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.
How to Trim
You’ll need:
Clippers or some sort of lopping shear
Walking up and down the grape rows, assess each vine. On each vine, leave approximately 2 to three long vines in each direction on the wire. You want to make sure you leave 90 to 150 buds per vine. At first, you’ll need to count the buds on each vine and estimate the full amount, but eventually you will get an eye for buds per vine. Another way to judge the length is to trim the length to where the vines on the wire meet the vines of the next planted vine. It’s okay to overlap a bit. Be careful, though, not to trim too much because it will limit your crop. It’s important not to trim the vine to death. Try not to leave gaps between the vines.
To read more about Spring, Summer and Fall in the vineyard, see the other articles in this series.
Smith, Curtis. “Pruning backyard grapes in summer.” Blog post. July 23, 2005. accessed July 19, 2008.
