Growing a Grape Canopy

Train a grapevine up and over a pergola, and the space below may become your favorite outdoor room.
There’s the unfurling of fresh green leaves in spring, the leafy canopy for summer shade, the tasty dangling clusters of fruit and beautiful changing colors in fall, and the rugged character of gnarled, twisting vines during winter. What’s not to love about such an enticing retreat?

Getting Started

Grapevines get heavy—especially when they’re loaded with fruit—so do construct a sturdy structure supported by posts measuring at least four by four or six by six inches. Pergola, arbor and gazebo designs can get complicated quickly. But regardless of the look, plan for at least 50 square feet of lath or rafters for each grape vine. For example, two vines will comfortably fit on a pergola that measures 10 by 10 feet, or 100 square feet.

Vines need excellent drainage. Although a few roots may drill down 15 feet, most reside within the top three feet of soil. A fast-draining loam is perfect; a gritty, rocky soil is fine. If you are faced with heavy clay, consider building a raised planter that measures at least three feet wide and one to two feet tall. First, dig out at least a foot of the existing soil. Rough up the sides and poke holes in the bottom of the hole. Frame the new planter around the sides of the hole, then fill the planter with a mix of native soil and loose, vegetable-quality potting soil.

Vines will tolerate some shade near the ground. But the branches that clamber over the top should receive at least seven to eight hours of full sun. More sun may promote even better fruiting and an earlier harvest. More sun and good air circulation also inhibit mildew, to which some grape varieties are prone.

Choosing a Grape

If you’re new to grapes and mostly interested in eating them, leave wine grapes in the vineyards and grow table grapes instead.

Wine grapes (Vitis vinifera) are European varieties that typically mature slowly over a long growing season and bear small, thick-skinned fruit containing seeds.

Table grapes (Vitis labrusca), on the other hand, are American varieties, or hybrids resulting from breeding the best traits of both European and American grapes. They are easier to grow, less susceptible to disease and bear larger fruit with thinner skins. Some are seedless, too.

Look for grapes suited to our coastal areas and inland valleys. For example, the popular supermarket variety Thompson Seedless thrives in daytime and nighttime heat in the San Joaquin Valley. Daytime highs in the Santa Ynez Valley may be similar, but nights are considerably cooler.

There’s an extra consideration when growing grapes overhead, which has to do with pruning. Spur-pruned vines are easier to tend and appear less messy than cane-pruned types.

That said, good spur-pruning choices for the Central Coast include Black Monukka, Canadice Seedless, Flame Seedless and Muscat. Cane-pruning choices include Concord, Himrod, Interlaken Seedless, Perlette Seedless and Suffolk Red Seedless.

Training Day

On a conventional trellis or post-and-wire setup, branching begins within a few feet of the ground. However, on a pergola, it’s best that a single, unadorned vine winds up a post, then branches out only after it scales the top. If you site the vine midway along the side of your pergola, install a temporary post or wire that you can remove once the vine climbs onto a beam.

Choose the most vigorous cane, tie it to the post, then remove all other growth. As the cane grows, continue tying it every foot or so, and snip or rub off any emerging buds or canes. Gradually twist the vine around the post, if that’s a look you like.

Let the vine grow about two feet past the top of the pergola, then cut off the tip. This forces lateral shoots to break out about 20 inches back into the vine. These new branches, called cordons, will form the framework for subsequent growth. Train the cordons along the outer edges of the pergola, then direct secondary growth at a 90° angle and spaced two feet apart to create a grid. These secondary arms will produce fruit-bearing shoots the following year.

For the first few years, remove any flowers or emerging clusters of fruit to encourage the vine to spend its energy producing branches and leaves. Once the vine has fully covered the pergola, you can shift focus to the harvest.

Ongoing Care

Irrigate your vine about once a week. Keep water off the leaves to guard against foliar disease. Every spring, apply a two-inch to three-inch layer of compost or loose organic material to provide a slow release of nutrients, retain moisture and hold down weeds.

Prune just as your vines are breaking dormancy in late winter. Fruit will be produced on new shoots that emerge from the previous year’s wood. Remove branches that have already borne fruit and thin any canes that have gone crazy. Spur pruning then calls for cutting back year-old branches (those arms that extend from the cordons) to two or three new buds; cane pruning calls for cutting back year-old branches to two feet to three feet. Detailed instructions can be found in the UC Cooperative Extension’s California Master Gardener Handbook or on UCANR.org and numerous other websites.

A Native Alternative

If you love the look of a grape canopy but would rather fortify wildlife than eat the grapes, plant California wild grape (Vitis californica). The rambling native’s leaves emerge with a grayish sheen in spring, shift to green over summer, then turn yellow and red in fall, while the flowers and fruit nourish bees and birds.

Roger’s Red, a combo of Vitis californica and Vitis vinifera, retains that grayish-green color through summer, then turns an even more spectacular red in fall. The grapes are small and seedy. But birds consider them a delectable feast.