Problem: You have plenty of oaks on your property, but the acorn crop is light and inconsistent from year to year.
Diagnosis: You probably have too many trees—both oaks and other species—and not enough oak varieties. Reluctance to cut oaks has led to an overabundance, meaning none get the full amount of nutrients, water, or sunlight they need to reach full potential. You may also need more variety. Common red oaks typically have heavy mast crops only every two to four years, white oaks every four to seven years.
Rx: Survey your oaks to find which trees produce the most acorns, then thin surrounding oaks so the best ones are not crowded. The crowns should not overlap, or very little. Also thin competing species such as maple, gum, sycamore, and hickory.
The increased sunlight and reduced competition for water and nutrients in the soil will result in dramatically heavier acorn crops from each tree. Hire a logger who will take less valuable trees for pulp and firewood if you can’t do this chain-saw work yourself. But first mark exactly which trees he should either cut or save. State forestry departments offer help with this, often for free.
If you do the work yourself, leave the tops in piles or windrows. Deer will browse on them, and they’ll create excellent bedding or corridor security cover.
Preventive: Continue to thin competing young trees sprouting under the crowns of your best oaks, allowing a few select specimens to remain for the future. Plant additional species that bear nuts more consistently. Pin, sawtooth, Shumard, and water oak will provide acorns reliably when common red and white oak crops are light.
Don't bother fertilizing your oaks. A three-year University of Tennessee study found no benefit to the practice.