Why Doesn't My Oak Tree Produce Acorns?

Did your oak tree experience some form of environmental stress recently (drought, frost, hail damage, etc.)?

Is your oak tree relatively young?

Was the spring very rainy or with extremely little wind?

Has your oak produced a large number of acorns in the past few years?

Are there any signs of pests or diseases on your oak tree?

Stressed trees often abort their fruit (acorns in the case of oaks). Trees lacking in vigor and/or food reserves may have the energy to produce leaves, but may not also have the reserves to bring fruit to maturity. Or when the fruit is produced, it may not have the size and quality of a tree with greater vigor.

Some oak trees need lots of time before they start producing acorns. For example, the pin oak (Quercus palustris) and the white oak trees (Quercus alba) produce their first acorns at the age of 20, and bur oak (Quercus macrocarpa) need to be at least 35 before it starts producing leaves. If your tree is young, don't worry, the acorns will show up eventually.

Because oaks are wind-pollinated, weather conditions can greatly affect fruit set. Frequent rains at the time when oak catkins are shedding pollen in spring reduce pollination efficiency, as does calm, windless weather. If pollen can’t get from the male catkins to the female flowers, acorn production will be reduced.

Many plants, oaks included, are subject to a phenomenon called alternate bearing. This occurs when a plant bears a heavy “bumper crop” one year and then fails to produce another large crop for one or several years after. If your oak is in the red oak family, then you can typically expect heavier acorn crops every 3-5 years. If your oak is in the white oak family, then you can typically expect heavier acorn crops every 4-7 years.

Some pests and diseases can have a similar effect as that of the environmental stresses. Sick or stressed trees will put more energy into leaf production than in fruit production. Some animal pests, mainly squirrels often feed on acorns and in extreme cases can eat all of the year's yield.

Plants that exhibit low nutrient reserves will often produce few, or low-quality fruit. For trees growing in the wild, this may not occur, as plants obtain many of their nutrients from the continual decay and recycling of the organic litter that falls to the soil. However, when grown in yards and parks people often rake up and remove this litter layer in home gardens so the soil cannot absorb any new nutrients. If this is the case, you will need to use fertilizer to enrich the soil for your oak.