Trees begin seed production between 10 and 12 years of age. Limited tests show seed viability does not decline with age. Hot fire probably kills some seed. Laboratory tests show that germination rates of seed from mechanically opened cones are greater than those of cones opened by oven heat treatment. Knobcone pine germinates earlier than other pines.
Seedlings require bare mineral soil for establishment.
Seedlings establishing on fertile sites compete poorly with chaparral shrubs and other tree species. The climate in which knobcone pine grows is mediterranean, characterized by wet, mild winters and hot, dry summers. Water-retaining capacity of knobcone pine soils are often favorable to its growth. Slope angles range between 0 and 38 degrees but are most commonly steep and subject to continual erosion. Fire creates the conditions necessary for its continued survival.