Western hemlock is a large, native, evergreen tree. Western hemlock has a long slender trunk often becoming fluted when large and has a short, narrow crown of horizontal or slightly drooping branches. Western hemlock is shallow rooted and does not develop a taproot. The roots, especially the fine roots, are commonly most abundant near the surface and are easily damaged by harvesting equipment and fire. Maximum ages are typically over 400 years but less than 500 years.
Western hemlock is generally a good cone and seed producer.
Individuals usually produce some cones every year and heavy cone crops every 3 or 4 years. Each cone contains 30 to 40 seeds. Western hemlock seeds have large wings enabling them to be distributed over long distances. Germination is epigeal. Western hemlock seed appears to germinate well and seedlings grow well on almost all natural seedbeds whether rotten wood, undisturbed bed duff and litter, or bare mineral soil.