Scientific Name
Tsuga canadensis
The eastern hemlock is one of the largest and longest-lived conifers of the eastern U.S. with a native distribution from the southern Appalachian Mountains continuously northeast to encompass Pennsylvania, New York, all the New England states, adjacent Ontario, Quebec and the maritime provinces of Canada. It also extends westward to northern Michigan and Wisconsin. Some have been verified to have lived more than 500 years. The species has been severely challenged beginning in the 1960s by a sap-sucking insect, the woolly adelgid. Initially the destruction was concentrated in the southern part of the range, but it’s now believed to have affected 90% of the native range. Biological controls for the adelgid in the form of insect predators have shown some effectiveness so far, but the situation is dire. For individual landscape trees there are some effective chemical treatments.
Prior to the adelgid issue, hemlock was a popular and useful tree, prized for its soft greenery, fine texture, graceful often drooping branches and especially its ability to prosper in shady locations. The dark green needles are short, less than an inch long, and are attached to tiny pegs. The cones are small, an inch or less in diameter, and dangle on slender stalks. The species can handle well below −30°F and is more likely to be stressed by very hot and dry weather. The form of the tree is pyramidal, and it may grow to about 50 feet in cultivation (at present the largest of the few that exist in Colorado is 42 feet tall). The Regis hemlock was planted in the spring of 2020 when it was about 5 feet tall and has not grown especially rapidly.