A well-maintained grapevine (Vitis spp.) can yield a healthy and hefty harvest for dozens of years. The vine is relatively simple to cultivate, and its fruits, or grapes, are nutritious. A grapevine's age -- potentially more than 40 years -- and soil quality, however, have a lot of bearing on the vine's care and maintenance. A grapevine requires modest fertilizing and watering, annual pruning and pest management.
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Step 1: Apply a Granular Fertilizer
Use a 10-10-10 granular, organic or synthetic fertilizer, but only if the grapevine requires fertilizer. Unless you grow the vine in poor-quality soil, it doesn't need fertilizer during its first year. An older grapevine in poor condition requires fertilizer. Measure 8 ounces of the 10-10-10 granular fertilizer if it is needed during the vine's first year or up to 16 ounces of the fertilizer for an old grapevine, and scatter it on the soil surface above the root zone, 1 foot from the vine's base. Fertilize in early spring before bud swell, which is when buds appear engorged and fluffy, ready for the flowers to burst open.
Fertilizers contain nitrogen, potassium and phosphorous, or N-P-K, plus secondary nutrients. Grapevine roots run deep and thrive in well-balanced, slightly acidic to neutral soil with a pH level of 5.5 to 7.0.
Test the soil to determine its pH level. Your county's Cooperative Extension Service or a laboratory can test it. Test the pH level every two or three years. Naturally rich soil requires fertilizer only every two or three years.
Step 2: Water and Monitor Soil Moisture
Water the soil directly above your grapevine's roots with about 1 inch of water per week in the first year. After its roots become established, a grapevine needs only thorough, infrequent soakings at the root zone. A combination of rainfall throughout the year and manual watering during hot or dry periods suffices.
Monitor soil moisture by checking it with your hand at a point 2 feet below the soil surface. Squeeze the soil at that depth with your hand. Soil that clumps together doesn't require watering, but soil that breaks apart easily, or crumbles needs watering. Appropriate watering and soil moisture is essential to a healthy grapevine because overwatering causes its leaves to drop.
You can grow a grapevine in almost any part of the country. Grapevines are hardy in U.S. Department of Agriculture plant hardiness zones 2 through 10, depending on the variety.
Step 3: Prune Most of the Grapevine
Prune a dormant grapevine aggressively in fall, winter or early spring to ensure it fruits the following growing season. Don't prune a frozen, brittle vine, however. In the first year, leave three or four buds per every 1 foot of cordon, which is the "arm" or horizontal trunk of the grapevine. The second year, leave 10 buds per every 1 foot of cordon so that the following year they may grow shoots, or canes. One-year-old canes bear grape clusters.
A grapevine produces more wood than is necessary. So prune a majority of its vigorous growth each year. Remove 70 to 90 percent of the growth using the appropriate tools: pruning shears, lopping shears and a pruning saw, each of which was disinfected. Use pruning shears on 1-year-old wood and the lopping shears and saw on 2- or 3-year-old wood.
Disinfect pruning tools before and after using them to prevent the spread of plant diseases. Brush soil and other debris off the equipment. Soak the tools in a disinfectant solution that is 1 part rubbing alcohol and 1 part water for at least five minutes. Rinse them with clean water, and let them air-dry.
Step 4: Inspect and Net to Prevent Pests
Inspect the grapevine's foliage for common pests, such as:
- Japanese beetle, which has a metallic-green head and copper-colored wings.
- Multicolored Asian lady beetle, a red-orange and black insect about 1/4 to 1/3 inch long.
- Yellowjacket, a 1/2-inch, beelike insect with a smooth stinger.
- Grape berry moth, a mottled, brownish moth about 3/8 inch long.
Pick grapes as they become ripe, and remove rotted grapes and dead leaves from the ground to keep pests away. If clusters of grapes include any injured or pest-infested grapes, then remove the affected grapes by hand.
Protect your grapevine with a net to prevent birds from consuming your crop. Use bird netting, which is available at home-improvement stores. Plastic netting is simple to work with and cut. Netting mesh size and the amount of netting needed depends on the size of the grapevine and the size of the birds. Drive a series of poles into the ground around the grapevine, avoiding the vine's roots. Drape the net over the poles, ensuring the net hangs at least 6 inches above the grapevine. That distance should prevent birds from picking at grapes through the netting.