Common Name: Japanese white birch
Type: Tree
Family: Betulaceae
Native Range: Manchuria, Korea, Japan
Zone: 4 to 7
Height: 30.00 to 40.00 feet
Spread: 15.00 to 25.00 feet
Bloom Time: March to April
Bloom Description: Yellowish-brown (male) and green (female)
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: High
Flower: Showy
Other: Winter Interest
Tolerate: Deer
Culture
In St. Louis, this white birch is best grown in medium to wet, well-drained, sandy or rocky loams in full sun to part shade. Although it prefers full sun in its native habitat, in St. Louis, it is best sited in a northern or eastern exposure that receives some afternoon shade. It needs consistently moist soils. Consider using soaker hoses and bark mulches to keep the root zones cool and moist. It needs little pruning, but if necessary, prune during the dormant season. Avoid pruning in spring when the sap is running. Performs best in cool northern climates where summer temperatures rarely exceed 75 degrees F. and where root zones are generally covered with snow throughout the winter.
Noteworthy Characteristics
Betula platyphylla, commonly called white birch or sometimes Asian white birch, is native to Manchuria, Korea and Japan. It is closely related to B. pendula. It is a medium to large sized tree that typically grows to 30-40’ (less frequently to 70’) tall with a pyramidal habit. This tree is noted for its white bark, thin spreading branches and slightly pendant branchlets. Ovate, glabrous, toothed, yellowish-green leaves (to 3” long) have tapered tips. Fall color is usually undistinguished. Tiny monoecious flowers appear in early spring in separate catkins on the same tree: yellowish-brown male flowers in drooping catkins (to 3” long) and greenish female flowers in smaller, upright catkins (to 1 1/4” long). Female flowers are followed by drooping cone-like fruits containing numerous small winged seeds that typically mature in late summer. Young twigs have resinous glands.
Genus name is the Latin name for birch.
Specific epithet means broad-leaved.
Problems
This species of birch grows poorly and is generally short-lived in the St. Louis climate. It thrives in cool northern summers, but does poorly in the heat and humidity of St. Louis. Weakened birches become very vulnerable to the bronze birch borer which, in the St. Louis area, typically attack and kills trees that are stressed by summer heat and humidity. This tree reportedly has some resistance to the borer. Although white birches have some susceptibility to aphids, birch leaf miner, birch skeletonizer and dieback, these problems are usually considered to be somewhat minor in comparison to the birch borer. Plants stressed by insects seem more susceptible to cankers.
Uses
Not recommended for the St. Louis climate. River birch (see Betula nigra) is a better selection for St. Louis. In cool northern climates, this white birch is an excellent landscape tree that displays a graceful form and mixes well with evergreens.