Acorns constitute one of North America's major mast crops, providing a staple food for many types of wildlife. Wildlife populations wax and wane along with the acorn crop, which varies greatly from year to year. Oaks respond to environmental stresses by setting fewer acorns, and some species produce in a cycle that yields a good crop every three to five years. Slow-growing oaks could take decades to reach reproductive age.
Oak trees planted near homes could be large enough to provide shade but still be too young to bear acorns. Many North American oaks need 20 years of growth before flowering, and others may not bear for 40 years. Size also affects acorn production. Smaller trees in a stand of oak receive less light and less nutrition from the soil, and produce relatively few acorns. Larger trees dominating a stand produce acorns at greater rates. Culling trees with poor yields could improve acorn production. Watch a grove for three to five years before deciding which to cull. Individual trees might produce well every second year or every tenth, according to the University of Florida Extension.
The two main groups of oaks produce acorns on different schedules. White oaks, which yield acorns of better quality, require only one year to bring acorns to maturity. Red and black oak acorns stay on the tree for two seasons. White oaks, identified by leaves with rounded lobe tips, tend to produce well as a regional population. If one white oak yields well, other white oaks in the same area should also bear a good acorn crop. Red oaks, marked by leaves with sharp lobe tips, produce by individual patterns. In any single season, some red oaks produce good yields but others do not.
Late frosts, droughts and severe winter cold could all affect an oak tree's acorn crop, even when environmental problems occur before acorns set on the tree. White oaks produce male and female flowers in the spring. If pollinated, the female flowers become acorns by fall. The buds of male blossoms form during spring of the previous year, and the buds of female flowers form late in that summer. One year's crop actually undergoes two years of environmental risk. Red oak flower buds form on a similar schedule, putting any single red oak acorn crop at risk for three years.
Reducing stress on oak trees could help acorn production over the long term. Crowding increases competition for light and nutrients with other trees, so in the home landscape pruning and culling could improve the acorn crop. Fertilizer applications could positively affect the tree, but results vary with individual trees, according to the University of Florida Extension. Cyclic acorn production is normal for oak trees and benefits the species by reducing the numbers of acorn predators. After several poor mast years, a bumper crop of acorns stands a better chance of producing new oak trees.