Flowering and Fruiting - The species is monoecious; male and female strobili are produced on different branches of the same tree, at different heights-the reddish male strobili on lower branches and the green female strobili nearer the treetops and farther from the trunk. When grown in the open, western redcedars begin to produce strobili at 10 years of age and usually every other year thereafter.

Seed Production and Dissemination - Each mature strobilus usually produces only 3 to 6 seeds, but the strobili are often numerous and heavy seed crops are common. Seeds are small; they fall faster and do not fly as far as the seeds of western hemlock, Sitka spruce, and Douglas-fir, but dissemination is adequate within 100 m of a seed source. The seeds usually germinate well without stratification, and they retain their initial viability for at least 7 years when stored dry.

Seedling Development - Most seeds escape rodent and bird predation, but seedling mortality is high during the germination period. Western redcedar seedlings are less tolerant of high soil temperature and of frost than are the seedlings of Engelmann spruce, grand fir, and Douglas-fir. The exposed upper foliage of young redcedars often sunburns severely.

Vegetative Reproduction - Three types of natural vegetative reproduction occur: layering, rooting of fallen branches, and branch development on fallen trees. The resulting "veglings" are more abundant than seedlings in mature Idaho stands. Saplings that have been knocked down in the western Cascades often regenerate when their branches root.