The Importance of Pruning a Grapevine

Grapevine Basics

• All grapes are sun-loving plants. Without ample sunlight, the leaves cannot produce as many carbohydrates in photosynthesis and thereby grow as well or create as many flowers and subsequent fruits. If a grapevine becomes a crowded thicket or tangle, it shades itself, limiting its own vitality and productivity. Grapevines also bloom and bear fruit on year-old wood: the vines that grew and matured by the previous autumn. The plant will survive if winter cold kills it back to the roots and it will rejuvenate in spring, but no flowers or fruits occur on the current year's vining stems.

Pruning Value

• Pruning a grapevine maximizes space in a garden while promoting the best growth habit and conditions to increase flowering and fruiting. Grapes are trained to grow on trellises. This system ensures the plants have excellent exposure to sunlight and air circulation. Pruning vines controls how much leaf and stem growth occurs, reducing the concerns of shading itself. Pruning also removes dead or diseased canes, improving the plant's overall vitality. Reducing the amount of year-old wood on grapevines also controls the number and quality of fruits produced. The fewer fruits that are left to develop, the larger each grape becomes and the better the flavor and sugar content. Too much pruning limits the number of fruits for harvest. It's a scientific art, balancing the need to prune with maximizing production of excellent individual fruit flavor and size.

Pruning Methods

• The two most widely used grapevine pruning methods are referred to as cane or spur. Either may be employed on grapes, but certain species or cultivars of grapes perform better -- in flower and fruit production -- if one method is used. However, some grape types prosper if either method is used. Plant nurseries and literature, including plant labels, reveal which pruning method is best for each grapevine variety. Cane and spur pruning techniques differ in the number of buds retained on year-old vine canes. Spur pruning is a simpler method, especially for novice gardeners.

Timing Considerations

• The best time to conduct pruning on grapevines is when they are dormant, just before the plants naturally begin to sprout new growth in spring. Dead, broken or errant stems may be pruned any time of year. Major annual pruning maintenance done in very late winter allows you to remove any dead tissues resulting from cold temperatures that winter. The barren stems also give you an unobstructed view of the grapevine's branching structure and location of buds.