'Nigra' Bigleaf Hydrangea |
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Botanical Name: Hydrangea macrophylla (Thunb.) Ser. 'Nigra' Family: Hydrangeaceae Hardiness: U.S.D.A. Zone 6. Development The U.S. National Arboretum is a modern-day leader in the collection and conservation of landscape plants. In a 1985 expedition to Japan, Hydrangea 'Nigra' was identified as a plant with potential for American gardens and purchased by S. March, U.S.N.A., and F. P. Darke, Longwood Gardens, from Kenji Watanabe, Gotemba Nursery, Gotemba, Shizuoka Prefecture, Japan. Hydrangea 'Nigra' has been in cultivation in England since the late 1800's. Following 8 years of landscape and garden evaluation in the U.S., 'Nigra' was released to the American nursery trade through cooperating growers in 1993. (Syn.: H. macrophylla 'Mandshurica'). Significance: This cultivar is noted for the blackish purple color of the juvenile stems. Hydrangea 'Nigra' received a First Class Certificate in 1895 and an Award of Garden Merit in 1993 from the Royal Horticultural Society of Great Britain. Description: Height and Width: To 6.0 feet in height and width. Habit: Strongly branched deciduous shrub. Foliage: Broadly ovate leaves 4-6 inches long and 2.75-4 inches wide with coarse serrations, yellowish to fresh green in color. Bark: Stem color of new growth blackish purple making a striking contrast to the leaves. Flowers: Inflorescence is a large, branched globose cyme of the hortensia or mop-head type with abundant, mostly sterile, individual florets, 4-5 petal-like sepals per flower. Flower color blue or rose-pink depending on soil pH. Plants flower from buds formed during the previous season's growth (old wood). Culture: Hydrangea macrophylla grows best in moist, well-drained soil, in full sun to partial shade. In the Washington, DC, area, 'Nigra' seems to perform best in moist soil under light shade. Prune immediately after flowering. Flower color is blue in acid soil and rose-pink in a neutral or slightly alkaline soil. Propagation: Roots easily from stem or leaf-bud cuttings, taken in late spring through mid-summer, under mist, 1000 ppm IBA, in 3-5 weeks. Will root from cuttings taken at most times of the year. Landscape Use: Highly attractive as a pot plant or summer flowering shrub in the garden border in sun or partial shade. Source: U.S. National Arboretum |