The Wonderful Wizard of Winter: Native, Snow-Draped Canadian Hemlock

Tsuga canadensis – Native Canadian Hemlock

I try very hard not to play favorites with the plants growing in and around my garden. In fact, you may have noticed that I’ll refer to a preferred species as ‘one of my favorites’, as opposed to ‘my favorite’. After all, I truly love each and every one of them, and I wouldn’t want to hurt any of their feelings. Still, there are a few stand-out, four-season beauties that I can not imagine living without. And in the great world of conifers, I must admit that I am quite partial to our native Tsuga canadensis, commonly known as the Canadian or Eastern hemlock. Though graceful and verdant year-round, Canadian hemlock is a true stunner in the winter garden. After a snow storm —when Tsuga canadensis is cloaked in a fresh coat of powder or ice— it’s impossible not to think of the enchanted forests of fairy tales. I absolutely adore this feathery, magical evergreen.

A few years ago —when I was planting an informal hedge of Canadian hemlock at a private residence— one of my garden clients told me that the shape of the hemlock tree reminded her of a wizard’s hat. Well I already liked this woman, but as soon as she said that, I knew I was going to love working with her. For long as I can remember, I’ve always thought of the Canadian hemlock as a Winter Wizard or even a Warlock (a masculine witch). And as a child, I loved playing beneath the tent-like boughs of hemlock stands; draped in heavy, sparkling white robes after a snow storm. Hemlock is a magnificent native tree; one I never grow tired of praising.

The pliant boughs of Tsuga canadensis are less likely to break when covered in heavy snow and ice

The outer branches of hemlock trees, as well as the tip or leader, are narrow and flexible. The pliant boughs give hemlock the distinctly cascading, somewhat melancholy appearance I find so enchanting. But more importantly, the springy quality of the outer wood gives this native tree an ability to shed snow and ice, avoiding winter breakage –a common problem for other conifers, such as white pine. Hemlock needles are softly rounded; blue-green on the top and silvery on the reverse (the shiny-whitish color is created by tiny openings along the backside of the needles called stomata, which —for lack of a better word— allow the tree to ‘breathe’). When breezes blow through a hemlock’s bows, the pale undersides of its needles are exposed to light; creating a subtle, shimmering effect. Growers have worked with this trees beautiful cascading habit and needle coloration, developing cultivars with mint-tinged branch tips and weeping forms. And because it responds well to pruning, eastern hemlock offers four-season privacy screening when grown as a soft, ever-green hedge in semi-shaded, moist sites. The feathery, deep green needles provide a lovely contrast and sensual backdrop in many of my garden designs.

The Tops of Canadian hemlock (Tsuga canadensis) boughs are covered with dark, blue-green needles

On the reverse side, Tsuga canadensis needles have a light, almost silvery-green color. And when wind blows through the branches, lifting and exposing the undersides of needles to flashes of light, the Canadian hemlock takes on a subtle, gorgeous, two-tone appearance.

With a North American range spanning from Nova Scotia southward to the mountains of Alabama and westward to Minnesota (USDA zones 3 – 8/9) Tsuga canadensis is commonly found in moist, shady woodlands; often along forest streams or cool, north-facing ridge lines. Because of their wide-spread but shallow-root tendency, hemlock are vulnerable to drought, but are less likely to be knocked down in high winds. Here at the northeastern crest of my ledgy site, substantial stands of native hemlock provide a safe haven and nesting habitat for local birds as well as food (seeds, twigs, bark and needles) and shelter for various mammals (including squirrels, porcupines and deer). Although hemlock can grow over 100 feet in ideal conditions, they typically reach 40-70 feet within their native range. When grown as a specimen tree in the open —or planted in small groups—hemlock will develop a soft, full, conical shape (yes, shaped quite like a wizard’s hat).

Because hemlock trees produce acidic tannins, they are quite disease and insect-resistant. However, there exists one recent and notable exception: the wooly adelgid (Adelges tsugae). Closely related to common aphids, this invasive insect pest —introduced from Asia— has the potential to wipe out native, eastern hemlock populations (read more about this pest and how infestations are treated at the UMass Extension Service website here). Although I have not seen the wooly adelgid in my immediate area, I am constantly on the lookout for this destructive insect when pruning hemlock hedges for my clients in early spring. Currently, the only effective, organic treatment for wooly adelgid is thorough, repeat applications of horticultural oil. Entomologists continue to search for natural, biological adelgid controls, and I have high hopes for the tree’s survival. I simply can not imagine the northeastern landscape without my beloved Winter Wizards…

This Canadian hemlock trio forms a soft, four-season screen at the northeastern edge of my garden

Here in late November, the Tsuga canadensis trio provides color and textural contrast and backdrop to the red-twig dogwood, birch and ornamental grasses in the foreground of the entry garden

This beautiful, weeping hemlock (Tsuga candensis ‘Pendula’) —pictured here at The Bridge of Flowers in Shelburne Falls, Massachusetts— is one of the finest examples, and uses of the pendulous form, that I have ever seen. See more photos, and read a bit about The Bridge of Flowers by revisiting this post (click here).

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Article and photos are â“’ Michaela at TGE

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