All About Grapevine Pruning

By mid-February, vines still lie dormant in vineyards across California. However, the winemaker and the vineyard manager are hard at work planning the single most important operation of the year:

The Pruning

February is a busy period in the vineyard. Nothing is really happening with the vines themselves, but vineyard workers are keeping their pruning shears sharpened, for vine after vine and acre after acre. This is a highly skilled task, mastered by only a very few.

Why is pruning so important?

• Pruning will determine the crop for the current season and the next season. The precise cuts made on the spurs (3 to 5 inch-long 1 year wood-bearing viable buds) and the canes will dictate two consecutive grape productions.
• Pruning keeps vines healthy, getting rid of dead, diseased or damaged wood.
• Pruning provides steady grape production over several decades.
• Pruning allows for and maintains open spaces between the spurs, which encourages dry and sunny conditions for the grapes to ripen.

Below you will find the two main types of trellising systems you can encounter:

Spurs or Cordon Pruning – 

Cane Pruning – 

Cane-pruned grape varieties, such as Thompson, are always more difficult and expensive to prune because great care must be taken in selecting wood. Each cane is pruned back to between 24 and 36 inches based on the vigor of the vine. The goal is to leave 6 to 10 well placed buds on each cane for fruit and wood production.

More important than the number of canes is the quality of canes. Medium diameter, round, well-browned canes with buds about 3 to 3.5 inches are optimal. The buds should be plump and well exposed to sunlight. If the canes develop in the shade, the fruit quality will be compromised.

The Saint Helena vineyard pictured above produces one of our most popular red wines (you’re just going to have to guess) and is designed for Cordon Pruning. This fifteen-year-old vineyard is now at its peak.The buds, growing on the crown and the canes, are ready to burst during this coming 2015 growing season.

No matter what method is employed, growers agree that it takes a special kind of expertise to properly prune a grapevine. Pre-pruning can be done with a machine attached to a tractor or by robots similar to the one below.

But nothing can replace the human touch and decision-making ability the winemaker or vineyard manager provide.

Pruning is truly an art.