Hemlock Varieties

Western Hemlock

• Western hemlock (Tsuga heterphylla) has a similar range to the other Pacific Coast variety of hemlock, mountain hemlock. It is native from northern California up the coast to Alaska, with pockets of these trees growing in Idaho, Montana and British Columbia. Suitable for cool, damp climates in U.S. Department of Agriculture (USDA) Plant Hardiness Zones 5 through 8, mountain hemlock may grow to 100 feet high in time. Its new needles are light shades of green, contrasting with the darker older growth. As with all hemlocks, western hemlock excels in full sun, but it also develops in full shade. Its branches droop downward, with elliptical, 1-inch-long cones and tints of light brown.

Mountain Hemlock

• In cultivation, the mountain hemlock (Tsuga mertensiana) grows to 30 feet; in the wild, it tops out at 100 feet. Mountain hemlock’s needles vary between dark green and shades of blue-green. The tree grows at high elevations in the Northwest. Mountain hemlock grows in an array of sites, in shade or sun. It has use as a screen or hedge, tolerating pruning to keep it in shape. It is a good landscaping tree for Zones 5 through 8, doing well despite short growing seasons and lengthy, but somewhat mild, winters, according to the Washington State University Clark County Extension.

Carolina Hemlock

• The Carolina hemlock (Tsuga caroliniana) is not a common tree in nurseries, states the University of Connecticut plant database. Find this variety of hemlock in specialty nurseries. Hardy to USDA Zone 5, this Appalachian Mountains species grows to 60 feet. Among its best assets is its red-brown, fissured bark. Avoid placing Carolina hemlock in a dry site where the wind affects it. This tree comes in a cultivar known as "Arnold’s Pyramid," a 40-foot-tall specimen appropriate for mass plantings to create groves. Carolina hemlock, as with others of its genus, is vulnerable to an insect pest called the hemlock woody adelgid, a bug that, when left to its own devices, is capable of killing a full-grown tree in 36 months.

Eastern Hemlock

• Eastern hemlock, or Canadian hemlock (Tsuga canadensis), grows in the Northeast, the Appalachians and southeast Canada and reaches between 40 and 70 feet high. Multiple cultivars exist for this hemlock, including dwarf forms that only grow 18 inches tall. Eastern hemlock, suitable as a privacy screen or windbreak when planted in succession, does not withstand drought, especially when it is immature. It does best in a cooler climate where moisture is plentiful. Eastern hemlock serves as a specimen tree, displaying the same tolerance for sun or shade as its close cousins. Use it in USDA Zones 3 through 7.