Concord grapes (Vitis labrusca) are a popular American cultivar known for their distinct, musky, or “foxy” flavor, making them a favorite for jellies, juices, and preserves. This vigorous vine is highly valued for its exceptional cold hardiness, thriving reliably across a broad range of climates, typically succeeding in USDA hardiness zones 4 through 8. Cultivating Concord grapes requires a commitment to structural training and annual dormant pruning, but the reward is a consistent, abundant harvest of deep blue-purple fruit. Establishing a productive grapevine begins with careful consideration of the planting site and proper initial placement.
Choosing the Location and Planting
The successful establishment of a Concord grape vine starts with selecting a site that provides at least six to eight hours of direct sunlight each day. Adequate sun exposure is necessary for high-quality fruit development and the initiation of next season’s flower buds. The soil must be well-drained, as grapes do not tolerate standing water, which can lead to root rot. Concord vines prefer a slightly acidic soil pH, ideally ranging between 5.0 and 6.5.
Planting should occur in the early spring while the vine is still dormant. Dig a hole wide enough to accommodate the fully spread root system. Backfill the hole with soil, ensuring the graft union, if present, remains above the soil line. If planting multiple vines, space them approximately six to eight feet apart to allow for proper air circulation and growth.
Thoroughly watering the newly planted vine settles the soil around the roots and eliminates air pockets. Avoid adding fertilizer directly into the planting hole, as this can burn the young roots. Focus on providing consistent moisture until the vine is established to encourage deep root growth.
Training the Grapevine Structure
Grapevines require a permanent support system like a sturdy trellis or arbor, as they cannot support the weight of their own foliage and fruit. The structural support should be in place before planting, often consisting of a simple two-wire trellis system. The goal in the first two years is to train a single, straight trunk that will form the permanent vertical structure of the vine.
During the first growing season, select the strongest shoot to become the trunk, tying it loosely to the support, and remove all other competing shoots. Once the main trunk reaches the desired height, it is cut back to encourage the development of two permanent horizontal arms, known as cordons. These cordons are trained and tied horizontally along the support wire, forming the vine’s permanent T-shaped framework.
This permanent structure is crucial because the fruit-bearing canes will emerge from these cordons each year. Systems like the high-wire cordon or the Geneva Double Curtain provide excellent fruit exposure and canopy management for Concord grapes. The permanent wood of the trunk and cordons should remain largely untouched by annual pruning.
Yearly Pruning and Maintenance
Proper dormant pruning, performed in late winter or early spring before the buds swell, is the most important annual task for Concord grapes. Fruit develops only on new shoots that grow from one-year-old wood. Concord grapes are primarily managed using the cane pruning method, which involves removing about 90% of the previous year’s growth to maintain vine balance and fruit quality.
To execute cane pruning, select four to six healthy, pencil-thick canes from the previous season, and cut each back to leave 8 to 12 buds per cane. These selected canes are tied to the trellis wires and produce the current season’s crop. All other one-year-old canes are removed entirely, except for a few selected renewal spurs, which are cut back to only two buds. These spurs are positioned close to the cordon and produce the vigorous canes needed for the following year’s harvest.
The “30 + 10” rule is often used for a balanced approach: thirty buds are left for the first pound of prunings removed, and ten buds are left for every subsequent pound. Throughout the growing season, maintenance involves deep watering, providing about one inch of water per week during dry periods. Applying a balanced fertilizer in early spring supports healthy growth, but excessive fertilization should be avoided as it encourages leafy growth over fruit production.
Pest and Disease Management
Managing pests and diseases relies heavily on preventative cultural practices that encourage a healthy environment for the vines. Good air circulation, achieved through proper training and strategic leaf removal, is a primary defense against fungal infections. Common fungal issues include black rot and powdery mildew; black rot appears as reddish-brown spots on leaves and later develops into hard, shriveled fruit known as mummies.
Powdery mildew presents as a grayish-white, dusty growth on leaves and berries. It can be managed with organic fungicides like sulfur or potassium bicarbonate, applied early in the season. Sanitation is also important, requiring the removal and destruction of all infected plant debris and fruit mummies that harbor diseases over the winter.
Insect pests like the grape berry moth lay eggs on developing fruit, where the larvae burrow and cause damage. For insect control, integrated pest management strategies are preferred, including the use of pheromone traps to disrupt mating cycles. Japanese beetles are common defoliators, and small infestations can be managed by handpicking the adult beetles in the early morning.
Harvesting and Using Concord Grapes
Concord grapes typically ripen in the late summer or early fall, often around September, depending on the growing region’s climate. Determining the correct time for harvest is crucial, as grapes do not continue to ripen or increase in sweetness once picked. While the deep blue-purple color is an indicator, the fruit may color up to two or three weeks before peak flavor is achieved.
The most reliable way to confirm ripeness is by tasting the fruit, looking for a balance of sweetness that overcomes the initial tartness. The seeds inside a ripe grape will have turned from green to a light brown color, and the berries should separate easily from the stem. When harvesting, use sharp shears to cut the entire cluster from the vine, rather than pulling individual grapes.
Once harvested, the grapes can be stored in the refrigerator for several weeks, though they are often immediately processed due to their delicate, slip-skin nature. Concord grapes are primarily used for making homemade jellies, jams, the iconic purple grape juice, and occasionally American-style wine. Their strong flavor and high pectin content make them excellent for these culinary purposes.