Canada hemlock Tsuga canadensis

Eastern Hemlock is an evergreen tree that may grow 80 to 100 feet tall. The leaves are flat with single needles that have two lines of white stomata on the underside. The bark is gray-brown and scaly in young trees. As the tree ages, wide ridges and furrows develop. In spring, small, yellow, male and small, light green, female flowers mature. The tree produces a 3/4-inch cone that matures in the fall.

Found in the Pinaceae family which is commonly known as the pine family. Is effected by the wooly adelgid. Commonly used for landscaping but has little to no value commercially.  

The Eastern hemlock grows in average, medium moisture, well-drained soils in part shade to full shade– it is a natural understory tree in wild stands.  It is best sited in part shade in sheltered locations protected from strong drying winds and hot afternoon sun.  It will tolerate full sun in cool northern climates, but dislikes the hot and humid summers of the deep South (particularly south of USDA Zone 6) where sunscald may damage the foliage when temperatures consistently exceed 95 degrees F.  It is intolerant of drought and should be watered regularly in prolonged dry spells, particularly when plants are young.  It appreciates a thick winter mulch.

Its lower branches often dip toward the ground. The thick and ridged bark on mature trees is red-brown to gray-brown.  Its wood, although soft and brittle, is harvested for lumber and pulp. 

It is similar in appearance to another native relative, T. caroliniana.  The trees can be told apart by the length of the leaves and structure of the stems, with T. Canadensis having shorter leaves and cones as well as leaves that lay flat along the stems.

Fire Risk: This plant has a high flammability rating and should not be planted within the defensible space of your home. Select plants with a low flammability rating for the sites nearest your home. 

Insects, Diseases, or Other Plant Problems:  A healthy plant in the proper environment has few problems. Potential disease problems for plants in the genus Tsuga include needle blight (needles turn yellow and die), canker, rusts, and rots. Potential insect problems include bagworms, borers, leaf miner, sawfly and spider mites. The foliage may scorch in very hot weather. A prolonged drought can be fatal to this tree.

Hemlock woolly adelgid (HWA) is a tiny (1/32”) sap-sucking insect (a relative of the aphid) that has recently become a serious threat to the survival of native hemlocks in the wild in the eastern United States. HWA was accidentally introduced into the U. S. in the 1920s from Eastern Asia. It has been known to exist in the Pacific Northwest since 1927 but was first observed in the forests of Virginia in the 1950s. It has now spread from Virginia into the southern and middle Appalachians. The inability to survive cold winters has so far substantially limited HWA’s northern spread to as far as Massachusetts, but northward expansion into much of New England is expected as winter temperatures continue to moderate. HWA has killed most of the old-growth hemlocks in the Great Smoky Mountains National Park and 95% of the hemlocks in Shenandoah National Park. HWA was discovered in Pennsylvania’s Allegheny National Park in November of 2013. Treatment of HWA is available (pesticides containing imidacloprid or dinotefuran), but control of this pest is very difficult.

Quick ID

• Branches in flat planes
• Linear leaves with 2 glaucous bands below
• Occasional leaf upside-down along minor twigs
• Pendulous ovoid cones from branches

VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers" a plant identification course offered in partnership with Longwood Gardens.