The gracefully drooping branches of hemlocks (Tsuga sp.) make them an attractive tree in woodland gardens. These conifers grow best in United States Department of Agriculture plant hardiness zones 4 through 7; some species thrive in the coastal
The gracefully drooping branches of hemlocks (Tsuga sp.) make them an attractive tree in woodland gardens. These conifers grow best in United States Department of Agriculture plant hardiness zones 4 through 7; some species thrive in the coastal and mountain areas of the western United States, while others do best in the eastern U.S. Most hemlock species reach at least 30 feet when mature, although some dwarf varieties do exist. Before deciding to plant a hemlock, be aware of their mature size and understand the concerns of planting large trees near your home.
Western hemlock's (Tsuga heterophylla) native range includes much of the western United States and Canada, growing from Alaska to northern California from the coast to lower mountain elevations. At maturity, western hemlocks have a height of 70 to 130 feet and a width of 20 to 30 feet. This hemlock grows quickly, making it good for filling in gaps in the landscape or for replacing fallen trees. If trained on stakes, the "Thorsen's Weeping" variety can grow into a striking weeping form; without training, this variety can be used as a ground cover.
For a hemlock that grows in higher elevations, look for mountain hemlock (Tsuga mertensiana). This hemlock species is native along the Sierra Nevada range and other mountainous areas of the western United States. Mountain hemlock is a good choice if you want a slow-growing conifer. When mature, mountain hemlock measures 50 to 90 feet tall and 20 to 30 feet wide; those kept in gardens tend to stay at the lower end of the size range. This tree does not do well in lower elevations and prefers partially shady conditions. For a dwarf variety, look for "Elizabeth," which remains only 1 foot tall and 3 feet wide.
Northern Japanese Hemlock
Northern Japanese hemlock (Tsuga diversifolia), a native of Japan, is one of the smaller hemlocks and grows slowly to 35 to 60 feet tall and 25 feet wide. This hemlock tolerates windy conditions well and is popular for its higher resistance than other hemlocks to pests. "Loowit" is a dwarf variety that remains 1 to 2 feet tall and 2 feet wide.
The standard Canadian hemlock (Tsuga canadensis) reaches a mature height of 40 to 70 feet with a 20- to 35-foot-wide canopy. This species is one of the more popular hemlocks planted in the eastern United States and Canada. Dwarf varieties that reach only 3 to 4 feet tall include "Gentsch White" and "Moon Frost." "Pendula" has a weeping form that grows to 10 feet wide but only 5 feet tall.
Large Tree Concerns
The primary concern when planting any large tree is choosing a space where it has ample room to grow. Planting a hemlock within 10 feet of a structure crowds the tree and risks damaging it or the building. Hemlocks, like many other conifers, have shallow root systems, making solitary trees unstable in windstorms. Because of this, the trees should be planted either in clusters or in locations where, if they fall, t