Dates of cone opening range from mid-August at low elevations to early October at high elevations. Seed shed may begin in late August at low elevations and at higher elevations is usually complete by the end of October. Fresh seed may germinate with a 90 percent success rate if adequately ripened, cleaned, and stratified. Losses due to unprepared seedbeds, drought, insects, and rodents may be high. Germination is epigeal.
Seedlings rapidly grow a deep taproot when seeds germinate on mineral soil.
Seedlings will germinate on both litter and bare mineral soil, but development is slow under shade conditions. Planting sugar pine has met with some failure. A low drought tolerance may be the determining factor. On favorable sites, growth increments in basal area of 2.5 percent or more can be sustained for up to 100 to 150 years. Sugar pine is semitolerant to shade and may exhibit poor growth if seedlings are enclosed by brush.