Do Walnut Trees Get Nuts Every Year?

Walnut trees should be able to produce nuts every year.

Walnut trees should be able to produce nuts every year.

Walnut trees are capable of producing nuts every year, but you may experience patterns of high and low yields from year to year. Like many fruit and nut trees, walnut trees are prone to a reproductive pattern known as alternate bearing, characterized by alternating years of heavy crop yield followed by light or absent nut production.

Walnut Development

Walnut trees produce nuts during a two-year process, in which flowers produced in a given year don't mature into nuts until the following year. Female flowers form on the tips of the current year's growth, and on short lateral shoots known as spurs. Although these flowers first appear in early summer, they don't reach maturity until the following spring, usually just after the male flowers appear and release pollen. The walnut crop yield depends on the number of female flowers produced during the first year of the cycle, and successfully pollinated during the second.

Alternate Bearing

Alternate, or biennial, bearing is a natural phenomenon that prevents trees from over-extending their resources. In years of favorable growth conditions and light walnut production, the tree will have plentiful resources and produce a profusion of flowers. The following year, those flowers develop into a bumper crop of nuts. Heavy nut development is costly from a plant-resource standpoint, leaving little for flower production that year.The following year, nut harvest will be scant, but the tree will once again be able to pour resources into flower production. In this way, the tree begins a cycle of abundant nuts one year and relative scarcity the next.

Causes of Alternate Bearing

Alternate bearing is common among fruit and nut trees, but is not an integral part of the tree's reproductive cycle. Late spring frosts, disease or drought will trigger the cycle by severely reducing walnut yield in a particular year, leading to increased flower production the following year. Some walnut cultivars seem to be more susceptible to alternate bearing than others, and older trees are more prone to uneven production than younger ones.

Prevention and Management

There are a few things you can do to encourage even nut production from year to year. In the book "Organic Fruit Production," the authors assert that careful thinning can increase yield by 15 to 20 percent. Similarly, in the publication "Best Management Practices for Establishing a Walnut Orchard," horticulturalist Harold H. Adem recommends girdling branches as a gentler alternative to cutting. Do this by cutting a thin strip, roughly 5/16 ince, from around the circumference of the branch. Finally, vigilant defense against frost, disease and parasites will help prevent sporadic losses and keep annual nut production even.

About the Author

Catherine Gray has been writing professionally since 2005. Her work appears in publications such as "Backhome" magazine and "Northern Woodlands." She holds a Bachelor of Science in biology from Nipissing University.

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