Grapes Vitis spp.

Grapes are easy to grow and can bear plentifully even in northern New England. They begin fruiting in the second or third year after planting. They are rugged and cold hardy. Our vines bear consistently every year. Although many people prefer seedless types for table use, seeded varieties can be quite enjoyable right off the vine if you don’t mind “grape nuts.” Grape seeds contain an antioxidant that is twice as powerful as vitamin C.

Most grape varieties are bred from a combination of different species, V. labrusca and V. vinifera being the most important. Labrusca is native to the eastern U.S., has a wild tart musky (foxy) flavor, and is hardy and disease resistant. Concord is the best-known of the labruscas. Vinifera, native to Europe, is extremely high quality, and is the most important wine grape in the world, but is not cold hardy and is prone to disease. V. riparia, native to North America, used as rootstock for grafted varieties and in hybridization with vinifera, is very adaptable to a wide range of soils, disease resistant and very cold hardy.

In central Maine, “very early” grapes begin ripening in mid-August, while “midseason” ripen mid-September. Late-season Concord, a standard elsewhere, does not ripen in many northern areas.

Growing Grapes

• Soil: Very well drained with moderate fertility. Every few years, fertilize liberally with granite meal. Mulch annually with hay or straw.
• Sun: Full.
• Pollination: Self-pollinating; you need only one for fruit.
• Spacing: 8–12' apart in rows 8–12' apart.
• Planting: Spread roots out in hole, planting the crown even with the soil surface. Pack soil, water and mulch well. After frost danger has passed, prune new vine back to 3–5 strong buds.
• Pruning and Trellising: There are many systems for training grapes, and all involve annual pruning to remove most growth in late spring. This aggressive pruning encourages new fruiting canes. See below for a few methods, or visit the grape resource page at UMaine Cooperative Extension at Highmoor Farm. The current vineyard standard for wire is high-tensile-strength class III galvanized steel. The gauge should be 11 to 12.5. The wire is generally sold by weight. 100 lb of 11 gauge measures about 2600'. 100 lb of 12.5 measures about 3800'.
• Optional Winter Protection: If a variety is marginally hardy in your area, you can still grow it if you take special care in winter. Remove the vine from the trellis in fall, lay it on the ground, and bury with just enough soil to cover.

  If you plan to do this, plant your new grapevine at a 45˚ angle. Train new shoots horizontally for at least one foot. Then, curve shoots upward to form a J shape. This creates a flexible hinge, allowing you to lay the vine down at the end of the season.

Training Grapes on an Arbor

Train one or more vines onto an arbor or gazebo; we have 8 vines, spaced about 10' apart. Prune each vine back to a single trunk. Encourage several permanent arms from each trunk. In late spring remove 70– 90% of the past summer’s growth. Next summer new fruiting canes will grow off the permanent arms.

Training Grapes in the Four-Arm Kniffin System

• First year: After the last danger of frost has passed, cut newly planted vines back to a single stem, 6" long with two to three buds.
• Second year: Set up two wires, 3' and 5' high, stretched between posts. Cut plant back to a single stem, 6 feet long and tie it to the top wire. Leave 4–6 buds near each wire and remove others.
• Third year: Select 8 canes, 4 for each wire, and remove the rest. Tie two canes to each wire, one in each direction. Cut these 4 canes back to 10 buds each. Cut the remaining 4 canes back to 1–2 buds each.
• Later years: In the spring, remove last year’s fruiting canes. Select eight new canes. Cut 4 of them to 10 buds each, and tie them to your wires. Cut the remaining 4 back to 2 buds each. These will produce next year’s fruiting canes. Remove all other canes. The number of buds left on the fruiting canes may be adjusted to encourage more fruit (leave more buds) or larger size (leave fewer buds).