Evergreen shrubs provide color and textured interest during the winter months. Both boxwood (Buxus spp.) and wintergreen (Gaultheria spp.) display small, oval, broadleaf foliage, not needles as in the case of conifer evergreens. Both of these woody, temperate-zone shrub types are used for edging or billowing groundcovers in American gardens. The taxonomy within the genus Buxus is muddled and confusing, as species names and genetic identity of many of the boxwood cultivars vary. To confound the discussion, there is a boxwood shrub cultivar named Wintergreen.
Shrubs colloquially known as wintergreens, or sometimes checkerberries, belong to the genus Gaultheria, comprising around 170 species.
Japanese boxwood (Buxus microphylla) is an ambiguous term loosely given to any Buxus species native to eastern Asia. Also called small-leaved boxwood, Japanese boxwood may also be used as a common name for Buxus harlandii, Buxus sinica or Buxus koreana. The boxwood cultivar Wintergreen isn't consistently identified with one species. For example, in the American Horticultural Society's "A-Z Encyclopedia of Garden Plants," the cultivar is considered a hybrid between Korean boxwood and common boxwood (B. sempervirens). However, the taxonomic classification of the cultivar in the comprehensive Learn2Grow plant database lists it as a special strain of Korean boxwood (B. sinica var. insignis).
Wintergreens (Gaultheria) produce small, pointed oval, leathery leaves that smell of mint when crushed. These leaves are also arranged in an alternating pattern on the branches. All parts of the wintergreen plant are poisonous, except for the ripe berries.
Japanese boxwood's leaves also are leathery but are larger, more rounded ovals. During winter, the leaves tend to blush bronze, especially in cold temperatures and full sun exposures. Contact with boxwood sap may irritate the skin. The boxwood cultivar Wintergreen is more cold-hardy than other selections and retains green foliage color in winter.
All boxwood shrubs, including those referred to as Japanese or the cultivar Wintergreen, produce tiny greenish-yellow flowers in spring. They are star-shaped, faintly scented and attract bees. These are borne in clusters at the base of leaves. Each loose flower cluster comprises a few female blossoms surrounded by more numerous male flowers, as determined by which sex organ exists in the flower's center. The capsule fruits are rounded, often with three or four finlike protrusions, and later dry with seeds inside.
Wintergreen shrubs (Gaultheria) bear tiny, white, bell- or urn-shaped flowers that resemble those produced on heaths and heathers. They are insect-pollinated, too. Wintergreen fruits are rounded, or bumpy, fleshy and juicy. They are edible. Depending on wintergreen species, the ripe fruits are either red, white or purple-black.
Grow Japanese boxwood shrubs or the cultivar Wintergreen in any fertile, moist, but well-drained soil. They are tolerant of full sun, but if dry soil conditions arise, leaf scorch occurs and the green leaf color dulls. Boxwoods are tolerant of shearing as well as hard, rejuvenation pruning in spring.
Wintergreens (Gaultheria) need an acidic to neutral pH soil that is rich in peat or other organic matter. Plant them in partial shade, much like the dappled light in woodlands. However, they tolerate nearly full sun if the soil is consistently moist and cool. These shrubs tend to send up suckering shoots from the roots. Prune them off at ground level to retain a singular plant silhouette.