Japanese barberry (Berberis thunbergii) commonly is grown as an ornamental shrub in garden settings, particularly where other shrubs tend to fail. The barberry's foliage is used for color contrast among other plants as well to provide bright fall color in tones of yellow, orange and scarlet. Be warned that in some regions, this species is regarded as a noxious weed or prohibited plant since its yellow flowers produce copious seeds and the roots sprout suckering shoots. Grow Japanese barberry in USDA zones 5 through 8.
The natural leaf color of the Japanese barberry is medium green with hints of blue-green, according to the American Horticultural Society's "A-Z Encyclopedia of Garden Plants." Moreover, the other species of barberry typically bear green foliage that is either evergreen or deciduous, often attaining shades of red, orange or yellow before the leaves drop off in fall. From an ornamental standpoint, green-leaved Japanese barberry is not usually grown by gardeners, although the thorny stems and tough disposition of the shrubs do lend themselves for use as simple hedges or low-maintenance foundation shrubs. Cultivars "Kobold" and "Globe" produce nicely shaped plants with medium, lush green hues.
Horticulturists noted that some seedlings of Japanese barberry shrubs developed lighter green to yellow or chartreuse foliage; these were selected and propagated and given cultivar names. "Aurea" develops new foliage that is particularly yellow in color before maturing to a light yellowish green. A dwarf form of this plant is known as "Aurea Nana." Other examples of cultivars with varying degrees of gold and yellowish to chartreuse leaves are "Sunjoy Gold Beret," "Sunsation," "Sunjoy Gold Pillar" and "Lime Glow."
A naturally occurring form (atropurpurea) of Japanese barberry exists, and is often more widely utilized for its reddish green or red-purple/burgundy colored foliage in gardens. Many cultivars have been selected and named, having different plant forms as well as their depths of red, purple or burgundy leaf colors during the growing season. Red-hued Japanese barberries include "Bagatelle," "Crimson Pygmy," "Dart's Red Lady," "Helmond Pillar," "Atropurpurea Nana," "Red Pillar," "Royal Cloak" and "Rose Glow." Variation occurs among these cultivars in the foliage, as some produce lighter colored new growth or tend to retain the purplish pigments better across the heat of summer.
Variegation refers to multiple colors in the foliage. Two examples of Japanese barberries with variegated leaves are "Golden Ring" (purple leaves edged thinly in golden yellow) and "Silver Beauty" (leaves mottled in creamy white). "Pink Queen" produces new springtime leaves that are heavily veined and variegated with pink, white and red while "Rose Glow" has new leaves that are solid red-purple but tend to mature with white flecks.