The tender grape

3 June 2009

In The Garden With the Fluvanna Master Gardeners
By Irene C. Burke - Fluvanna Master Gardener
Fluvanna County Extension Office: 434.591.1950

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A gentle reader and avid gardener wants to try her hand at growing table grapes. With the abundance of vineyards in central Virginia she figures she stands a chance. The prospect, however, of wading through dense text and web-based information is forbidding. Lets see if we can untangle this subject for her and you.

As a beginner she has made a good choice by opting for small fruits over tree fruits. Space requirements and pest control are more manageable and the fruits of her labors will be evident in three years, lasting 25 to 30 years.

With care and attention to these key elements, success is within reach: Site, and variety selection, soil, pruning, and integrated pest management.

For central Virginia, American bunch grapes are the best options. Look for resistance to black rot, powdery and downy mildew, cold hardiness for those occasional tough winters, vigor and abundance, and sweet flavor, with juice, jam and jelly possibilities. This narrows the selections to the blue-black Concord and Steuben, the golden-yellow Himrod, and the dark blue Mars Seedless.

Choose reputable growers, who guarantee quality and label accuracy, use correct wrapping and packing, and offer vines for planting in early March, three or four weeks before May 1-15, the last frosts average date. Whether ordering online or from a local nursery, select year-old plants and always inspect the roots and vine for health.

Under optimum conditions, grapes roots anchor themselves in the soil often to a depth of six to eight feet. Though Virginias piedmont clay may be a challenge, its structure and fertility can be deeply improved at least 24" with organic matter at a one-to-one ratio in an 8 X 10 bed maintained by a six-inch mulch of aged compost or arborist wood chips for each vine.

Prepare for generous spacing, which will prevent disease, encourage vigor and assure higher yield. Most small gardens can support one to two vines trained along a fence, over an arbor or up a trellis in full sun, sheltered from the westerly wind, above frost pockets and wet areas.

Now is a good time to prepare for next years planting. For the year-old vine, use an inch or two of leaf mold, thick with white thready mycorrhizae fungi to encourage the uptake of phosphorus and promote strong root growth. For mature vines work in a quarter inch of coffee grounds mid-spring to support lush vines with the released nitrogen. Grapes tolerate a wide range of soil pH, but prefer and thrive with 6.0 to 6.8.

Pruning and training grape vines to a trellis or arbor requires a three-year process of shaping the vine to a structure using the four-arm Kniffin system. Important detailed instructions are found in the VCE Publication Number 426-840 or online at the VCE web site >Resources >Fruits & Vegetables > Fruits-Home Gardening >Small Fruit in the Home Garden.

Harvest bunch grapes when fully ripe, as flavor and sugar dont improve after harvesting. Use the fruit immediately, cutting each bunch from the vine with a sharp knife or shears to avoid damage.

Tip of the Week

Evolutionary biologist, Marco Archetti reported online, April 14 in the "Proceedings of the Royal Society B" that those life-sucking insects that plague our gardens, those aphids who fed on apple trees with red autumn foliage were less vigorous and often failed to reach maturity. Though aphids don't see red, there is something about red leaves that doesn't suit them.