Grapes

California is famous for its wine grapes, but did you know it is easy to grow your own table grapes at home?

Not only will you get sweet, luscious grapes, but the vines can be trained over a patio or pergola, providing a nice shady spot in summer!

Princess seedless white grapes

How to grow grapes

• Select a site with full sun and good drainage.
• Build and install a sturdy trellis to support the vines and ensure good sun exposure.
• Start with one-year old bare root grape vines or healthy cuttings.
• Trim off any broken or damaged roots.
• Soak the vines in a bucket of water for 1-6 hours, depending on how dried out they feel.
• Dig planting holes that are 2-3 times the diameter of the plant.
• Place the vines 6-10 feet apart with two bud spurs at soil level.
• Water well at planting time to help the soil settle around the roots.
• During the first two years, allow vertical and horizontal shoots to grow so the leaves can produce energy for a strong root system. You may need to  provide a vertical stake to help the shoots reach the trellis.
• Once the vine is established, select the strongest vertical shoot to become the trunk and remove all the others.
• Start training vines during the winter, when they are dormant. The main trunk should be ‘headed’ (trimmed) when it reaches the top trellis wire. Canes should not be not be cut during the growing season.

Pruning grape vines 

The variety of grapes being grown determines which of two pruning methods to use. Grapes are either spur-pruned or cane-pruned. This is because different grape varieties produce fruit on different bud spurs.

Cane pruning leaves only the trunk and two to four shoots from the previous year’s growth to be trained along support wires. New buds will emerge from these canes to produce leaves and fruit. ‘Thompson Seedless’ and ‘Concord’ are cane-pruned grapes. One cane-pruning method is called the Four Arm Kniffen method and the University of Maine offers an excellent how-to video here.

Spur pruning leaves the bilateral cordons, or horizontal branches, permanently in place. In spring, new growth will emerge from this old wood. ‘Flame Seedless’, ‘Tokay’, and ‘Ribier’ are spur-pruned grapes. In either case, you will want to trim each cane to have no more than 14 spurs. Otherwise, all the plant’s energy will go into vegetative growth, rather than producing grapes.

Irrigating grapes

While most of a grapevine’s roots are in the top 3’ of soil, some of those roots can go down as much as 15’ deep! Grapes perform best when they are watered deeply and allowed to dry out between waterings. The amount of water needed depends on the type of soil, the depth of the roots, and the weather. On average, a deep watering every 2-3 weeks during summer is adequate. During cooler or wet weather, little or no water is needed. Once your vines have bloomed, it is important to water regularly. As fruit develops, erratic watering can lead to water-stress and cracked fruit.

Feeding grape vines

If grapes are being grown in rich soil, nothing needs to be added. Too many nutrients can reduce or eliminate fruit production. Remember, in the plant world, it’s all about reproduction. Grapes are the reproductive part of the vine. If the plant doesn’t feel the need to reproduce, it won’t.

Assuming your soil isn’t perfectly rich, nitrogen and potassium can be added before berry set. (‘Berry set’ is when the grapes are 1/4” in diameter.) Zinc should only be added before the vines bloom. The only way to know if these additives are needed is to have your soil tested by a reputable lab.

Harvesting grapes

To reduce the chance of pest problems, harvest grapes as soon as they taste ripe. Unripe grapes will not ripen off the vine. Grape clusters should be cut, not pulled, from the vine, and then cooled after being harvested. Do not rinse grapes off before storing them. Do that just before eating.

Pests & diseases of grapes

Spider mites, aphids, mealybugs, cutworms, thrips, click beetles, leafhoppers, branch and twig borers, and ants can infest grape vines. Diseases such as Eutypa Dieback and Pierce’s Disease can infect grape vines, and powdery mildew is a common problem. Birds and rodents can also wreck havoc on your harvest. Monitor grape vines regularly for these pests and diseases to ensure timely control. Contact your local County Extension office for information specific to your region.

While grape vines take some time to become productive, an established grape vine can produce fruit for 50-100 years! Only one or two vines are needed to provide a family with an abundance of grapes.

Get yours started today!