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Canadian Hemlock Trees

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Picture of Canadian hemlock tree branch dusted with the winter's snow.

Picture of a graceful Canadian hemlock tree branch dusted with the winter's snow. Click the picture to open a mini-photo gallery.

David Beaulieu

Plant Taxonomy of Canadian Hemlock Trees:

Plant taxonomy classifies Canadian hemlock trees (aka eastern hemlock trees) as Tsuga canadensis (commonly misspelled as Tsuga canadiensis).

Plant Type for Canadian Hemlock Trees:

Canadian hemlock trees are classified as evergreens and as conifers.

Characteristics of Canadian Hemlock Trees:

Slow-growing and long-lived, Canadian hemlock trees in the wild may reach 80 feet tall or higher, with a spread of 25' to 30' (for information on compact cultivars developed for landscape usage, see below). These fragrant plants are pyramidal or conical in shape, and their small needles give them a fine texture. The needles are dark green on top and light green underneath. The bark of Canadian hemlock trees at maturity may be cinnamon-red or reddish brown. Click on the picture at right to open up a mini-photo gallery.

USDA Plant Hardiness Zones for Canadian Hemlock Trees:

Canadian hemlock trees are best grown in zones 3-7. They are indigenous to eastern North America.

Sun and Soil Requirements for Canadian Hemlock Trees:

Canadian hemlock trees require a soil that is moist but that offers good drainage. They prefer an acidic soil. Shallow-rooted, they also need protection from the wind. But unlike many large trees, Canadian hemlocks will tolerate quite a bit of shade.

Landscape Uses for Canadian Hemlock Trees:

Canadian hemlock trees can serve as specimen plants or as "living wall" privacy screens. Compact cultivars, which are essentially shrubs (see below), are commonly used as hedge plants and/or in foundation plantings; if you begin pruning them when young, they are fairly easy to shape. Two virtues of Canadian hemlock trees are that they are shade tolerant and make relatively little mess:

  • They offer one of the few options for screening plants in shaded areas
  • Pine trees, with their large needles and cones, are known to be messy. But the needles and cones of Canadian hemlock trees are much smaller.

Canadian Hemlock Trees, Socrates, and Poison Hemlock:

The poison that famously killed the Greek philosopher, Socrates was not derived from the tree we've been discussing. Rather, poison hemlock is Conium maculatum. Another hemlock that is poisonous is water hemlock (Cicuta maculata).

Caveats in Growing Canadian Hemlock Trees:

In addition to their being prone to uprooting in wind storms, Canadian hemlock trees have two major drawbacks: they are susceptible to the wooly adelgids scourge (which is raging in eastern North America at the time of this writing, 2007), and they are also a favorite snack of Bambi, so avoid them if you are seeking plants for deer control.

Canadian Hemlock Trees in History:

"One of the primary coniferous sources of tannins is the bark of the eastern hemlock, Tsuga canadensis, a tree that is widely distributed across eastern North America. The bark of this tree has a tannin content of about 10-12 percent and was used to tan sheepskins and heavy leather for shoes in the United States during the late nineteenth and early years of the twentieth centuries," according to the U.S. Forestry Dept. publication, Non-Wood Forest Products From Conifers.

Cultivars of Canadian Hemlock Trees for Landscape Usage:

There are many cultivars of Canadian hemlock trees that have been developed for landscape usage -- specifically, for circumstances in which a tall tree would be undesirable. I list but a few here, to provide some indication of the range of options available.

Compact cultivars include the dwarf, 'Gentsch White.' This rounded, compact, shrub-like plant attains only 4 feet in height (by about the same width).

'Aurea Compacta' (aka 'Everitt's Golden') is one of those evergreens that's not green, instead bearing golden foliage. These Canadian hemlock trees reach 8-10 feet in height, with a spread only about half that.

The 'Sargent' (or 'Pendula') cultivar has an attractive weeping form. It is supposed to grow 5'-8' tall (and twice that in width), but I've heard of it reaching greater heights. Another weeping form suitable for use as a hedge shrub is 'Cole's Prostrate.'

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