Pruning Vines for the Winter

Monday • February 15, 2010

The work of caring for a grape vineyard never ends. Probably the most undesirable task of the grape caretaker is trimming. Trimming is cutting the long, dry vines to allow for new growth. It takes place after harvest, during the coldest months of the year in the Midwestern states. Typically, it’s safe to trim after the first frost. In other regions, where it isn’t so cold, the task still takes place whenever the plants lose their foliage. However it is important to trim before the last frost.

Why Trim?

Trimming is important because it stimulates growth of the vines and product. You want to remove buds that suffer freeze damage. Also, too many grape bearing vines will weigh the main vine down and cause it to break. Too much weight on the vines might also cause the wire to break or drop, which would result in loss of product in the long term and create more work replacing wires the next season.

When to Trim

According to Curtis Smith from the agriculture extension of New Mexico State University, some people trim in autumn, but this could lead to freeze damage because the trimming will stimulate growth and if there is a late autumn warm-up the newly formed buds will die. It’s important to leave them unpruned through early winter to protect the plants through the natural process of apical dominance. Apical dominance means that the buds at the ends of the vines have priority of growth, so if they start to form buds and then freeze, trimming them off will stimulate growth on the younger buds that grow at the top of the vines (Smith). The trimming should be completed before spring and especially before the last few frosts. Waiting too long to trim will leave you more susceptible to damaging buds. Also, it is important to trim after the first frost, but don’t trim if the temperature is way below zero because this will also damage the plant.