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. The principal requirement for adequate development on any seedbed appears to be adequate moisture. In inland regions, one study showed partial shade to be beneficial in reducing mortality caused by high temperatures and drought. Seedlings that die back to the soil surface commonly sprout from buds near the root collar. Sprouting does not occur from the roots or the base of larger saplings.