Speculative piece educating public audiences on grapevine dormancy and the impact of spring freezes on the North American grapevine industry.

In the northern United States and Canada, frigid temperatures and piles of snow settle on roads and houses during the winter months. The same holds true in the vineyards as well. To survive this weather, grapevine varieties grown in these cold climates fall dormant in the winter months. Then, in the spring, grapevine buds gradually exit their protective dormant states and reach “budbreak,” at which point green tissues erupt and can begin to grow into shoots and grapes.

The first bud tissues that erupt in the spring are very fragile. If a spring freeze occurs after budbreak, it can cause damage or even death to the bud tissues, which can have other negative effects later in the growing season. For growers and wineries, this can mean devastating yield losses or even changes to the chemistry of the grape juice that is produced.

The good news? In the event of spring freeze damage, grapevines have a natural backup plan. Grapevines have “compound buds,” meaning every bud that initially develops (the “primary” bud) is accompanied by secondary and tertiary buds that can begin to grow if their predecessors are damaged.

The bad news? Compound buds aren’t the perfect replacement. Secondary and tertiary buds are generally less fruitful than the original primary bud, meaning growers may still end up with reduced yields. Additionally, after a bud is damaged, its backup needs time to grow in its place, potentially causing delays in shoot development and fruit ripening.

As a result, spring freezes are a big problem for growers and for the greater wine industry – and one that may become even more relevant in the face of climate change. As a result of warming winter and spring temperatures, grapevines may reach budbreak earlier in the season, leaving more time for the fragile green tissues to be exposed to spring freezes that may occur.

Now, the big question: how do we protect the vines and wines we love?

Growers and viticulturists across the world use a variety of methods to help defend vineyards against spring freeze damage, although many come with costs. Some growers set up heaters or fans in their vineyards to warm and circulate the air, although this can be an expensive endeavor for smaller vineyards. Modified pruning practices can also be used, although this can be a time consuming and labor-intensive process, especially for large commercial operations. Scientists are in the process of testing new strategies as well, such as compounds that can be applied by growers to reduce spring freeze damage. Thus, while spring freezes currently pose a risk to vineyards, the collaborative efforts of growers and researchers provide hope for a more fruitful future.

What are Spring Freezes?

Tree Physiology