Traditionally, the states east of New York State comprise the region known as New England. Grapes (Vitis spp.) grow well in this region with cold winters and cool to warm summers, but choosing an appropriate and hardy grape cultivar (variety) is key to success. Regardless of which state in New England your garden is in, grapevines relish a full-sun exposure in a fertile, well-drained soil. Avoid shady sites, soggy soils and areas that pool cold air and frosts such as in the basin in a valley or bottom of a hill. New England expands U.S. Department of Agriculture hardiness zones 3b to 6b, even warmer nearest Martha's Vineyard.
Plant the grape in a garden location that basks in at least 10 hours of direct sunlight daily. The soil must be fertile and well-drained, never becoming soggy after rains. Ideally, the soil pH ranges needs to be between 5.3 to 6.0 according to the University of New Hampshire Extension. Add organic matter by cultivating compost, peat or cured manure into the top 12 inches before planting the grape vine. The best time to plant grapes in the cool northern New England climate is very early spring after frost leaves the ground.
Monitor the soil around the grape and water it as needed to supplement natural rainfall. Grapes need a moist soil in spring and early summer and then tolerate slightly drier soils from midsummer to fall as the fruits deeper their flavor and enlarge before fall harvest. Avoid wetting foliage if possible since it could encourage fungal diseases.
Dig two holes with a shovel or post hole-digger 10 to 15 feet apart, with the grape plant centered between the two. Insert a sturdy wooden post into the hole so that no less than 6 feet remains above the ground. Back-fill the hole to steadfast the posts upright to slightly leaning away from the grape. Tamp the soil down hard with the handle of the shovel.
Secure long lengths of heavy wire, such as 8-gauge weight, between the two posts. Two separate tiers of wire creates a trellis system for the grape vine to grow and be trained on. The lower wire runs 3 feet above the ground between the posts over the grape plant and a second higher wire at 5 or 6 feet above the ground.
Tie the strongest, longest vine of the grape plant to the top wire tiered in early spring in the second year after planting according to the University of New Hampshire Extension. Use twine to tie the vine or cane to the wire, but loose enough so that the twine doesn't bind the cane on the wire to constrict it. Additional twine ties every 3 to 5 feet should provide enough support for the cane to remain on the top wire; a tie on the cane where it intersects the lower wire also provides good support.
Allow the grape to grow without any pruning this second summer. Loosely twine new branching canes onto the wire trellis to keep them from growing across the ground. Keep weeds away from the grape plant by laying a 3- to 5-inch layer of organic mulch at the base of the vining canes. Avoid placing mulch closer than 5 inches from the cane bases to prevent rot.
Prune the grapevine the third spring and each subsequent year for the rest of the grape plant's life. Cut the grape vine back to four main horizontal branches (the cordons), tying each branch onto the two-wired trellis. When done, the grape vine resembles a T with a lower horizontal bar. Reduce the length of any side branches from this primary vine structure so only two buds remain. These buds grow new canes and flowers that yield fruits. Schedule annual spring pruning for very late winter or early spring just before the dormant buds swell and reveal new leaves. Don't worry about the excessive sap bleeding after pruning, it's natural, and branches callus and heal on their own.
Apply a slow-release granular fertilizer, such as a 10-10-10 formulation, each late April or early May. Scatter the granules evenly and broadly across the soil from the trunk outwards 5 to 10 feet, roughly the same distance as the spread of the vines. The University of New Hampshire Extension mentions about 1/3 pound of fertilizer per plant when the grape vine is one or two years old, and then incrementally each year thereafter to get it up to 1 pound of fertilizer for each plant by age 4 or 5.
Cut off the twine ties from the trellis to lay the grapevine canes on the ground to overwinter in especially cold, windy winter areas of New England. This is optional but done after the grape leaves drop off in autumn. Loosely group the vines on the soil under the trellis and lay 10 to 18 inches of straw or other coarse mulch atop the canes to insulate them from winter cold. Place bricks or other items atop the mulch to prevent wind or snow from dislodging the protective mulch from the canes. Remove the mulch altogether in late winter, exposing the canes to light and air to warm up, tie the canes to the trellis again with twine. Conduct annual pruning again once the buds begin to swell for the new growing season.