796 Tsuga canadensisCommon Names: eastern hemlock, Canada hemlock Family: Pinaceae (pine Family)
Eastern hemlock is a handsome and graceful pyramid shaped evergreen conifer. It normally gets 60-80 ft (18-24 m) tall with a rapidly tapering trunk 2-3 ft (0.6-0.9 m) in diameter at breast height, but it can reach as high as 165 ft (50 m) with a 4 ft (1.2 m) trunk. The trunk sometimes forks near the base. Eastern hemlocks don't start producing seeds until at least 20-30 years old, take 200-300 years to reach maturity, and may live 1000 years. Young trees have a slender pointed top shoot that droops and waves in the breeze. Older trees have an irregular rounded crown. The bark is cinnamon-brown with deep ridges and furrows, and 2-3 in (5-8 cm) thick on mature trees. The flat needles are about a half inch long and arranged in two horizontal ranks on the slender spreading to drooping branchlets. The foliage appears as graceful flat sprays, parallel with the ground. The pendant cones are a little less than an inch long and almost as wide at the middle; they are among the smallest of all cones.
Eastern hemlock is a popular landscape tree and one reference lists more than 50 named cultivars in the horticultural trade. 'Aurea' has yellow young foliage. 'Bennett' is a vase shaped dwarf to 5 ft (1.5 m) tall. 'Cole's Prostrate' is a sprawling groundcover that gets only 1 ft (0.3 m) tall. 'Pendula' (a.k.a. 'Sargentii' or Sargent's weeping hemlock) is a mound forming shrub with long, drooping branches; it gets 12 ft (3.7 m) tall and spreads twice that, and is considered by many to be one of the most attractive and graceful of all conifers.
Eastern hemlock, Tsuga canadensis, occurs naturally from Nova Scotia, New Brunswick and southern Quebec west through the Great Lakes region to Michigan and Wisconsin and south through New York and the Appalachian Mountains to northern Alabama and northern Georgia. This is a tree of cool, moist slopes and in the southern part of its range it is confined to high elevations, mostly above 2000 ft (609 m). It is more of a lowland tree in the far north. Hemlock usually grows on shady slopes with a northern or eastern exposure. It may grow in pure stands, but often grows in association with white pine (Pinus strobus), maples (Acer spp.), yellow birch (Betula alleghaniensis) and white and red spruce (Picea glauca and P. rubens, respectively).
CultureSlow growing eastern hemlock can be expected to take 15-20 years to reach 30-40 ft (9-12 m) in height. It does well on acidic soils, calcareous soils, and sandy and rocky soils, so long as the soil is well drained. It does not tolerate air pollution or strong, drying winds. Light: Eastern hemlock grows best in partial shade. It does not do well in full sun. Small trees will die in full sun. Moisture: Eastern hemlock is not drought tolerant. Water young trees especially before the soil dries out completely. Hardiness: USDA Zones 3 - 7. Eastern hemlock may survive in the heat of zone 8, but it does poorly. Propagation: The cultivars of eastern hemlock are propagated from semiripe tip cuttings rooted in summer. The cuttings must be treated with rooting hormone, given bottom heat, misted, and even then you should expect many failures.
Eastern hemlocks are among the best and most popular evergreens for background plantings and for windbreaks and screens. The smaller cultivars are widely used to anchor foundation corners or walkways, and as evergreen hedges. The graceful, fine textured foliage can be used as an accent in virtually any landscape design. The weeping 'Sargentii' hemlock is as fine a specimen tree as can be found.
The bark of eastern hemlock is highly valued for its tannin which is used in the processing of leather. Hemlocks were once harvested solely for their bark and great trees were left to rot in the forest after the valuable bark was removed. The soft, light weight wood is used only for crates, general construction and as pulp for the manufacture of paper. Hemlock is not good fire wood because it pops and spits hot embers. Hemlocks are valuable wildlife trees in their native habitat. The dense evergreen foliage provides protective cover in winter, the leaves are eaten by deer and rabbits, the seeds are eaten by birds and small mammals, and porcupines eat the inner bark.
Native Americans from many unrelated and geographically disjunct tribes used decoctions of hemlock inner bark, roots or needles internally or externally to treat rheumatism and arthritis. The Indians also used it as an antiseptic and a cold medicine. However, there are no modern medicinal uses for hemlock. The "hemlock" that killed Socrates was a totally unrelated biennial herb (Conium maculatum) in the carrot family.
Steve Christman 9/13/00; updated 01/03/01, 12/10/02, 12/4/03