Growing Grapes for Wine? It's Time to Prune! by Donna Duffy

My neighbor, John Crawford, is a fourth generation vintner who has been growing grapes for about six years in Colorado, and making wine since 1979 using the private label “Crawford Castle. John was previously co-owner of Colorado’s oldest winery, Colorado Mountain Vineyards – now Colorado Cellars. Here's John's advice on pruning vines for maximum grape production. 

For first year vines, plant them within a few days of their delivery from the nursery and don’t do any pruning, just let them grow. This gives the vines a chance to build their root system and store carbohydrates, providing energy to grow strong trunks and canes.

Pruning starts in the second year. There will probably be several shoots growing from the main vine – when they are several inches long, find the strongest two and remove the rest. Some grape growers only keep one strong shoot, but John keeps two as a safeguard. Remove the side spurs, then tie these main shoots to a pole for straight growth. When a shoot gets about four feet tall, cut the top off to encourage side growth. One of the most difficult parts of growing grapes is pruning off all that growth in the second year – but don’t be sentimental! You are building the base for a strong, healthy grapevine in future years.

In the third year, intentional pruning is critical to control growth, promote healthy vines and provide an abundance of fruit. Grapevines are best pruned during the cold months of February and early March before the first buds emerge. If you miss this window of opportunity, wait until the leaves are fully developed to do your pruning.

Take these steps to prune your vines when they are at least three years old:

1) Follow a growing vine tip (called a spur) back to the older wood from the previous year. 2) Then, come forward leaving between four and ten buds and prune off the rest. John leaves three buds on every strong spur. 3) If you have weak, brittle spurs, cut them off. 4) Step back and take a look, your spurs should be about three inches apart. In future years, you’ll choose the three strongest spurs and they will be the base of your grapevine for the life of the plant.

Finally, a couple of pointers on fertilizing. If you are growing grapevines to harvest grapes, fertilizing is not really needed if your soil was amended with organic matter at the time of planting. However, if you are more interested in growing a leafy vine (as in a barrier), application of a high nitrogen fertilizer in April will result in lots of leafy growth.

Pruning grapevines is complex and multi-phased. An excellent resource is the Colorado Grape Growers’ Guide, downloadable at: http://www.ext.colostate.edu/PUBS/Garden/550a.pdf