By Lyn Chimera Our native eastern hemlock (Tsuga canadensis) is my favorite native conifer. We are lucky to have some mature and younger ones on our property. Its graceful beauty, adaptability, and tenacity at being able to hold itself onto ravine walls is a source of wonder. In my mind there is nothing more picturesque in the winter than hemlock with snow on its branches. A true photo op. The fact that the needles stay dark green all year adds to their beauty. Dr. Donald Leopold, author of Native Plants of the Northeast says,” There is no more graceful looking tree at any age in Eastern North America.”
Hemlocks have a wide growing light range tolerating from sun to shade. They prefer acid soil that is slightly moist. In nature they often grow along woodland streams or in large stands of moist woods. On a hot summer day, it is noticeably cooler when you enter a hemlock wood. We are lucky to live where there are many such places. The Adirondacks is noted for its hemlock forests. This is not a small tree. It can attain a height of 60-80 feet sometimes reaching 100 feet high. Their width is 25 to 40 feet. Hemlock needles are quite small, 1⁄4 to 1⁄2 inch. They are deep green on top and underneath are lighter green with 2 parallel silver/white bands. For such a huge conifer their cones are very small, 3⁄4 of an inch long, and egg shaped. The cones look like small ornaments dangling down from the branches.
They make a great addition to a winter door swag. They are slow growing but long lived, reaching maturity in 250 – 300 years! One of the adaptable qualities of the hemlock is they can be a free-standing specimen tree or planted in a group for a green wall effect. They even take to pruning well and develop into beautiful hedges. This, however, requires continual maintenance but is well worth it.
The common name "hemlock" was reportedly given because the crushed foliage smells a little like that of the poisonous herb hemlock, which is native to Europe. The root system of this species is shallow, making the tree vulnerable to ground fires, drought, and wind.
As with many trees, the bark of Eastern Hemlocks changes as the tree matures. When the tree is young, the bark is gray-brown and relatively smooth. As the tree ages, the bark becomes cinnamon brown, with thick, ridges forming flat plates, very easily identified.
The bark of Eastern Hemlock was once a commercial source of tannin, used in the production of leather. At present, the Eastern Hemlock has more limited commercial uses than some other conifers in the region. The characteristics of hemlock wood limit its use to relatively low-grade products, such as structural lumber, pulpwood, and pallets. The bark is currently in demand today, but for landscaping mulch. The Eastern Hemlock makes a poor Christmas tree since its needles fall upon drying and the branches are soft and pliable. Its value as firewood is limited by the fact that the wood throws sparks.
However, the eastern hemlock has a huge role in supporting the ecosystem. Its branches offer shelter and nesting sites for many bird species. The seeds from its cones provide food for birds and small mammals.
Unfortunately, there is an invasive pest, the hemlock wooly adelgid (HWA), related to aphids, that is decimating native hemlocks throughout the eastern US. It doesn’t survive in winter temperatures below 0 degrees, so our cold weather has helped prevent it from being widespread here. However, now that we are experiencing warmer winters, we are seeing the adelgid in WNY and the Adirondacks. This could be an environmental disaster. Oddly, the HWA is most visible in winter when the HWA covers itself with a waxy white coating that is easily visible on the underside of the branches where the needles contact the branches. If you have hemlocks be sure to keep an eye out for these bugs during the winter.