Eastern Hemlock

Eastern Hemlock (Tsuga canadensis), also called Canada hemlock, Canadian Hemlock, Hemlock Spruce, Spruce Pine.

Eastern hemlock is a woody, needled evergreen tree in the Pinaceae (pine) family. It is native to eastern and central Canada and the United States. In North Carolina, it is found primarily in the mountains and in a small area located in Piedmont.

Eastern hemlock needs moist but well-drained, somewhat acidic soils in sun to part shade. It grows best in areas with cooler summers and doesn't tolerate drought. Trees can endure pruning as a hedge but look best unpruned. Propagate from seeds gathered from cones just beginning to open; provide moist chilling for 100 days before planting.

A beautiful conical evergreen with drooping branches and tiny cones, the healthy eastern hemlock makes a lovely specimen tree in a home landscape. Individual trees can reach heights of 40 to 70 feet and widths of 25 to 35 feet, so dwarf cultivars are best for home landscapes.

Identification

The leaves are small ½-inch glossy needles that have a white underside in 2 opposite rows. Its needles are attached by slender stalks ending with woody pads. The margins minutely dentate, especially toward the apex. The linear green needles are spirally arranged around the branch. Along the main branches, some needles are laying on their backs.

On mature trees, the bark is reddish-brown to grayish-brown with a thick, scaly, or ridged surface with irregular fissures.

No flowers. Pollen cones yellow rounded bumps that resemble a blackberry 1/8" across are found in groups near the tips of branches.

The young female cones are green, oval, and have closed scales. As the cones mature, they are brown and 3/4-inch long. The scales will open to release their seeds.

Habitat and cultural conditions

Light: Dappled Sunlight (Shade through upper canopy all day); Deep shade (Less than 2 hours to no direct sunlight); Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil texture: Clay; Loam (Silt); Sand. Soil pH: Acid (<6.0). Drainage: Good Drainage; Moist.

Uses and significance

The cambium is used by Native Americans for breads and soups as well as with dried fruit and animal fat for pemmican. The leaves, which are high in vitamin C, are also used for tea. The bark was once used for tannin for leather production.

It provides winter and extreme weather coverage. Red crossbills and small mammals eat the seeds. Ruffled grouse eat the buds and white-tailed deer browse the foilage in winter. It is an important thermal cover component along streams for amphibians and fish. It also provides cover and shelter for turkey and white-tailed deer.

Insects, diseases, and other problems

Hemlock wooly adelgid is a major pest. Other insect problems include elongate hemlock scale, hemlock borer, fir flat-headed borer, hemlock looper, hemlock rust mite, hemlock sawfly, bagworms, spider mites, gypsy moths, spruce budworm, spruce leaf miner, and grape scale. Disease problems include leaf (needle) blight, cankers, blister and needle rusts, and sapwood rot. Environmental problems include sun scorch in hot weather and sensitivity to drought.

Cultivars / varieties

• 'Curly'
• 'Gentsch White' — dwarf shrub, slow growing, up to 4.5 feet tall, silver white needles on the tips of branches
• 'Gracilis'
• 'Jeddeloh' — Shrubby form
• 'Pendula' — shrub, 2 feet tall, 5 feet wide, weeping habit
• 'Sargentii' — 10'-12' tall 20'-30' wide, dense, weeping, great form

Plant details

Further reading

• N.C. Extension Gardener Plant Toolbox: Tsuga canadensis — primary source for the plant details above