Common Name: western hemlock
Type: Needled evergreen
Family: Pinaceae
Zone: 6 to 8
Height: 0.25 to 0.50 feet
Spread: 1.00 to 5.00 feet
Bloom Time: Non-flowering
Sun: Part shade to full shade
Water: Medium
Maintenance: Medium
Suggested Use: Ground Cover
Leaf: Evergreen
Other: Winter Interest
Tolerate: Heavy Shade
Culture
Grow in average, medium moisture, well-drained soils in part shade to full shade. Site in locations protected from hot afternoon sun. Prefers cool, moist conditions in part shade. Intolerant of drought and should be watered regularly in prolonged dry spells, particularly when plants are young. Best growth occurs in a moisture-laden atmosphere in temperatures that are cooler than those found in the eastern U.S.
Noteworthy Characteristics
Tsuga heterophylla, commonly known as western hemlock, is a pyramidal needled evergreen tree of the pine family. It features a narrow pyramidal crown that typically grows in cultivation to 70-150’ but may soar to as much as 250’ tall in the wild. It is the largest of the hemlock trees. It is native from Southern Alaska south through British Columbia, Washington, Oregon and those parts of northern California which are west of the Cascade Mountains plus in the northern Rocky Mountains in Canada and the northern U.S. Trees typically do not perform well outside of their native range. Needles (1/4” to 3/4” long and to 1/16” wide) are shiny dark green with white rows beneath. Cones grow to 1 1/8” long, and are pendulous (hang from the branch tips). Reddish-brown bark is up to 1.5” thick and develops deep scaly ridges. This species is the state tree of the State of Washington.
Genus name of Tsuga is derived from the Japanese name for trees in this genus.
Specific epithet comes from the Greek words heteros meaning different and phyllon meaning leaf.
‘Thorsen’s Weeping’, by contrast, is a dwarf, prostrate, ground cover version of this tree. It features emerald green foliage and procumbent branches. It can sprawl along the ground as a ground cover to only 4” tall and to 5’ across over the first 5 years. If staked or otherwise supported to a desired height, it can grow over time in a cascading mound to the desired height, typically 3-5’ tall, with gracefully weeping branches which sweep to the ground.
Problems
A healthy plant in the proper environment has few problems. Potential disease problems for plants in the genus Tusga include needle blight (needles turn yellow and die), canker, rusts and rots. Potential insect problems include bagworms, borers, leaf miner, saw fly and spider mites. Woody adelgid (an aphid) is particularly troublesome in the Northeast where it can be fatal (has spread significantly since the 1950s). Foliage may scorch in very hot weather. Plants are generally intolerant of urban pollution.
Uses
Dwarf evergreen conifer for ground cover or trained as an upright drooping specimen to 3-5' tall. Rock garden. Specimen. Garden accent.