Japanese Gray Birch Betula populifolia 'Whitespire'

Betula is Latin for birch and describes a genus of about 60 species of deciduous trees and shrubs found in many gardens and landscapes throughout the northern hemisphere. The species, Betula populifolia, or gray birch, is a short-lived, narrow-columnar, suckering, deciduous tree that typically grows to 20-40’ tall. The species is noted for its non-peeling chalky white bark and its long-pointed triangular green leaves. Tiny monoecious flowers appear in early spring in separate catkins on the same tree: yellowish-brown male flowers in single catkins (to 4” long) at the branch tips and greenish female flowers in smaller, upright catkins (to 1/2” long).

The cultivar, 'Whitespire', is best known for its upright form, non-exfoliating white bark, dark green leaves and attractive yellow fall color. This plant has many benefits including ease of transplant, that it casts light shade, and tolerates heat, wind, deer, and drought. However, it does not tolerate dry soils and has shallow roots. It will self-seed and form an attractive stand of trees. Vegetatively propagated plants of this cultivar are considered to have better resistance to bronze birch borer than seed propagated plants, resulting in the use of the cultivar name 'Whitespire Senior' by some nurseries as a way of designating those plants which have been vegetatively propagated. 'Whitespire' was originally named as a cultivar of Betula platyphylla var. japonica when introduced into commerce in 1983, but that designation was subsequently changed when it was determined 'Whitespire' was in fact a gray birch.

Japanese Gray Birch grows best in medium to wet, well-drained, sandy or rocky loams in full sun to part shade. It seems to tolerate drier soils in its native range. It also tolerates poor soils. Keep the root zones cool and moist and consider using soaker hoses and bark mulches. The plant performs best in cool northern climates where summer temperatures rarely exceed 75 degrees F. and where shallow root systems are generally covered with snow throughout the winter. In optimum growing conditions, plants will easily spread by suckers. It needs little pruning, but if necessary, you can prune during the dormant season. Do not prune in winter or spring when the sap is running because it will bleed. Birches are considered a "pioneer" species and, thus, tends to grow quickly when young.

Diseases, Insects, and Other Plant Problems:

This cultivar can become stressed by summer heat and humidity. It is not recommended for planting south of USDA Zone 7. Unlike many varieties of Birch, the Japanese Gray Birch is somewhat resistant to bronze birch borer.  However, it is susceptible to leaf miner. Watch for leaf spot problems. Although this gray birch has some susceptibility to aphids, birch skeletonizer and dieback, these problems are usually considered to be somewhat minor in comparison to the birch borer and birch leaf miner. Plants stressed by insects seem more susceptible to cankers.