs that become overgrown may be revitalized by cutting them back very severely, even to within a foot or so of the ground, in late winter. Fertilize the shrubs in spring.
Normally, barberries are not seriously affected by diseases and insects. They are occasionally subject to:
- Anthracnose, a fungal disease that manifests itself as round, brown spots with reddish margins on the upper leaf surface;
- Powdery mildew, a fungal disease that causes a white coating on the leaves;
- Phyllosticta leaf spot, which causes purple spots on the leaves.
Insects that sometimes infest barberries are:
- Aphids, which suck plant juices and coat the leaves with sticky honeydew.
- Scale insects, which can be controlled by applying dormant horticultural oil in the spring before growth begins, or with labeled pesticides when the crawlers are active. Crawlers are the immature forms that hatch from the eggs. They are not protected by a scale like the adults.
- The barberry webworm, which is a small black caterpillar with white spots that ties together the leaves and shoot tips.
Cultivars & Varieties
Cultivars of Japanese Barberry: There are many cultivars available. Some of the more common ones are:
- var. atropurpurea – The leaves assume reddish to purplish shades. The yellow flowers are tinged with purple, but the fruits are the same bright red as those of the species.
- var. atropurpurea ‘Crimson Pygmy’ – This is the most popular Japanese barberry selection. This low, dense plant grows to 2 feet tall and 3 feet wide. The foliage color is best when grown in full sun.
- var. atropurpurea ‘Rose Glow’ – The new leaves are rose-pink, mottled with deeper red-purple splotches. The colors gradually mature to a deep reddish purple. This variety has become extremely popular in the South. It grows to about 6 feet tall.
- ‘Aurea’ – The leaves of this dense, relatively slow-growing shrub are bright yellow. It does not flower or fruit heavily.
- ‘Kobold’ – Its habit is similar to that of a compact Japanese holly or boxwood. The shrub grows to 2 feet at maturity and forms a perfect mound without pruning.
Cultivars of Wintergreen Barberry:
- ‘Nana’ grows to 4 feet high and forms a solid mound. The glossy, dark green leaves turn wine-red in winter. It has large spines.
- ‘Spring Glory’ is a selection with brilliant coloration to the new shoot growth. The leaves and stems are tinted red to bronze-red. Pruning this shrub is not recommended.