Growing Backyard Grapes in the Puget Sound Region
By Jim Taylor
The following is Jim Taylor’s answer to questions asked him while working in the WWFRF Fruit Garden and ideas from his work in Oregon where he established approximately 60 acres of wine grapes.
Are you going to grow wine grapes, vitis vinifera, or table grapes, vitis labrusca? If you want to grow wine grapes, only the earliest ripening cultivars are suitable. For best results vinifera plants should be grafted to a root stock that will encourage earlier ripening than if planted on its own roots. See the referenced literature for more specifics. Purchase only certified disease free vines. A plant with a virus cannot be cured.
Where on your property is the best place to plant your vines? The warmest full sun spot with good soil drainage available is the best place. Heavy clay soil is not desirable. South and west slopes will gather the most heat. A warm area can be created with a concrete wall. Planting on a mound, and surrounding the plant with stones will increase the temperature near the plant roots. Black plastic on the ground will also serve as a heat gathering method as well as help with weed control, but take care because if there are voles in the area, they will like the plastic shelter. Deer will also eat the plants. A seven to eight foot fence will be required if deer are in the neighborhood. Wind breaks that do not shade the vines are also helpful. Ideally the ground for your vines will be cultivated the year before planting and be weed free. You will have corrected any soil nutritional deficiencies.
Plan your spacing and your trellising. Plants can be 4 to 6 feet apart. A north-south row is best, or if your hill side is steep, plant up and down the hill. On a hill, tractors love to slide down between the plants in the row. Leave enough space between rows to accommodate equipment if you will be using equipment. In any case rows should be far enough apart, 8 or 9 feet, so that the 6 foot high vegetation will not shade the adjacent row except early and late in the day.
How should I plant the vines? Trim roots back to 4 to 6 inches and be sure the roots point downwards in the hole you have dug. If the vine is grafted, be sure the graft is above the ground level so that it can not grow roots. Prune the plant back to the largest cane, which in turn should be pruned back to two or three buds. A shield, like an opened cardboard two quart milk carton, will protect the plant from wind, small animals and keep the new growth off the ground making weeding easier. During the first season do not prune of any growing branches; let everything grow but nip off any developing fruit clusters. Mildew is not a problem.
NO GRASS. Weed competition, especially grass, is the worst thing to allow to happen in the first growing season. Irrigate, if possible, as the season demands.
First winter. Place stakes for the trellising. The ground is soft. In late winter, after the likelihood of a hard freeze is past, remove the weakest canes from the plant. Cut back to two buds on the strongest cane. From one of these buds a shoot will grow to become the trunk.
Second year training. The objective for the second season is to create a straight trunk to what will become the head of the plant. After the shoots have grown a foot or more, remove all but the longest, straightest shoot. If the plant is by a stake, loosely tie the selected shoot to the stake. If the plant is not already next to a stake, use a 4 foot bamboo stake to loosely tie the selected shoot, which will become the future trunk.
Remove any fruit clusters but do not remove the leaves and laterals (side branches) on the shoot. By this time you should have decided how you wish to train your plant. Shoots want to grow upward, they are difficult to train downward. Eventually you will want a vertical curtain of shoots above the wire. For easier pruning and harvesting the lowest wire should be near waist height. When and if the shoot reaches pencil size at the wire, cut the shoot above the first bud below the wire. This will promote new shoot lateral growth at the height of the wire. Mildew is still not a problem this year.
Second winter. If the shoot for the trunk did not grow to pencil diameter the previous year, cut the cane back to two buds. If the plant grew lateral canes the previous year and the lateral canes have grown to pencil size, cut off the weaker growth at the point where it becomes less than pencil sized and cut off the laterals from the cane. .
Cane pruning verses cordon pruning. To understand the following terminology, see page 2 of OSU’s GROWING TABLE GRAPES, “how grape plants grow”. The backyard grower, with few plants to tend, can choose cane pruning, as he is not dependent on unskilled labor for pruning. To create fruiting shoots, each year the cane pruner selects a cane growing from each side of the head of the plant and cuts off all other canes. On mature plants the selected cane is cut at the distance from the head so as to meet the cane from the adjacent plant. Younger or weaker plants can have canes pruned back to where they are pencil size. These are judgment calls. With cordon pruning permanent “arms”, or cordons, are trained along the wire.
Advantages of cane pruning are: First, there are buds on the cane that are not close to the head. In cordon pruning the shoots originate from a few buds close to the cordon. These buds, formed early in a sunless growing season, may not have had the warmth needed to develop fruitful buds. Also American grape plants may not have fruitful buds close to the cordon. Second, the cordon may not have the proper spacing of buds for optimum distance between shoots. This condition persists until the cordon is replaced. Third, there is the tendency for a strong shoot to grow at the end of the cordon, called apical dominance; this growth is not much good for anything. With cane pruning, dominance is transferred from the tip (or apex) by arching the cane over a wire perhaps 12 to 18 inches higher than the wire at the head of the plant allowing the middle part to be higher than the tip. This causes shoot growth to be more evenly distributed along the cane.
When the shoots are long enough to reach a wire another 18 inches above the arching wire move the shoots behind the wire to create a narrow vertical wall of foliage with the shoots weaving upwards back and forth through the wires of the trellis. A leaf without full exposure to the sun is 90 percent less efficient than one fully exposed. A wire 6 feet above the ground, at the top of the trellis, will be the next training wire (a total of 4 wires). Growth above this wire can be removed. A rule of thumb is that each shoot should support about 14 leaves.
Get used to heavy pruning; as the plants mature, you may be removing up to 90 percent of the previous year’s growth.
Pests If you decide to grow your plants organically, you will have a difficult time controlling botrytis and powdery mildew. Sunshine and air circulation are two helpful non-spray methods. A curtain where most leaves are exposed to sun and leaf pulling around the fruit in late summer are good deterrents. Sulfur spray applied before powdery mildew attacks is somewhat effective. After infection it is of little use. See Washington State Extension Integrated Pest Management Program for details.
GENERAL VITICULTURE, AJ Winkler et all, 1974, dated classic.
SUCCESSFUL GRAPE GROWING IN COOLER CLIMATES Good source for plants with guide for choosing cultivar for your site characteristics, including directions for establishing planting.
A QUICK START GUIDE TO ESTABLISHING A VINEYARD IN OREGON A six page pdf slanted towards commercial vineyards.
WASHINGTON STATE ASSOCIATION OF WINE GRAPE GROWERS, VINEWISE, A self help guide to growing wine grapes