The hardy and versatile Concord grape is one of the most popular grapes to grow in US gardens. You can eat them fresh off the vine, or make jams, jellies or wine with them, and they are commercially used to make grape juice. They better tolerate the colder weather of the northern states and are more disease resistant than some other varieties.
Mulch your vines generously each spring and keep them free of weeds.
Water grape vines infrequently, but heavily, as they have deep root systems. Don't water when the soil is moist, but when it begins to dry out.
Cut the vines back in the first year to two or three strong buds, each of which will grow into a cane. Several shoots and an abundance of leaves will grow, which will encourage the vine to develop a strong root system. In the second year, remove all but two of the strongest canes from each vine, and allow three to four shoots to grow from each.
Tie the canes to a four- or five-foot tall stake in the first year. You'll need to build a trellis to support them in the following year, as grape vines don't stand up well on their own and are prone to disease when they grow on the ground. The simplest trellis, according to the University of Minnesota (see references), is the Kniffen system: Set posts in the ground on either side of the vine, between 16 and 24 feet apart. Stretch two wires horizontally between these posts. The first should be 36 inches above the ground, and the second 60 inches. Support the vine by keeping it tied to the stake, and then to the wires as it grows.
Remove flowers when they form for the first two years--the vines are not strong enough to bear fruit. You can also thin the vines by removing some of the flower clusters in the following years.
Prune during the dormant season, beginning in the third year. Pruning prevents the vine from becoming too dense, and also allows you to control the quantity of grapes. When too many grapes develop, they will be small and may not ripen. When branches reach the wires of the trellis, either remove them or cut them back to two buds.
Concord grapes are ready for harvest some time between Labor Day and the first frost. When you think they are ready, taste them. If they are sweet and flavorful, and no longer tart or sour, the grapes are ready to pick.