It is not particularly difficult to grow grapes successfully, but making informed decisions at the beginning can save a lot of wasted effort. When starting to grow grapes, think about how the grapes will be used before deciding what kinds of grapes to grow. Table grapes and wine grapes are very different. Wine grapes have small, seedy berries, so they are not really suitable for eating. Table grapes have a relatively low sugar level and acid level, so they don't make good wine.
Consider both local growing conditions and the type of grape before choosing which grapevines to plant. To grow grapes successfully, match the ripening habits of the grape variety to the local climate. Grapes can be grown in locations with surprisingly a short growing season if early maturing varieties are planted. Late-maturing varieties need around 170 growing days to ripen properly.
Think about the growth habits of the vines when preparing to grow grapes and provide the appropriate trellis or support system. Concord grapes droop downward as they grow, so the vines must be trained along a high trellis that gives them plenty of room to droop down during the growing season. Vinifera grapes have an upward growth habit, so they can be trained on low supports that give them room to grow upwards. Positioning the vines to accommodate their natural growth habits maximizes exposure to sunshine, which increases the amount of grapes that are formed and provides the best conditions for ripening.
Grapevines generally grow well when positioned in full sun and planted in lightweight soil. They need ample water, but they also require good drainage, so they are often planted on hillsides. They have extensive root systems, so preparing the soil to a depth of as much as 36 inches (91 cm) before planting is a good way to grow grapes. Remember that grapevines do not usually produce fruit until at least two years after planting, and some varieties require as much as four years.
Grapevines should be pruned annually to encourage them to grow grapes. Pruning should take place in late winter or very early spring, before the vine starts growing for the season. Prune out any vines that were damaged by the winter weather. Trim off any shoots growing out to the side, because lateral shoots are usually not very fruitful. Cut away enough of the vine to allow sunlight and air to reach every part of the vine. Overgrown vines are more susceptible to mildew and fungus, and they do not fruit as well. Long runners can be pruned at midseason if the vine is becoming overgrown.
Protect the grapevines from pests. Organic pesticides will deter insects. It is often necessary to cover the vines with netting as the grapes ripen, to keep birds from eating them before they are ready to harvest.
Many people who grow grapes harvest them too early. Grapes change color several weeks before they are fully ripe, so harvesting them at that point has disappointing results. Investing in a refractometer to check the sugar level of the grapes is the most reliable way to tell if they are really ready to harvest. Table grapes can be harvested when they have about 18 percent sugar content. Wine grapes usually need about 24 percent sugar content to create the proper alcohol in the wine. Using a refractometer will make sure all the work needed to grow grapes is not wasted.