Four Types of Hemlock Trees

Eastern Hemlock

• Eastern hemlock (Tsuga canadensis), also called Canadian hemlock, is native from southeast Canada through all of New England, west to the Great Lakes and south through the Appalachian Chain. Eastern hemlock grows to 70 feet, but many of its cultivars are considerably smaller in stature. One is Abbott’s Pygmy, growing to 18 inches and useful as a ground cover or for a rock garden in shady locations. Another is Curley, a dwarf type that grows between 3 and 5 feet tall, making it suitable as an accent plant. Eastern hemlock has the largest range of any of the North American natives, with an ability to grow in USDA zones 3 through 7.

Northern Japanese Hemlock

• Of the 10 types of hemlock species found worldwide, six grow in places such as China, Japan and the Himalayas. Northern Japanese hemlock (Tsuga diversifolia), native to northern parts of Japan, is appropriate as a specimen tree for USDA zones 4 through 7. It grows between 30 and 90 feet in Japan, but as a cultivated plant typically tops out at 40 feet. Northern Japanese hemlock features a pyramidal form, dark, shiny green needles and orange-brown shaded bark. While its needles might scorch when the weather becomes quite hot, this tree has excellent resistance to the hemlock woolly adelgid, a serious pest of this genus of tree.

Carolina Hemlock

• Carolina hemlock (Tsuga caroliniana) lacks the cold hardiness of eastern hemlock, growing in the southern portion of the Appalachians. Suitable for USDA zones 5 through 7, Carolina hemlock grows to 60 feet, possessing somewhat droopy branches. Carolina hemlock cultivars include Arnold’s Pyramid, a 40-foot-tall specimen with a narrow, columnar shape. Greenbrier is a type of Carolina hemlock with weeping branches, growing wider than it does tall, according to the University of Connecticut Plant Database. Carolina hemlock has little tolerance for heat and the drought that often accompanies such weather.

Mountain Hemlock

• The seeds encased in the cones of the mountain hemlock (Tsuga mertensiana) afford nutrition to mammals such as squirrels and chipmunks, as well as many types of birds. This hemlock grows wild to 130 feet from the central California coast north to Alaska. It prefers a peaty or organic soil, growing in sun or shade. This evergreen grows slowly, populating coniferous forests at the sub-alpine level throughout its range. Mountain hemlock’s cones eventually turn black as they age. Its attractive bark is a dark shade of purple-brown.