Culture
Easily grown in average, dry to medium, well-drained soil in full sun. Tolerates part shade, but performs best with full sun. This is a very adaptable shrub that is tolerant of urban conditions. Plants also tolerates heat and drought, but are generally intolerant of poorly-drained, wet soils. Plants spread slowly by creeping roots. Plants can also spread by self-seeding (birds will eat the fruits and distribute the seed). Plant branches may root where they touch the ground. This species is considered to be highly invasive in some areas (particularly in eastern North America).
'Kobold' is reportedly a sterile cultivar that will not self-seed. Plants typically form an attractive mound without pruning. Propagate from cuttings.
Noteworthy Characteristics
Berberis thunbergii, commonly called Japanese barberry, is a spiny, broad-rounded, deciduous shrub with obovate green leaves. It typically matures to 5' tall and as wide. Leaves (variably sized to 1 1/4” long) typically turn attractive shades of orange, yellow and red in fall.
Genus name comes from the Latinized form of the Arabian name for the fruit.
Specific epithet honors Swedish botanist Carl Peter Thunberg (1743-1828) who reportedly identified this species in Japan in 1784.
‘Kobold’ is a dense, compact, low-mounding cultivar that typically matures to only 2' tall and as wide. It is typically grown for its attractive foliage and symmetrical compact size. Leaves emerge bright green in spring and mature to glossy dark green in summer before eventually turning pale yellow (sometimes tinted with red) in fall. Tiny, bell-shaped, pale yellow flowers (to 1/2” long) may bloom in short racemes in March-April along the stems, but flowering for this cultivar is uncommon. Flowers that do occur may be followed by glossy, ellipsoid, bright red berries that mature in fall and persist into winter. Stems are clad with small spines. 'Kobold' was introduced into commerce by Van Klavern of Boskoop, Holland around 1960. U.S. Plant Patent PP3,038 (now expired) was issued in 1971.
Problems
No serious pest problems. Some susceptibility to bacterial leaf spot, anthracnose, root rots, wilt, aphids, barberry webworm and scale. Spiny stems often trap unsightly wind-blown trash. Deer resistant. This species is known to be highly invasive in portions of the eastern United States, spreading readily by bird-dispersed seeds and forming impenetrable thickets which leaf out before native understory species, shading out wildflowers and other native plants.
Uses
Accent for small areas in the landscape. Foundations. Shrub border. Hedge or edger. Spiny barrier plant.
Edging or small hedge.