How to Grow Grapes

Choose the right grape for your climate

Grapes fall into a few groups, and choosing the right one for your climate matters more than anything else you do.

• European grapes (Vitis vinifera) include most supermarket table grapes. NC State lists them for zones 6-10, but they want warm, dry summers and mild winters, and hot, humid southern summers hurt them. University of Arizona Extension recommends them below 4,500 feet in Arizona, naming ‘Thompson Seedless’, ‘Flame Seedless’, ‘Ruby Seedless’, ‘Perlette’, ‘Beauty Seedless’ and ‘Cardinal’.
• American and French hybrid grapes are the slip-skin types such as ‘Concord’ and ‘Niagara’. They are hardier than European grapes. Arizona recommends ‘Concord’, ‘Niagara’, ‘Catawba’, ‘Himrod Seedless’, ‘Reliance’ and ‘Seneca’ above 4,500 feet.
• Cold-hardy hybrids extend grapes into zones 3 and 4. University of Minnesota names ‘Somerset Seedless’ and ‘Petite Jewel’ for zone 3, but only with the canes buried each winter. ‘Magenta’, ‘Trollhaugen’ and ‘Saint Theresa’ are suggested for zone 4.
• Muscadines (Vitis rotundifolia) are native to the Southeast, and NC State lists them for zones 5-9. They resist Pierce’s disease, the bacterial disease that keeps European grapes out of Florida. UF/IFAS says homeowners can grow them without spraying.

Good muscadines for fresh eating in Florida, per UF/IFAS, include ‘Fry’, ‘Summit’, ‘Supreme’, ‘Black Beauty’ and ‘Pam’, which are all female and need a pollinator, plus self-fertile ‘Triumph’, ‘Tara’, ‘Polyanna’ and ‘Granny Val’. For juice and wine, UF names ‘Carlos’, ‘Noble’, ‘Welder’ and ‘Alachua’. If you plant female cultivars, put a self-fertile vine nearby.

Site and soil

Grapes need full sun, and good air movement keeps disease down. Arizona wants soil at least 2 feet deep, since roots can reach 3 to 4 feet, and warns against heavy clay, shallow caliche and very alkaline soil. Avoid low spots where cold air settles. Muscadines prefer a pH of 5.5 to 6.5 (UF/IFAS).

One warning matters everywhere. Grapes are extremely sensitive to the lawn herbicide 2,4-D. Illinois Extension says drift can travel half a mile to a mile, and Arizona says gardeners who use it near leafed-out vines may find grapes impossible to grow. Keep it, and any sprayer that has held it, away from your vines.

Planting

Bunch grapes go in as dormant vines in early spring, once the soil can be worked. University of Arizona Extension also allows planting just after the last frost to avoid a freeze. Check the dates for your zone above. In Florida, plant bare-root muscadines while dormant, December through February. Container-grown vines can go in any time of year if you water them.

1. Keep bare roots moist. Arizona trims roots to 4 to 5 inches. Illinois cuts off only long or broken roots.
2. Set the vine slightly deeper than it grew in the nursery. On grafted vines, keep the graft union 4 to 6 inches above the soil.
3. Cut back to one shoot with two buds. It looks drastic, but it gives you one strong trunk.
4. Spacing: Illinois uses 8 feet between vines and 10 feet between rows. Arizona spaces European types 6 to 7 feet apart and American or hybrid types 8 to 9 feet. Muscadines need much more room. UF/IFAS spaces them 12 to 20 feet in the row, and one vine can cover a 6-by-15-foot arbor in three years.

Training the first two years

In year one, tie the strongest shoot to a stake and remove the rest. Build the trellis before the second season. Illinois’s four-cane Kniffin system uses wires at 3 feet and at about 5.5 to 6 feet. Arizona trains to a wire at about 42 inches with a catch wire 14 inches above it. Muscadines are usually grown on a single wire 5 to 6 feet high. The trunk is tipped at the wire so two arms, called cordons, grow out along it.

Pick off any clusters that form in the second year. Arizona’s advice is to take no crop until the third year, because fruiting too early stunts the vine.

Pruning established vines

Grapes fruit on shoots from one-year-old canes, so heavy pruning every dormant season is normal. Underpruned vines give many small clusters of small grapes and tend to bear only every other year. Overpruning just reduces the crop.

For cane-pruned bunch grapes, Arizona keeps four canes each winter, two high and two lower, with 8 to 12 buds apiece. Next to each one it leaves a renewal spur cut to two buds, and it removes everything else. Muscadines are spur-pruned instead: cut back to spurs of 2 to 4 buds spaced about every 6 inches along the cordon. UF/IFAS prunes muscadines from mid-January to mid-March, because November and December pruning can worsen winter injury.

Water and fertilizer

Arizona waters when the soil is dry 3 to 4 inches down, slowly and deeply, about every 7 to 10 days in summer, with steady moisture from bud swell through cluster set. Grapes need little fertilizer. Illinois skips it entirely on vigorous vines, because too much nitrogen gives soft growth that winter kills. Arizona starts feeding only in year three. Illinois notes that the roots are rather shallow, so cultivate no deeper than about 3 inches.

Harvest

Taste is the only reliable test. Purdue notes that most grapes color up long before they sweeten. Ripe berries soften slightly, the whitish bloom on the skin becomes more obvious, and the seeds turn from green to brown. Grapes do not ripen further once cut. Bunch grapes can keep up to about eight weeks at 32°F and high humidity. Florida muscadines ripen from late July to late September, usually need at least two pickings, and keep about a week refrigerated.

Common problems

• Birds: net the vines, or slip paper bags over clusters once they are about half grown. Bags also reduce skin splitting after heavy rain (Purdue).
• Powdery mildew: white growth on leaves. Good air flow helps, and fungicides control it on susceptible vines.
• Black rot: shriveled black berries and leaf spots. Remove mummified fruit and prunings.
• Pierce’s disease: the reason to grow muscadines rather than European grapes in Florida.
• Herbicide injury: narrow, fan-shaped, saw-toothed leaves one to three weeks after exposure to 2,4-D.