Douglas Fir Vs. Canadian Hemlock

Geography

• The Canadian hemlock's distribution is mostly within the United States, despite its name. The tree does grow in southern Ontario and other southeastern sections of Canada, but the range extends south through New England, the Great Lakes and the Appalachian Mountains. Douglas fir is a staple of the Pacific Northwest and the Rocky Mountains, growing along the West Coast from central California northward well into British Columbia.

Zones and Climate

• Climates featuring hot summers do not promote the growth of either of these species, but the hemlock has a bit more tolerance when it comes to warm weather -- and cold. The Douglas fir grows between U.S. Department of Agriculture plant hardiness zones 4 and 6, while the Canadian hemlock handles the climate between USDA zones 3 and 7. Both trees do best when plenty of moisture, either in the form of precipitation or fog, is a feature of the climate.

Size

• Douglas fir grows much larger in a wild venue than does the hemlock. In parts of the Pacific Northwest, Douglas firs exceed 200 feet in height. Most cultivated tree forms are in the 50- to 80-foot-tall range. The hemlocks, while often boasting a wider trunk diameter than the Douglas fir, grow to 70 feet in a natural scenario -- about what it will attain in cultivation. Cultivars of both trees, no taller than shrubs, exist for use as hedges, screens, group plantings and windbreaks.

Features

• Hemlocks typically have branches that droop down and touch the ground. Douglas firs possess lower branches only when young, with the older specimens losing any lower branches and often having none more than halfway up the trunk. The needles are longer on a Douglas fir, while the cones of a hemlock are less than an inch long, as opposed to the 3- to 4-inch cones of Douglas fir. The bark of both trees is a shade of reddish-brown, detailed with rough fissures.