Summer Grape

Size, growth and what to expect

Summer grape grows fast, nearly three feet a year in our growth estimator, and a vine can live close to a century. It climbs 25 to 70 feet into the treetops by its tendrils or sprawls over low trees and shrubs. Old trunks reach 6 inches across, with bark that peels in long strips.

Small, fragrant, yellow-green flowers open in May and June, and the flowering lasts only about a week. Clusters of blue-black grapes with a whitish waxy coat, a quarter to half an inch across, ripen from August into October, and many hang on into November. They range from tart to sweet, with 2 to 4 seeds each. More than 80 kinds of birds and mammals eat them, from wild turkeys and grouse to black bears and raccoons.

It grows wild from southern Maine and Ontario west to Minnesota and Kansas, and south to Florida and Texas. Unlike our riverbank grape of stream banks, it favors well-drained upland woods, slopes and bluffs, glades and fencerows. Iowa lists it as threatened, as do Maine and Minnesota for its northern variety.

How to grow Summer Grape

Summer grape fruits only in full sun, and a vine kept in shade may flower but seldom bears. It grows in sand, loam or clay that drains well, and once established it stands drought. Site it out of frost pockets and winter wind, on a slope facing south where you can. It climbs by tendrils, so give it a sturdy arbor, fence or trellis. Keep it off ornamental trees and shrubs, which it can smother or kill. Set the support 6 feet from a wall, and set vines 12 feet apart along it. It burns readily, so where wildfire is a risk keep it out of the planting zone next to a house. It climbs whatever it reaches, so keep it more than 50 feet from overhead wires.

Saplings ship bare-root or potted. Plant them dormant, from leaf fall until bud swell, in a hole wider than the roots and no deeper. Set the crown at the soil line, put the native soil back in, and keep the mulch clear of the stem. Tie the first shoots to the support until the tendrils take hold. Strip the ripe grapes, and wash the seed clean of the pulp. For a spring sowing, hold the seed damp in the refrigerator for 3 to 4 months first. Seedlings vary and do not come true to a named variety such as 'Norton', which is grown from cuttings.

Water weekly through the first summer if rain is short. Cut it back as needed to keep it on its support, since it spreads into places it is not wanted. Deer browse the leaves in spring and summer, so cage young vines where deer are many.

Vines are male or female, and only females bear grapes, so plant three or more seedlings for a male and a female. Bumblebees carry the pollen. A vine in full sun bears its first grapes about 3 years after planting. Black rot and the grape curculio cut the crop. Downy and powdery mildew, crown gall, Japanese beetles and grape berry moths also turn up. Moonseed, a poisonous look-alike, climbs without tendrils, has leaves with no teeth, and holds one crescent-shaped seed in each berry. Other vines with similar fruit are poisonous too, so be sure of the plant before eating its grapes.