Van Bourgondien

Garden Guide Growing Great Grapes

Site Selection: Choosing the right spot for any long lived perennial plant is important. More so with grapes as the right site will help reduce disease problems and ensure fruit for many years to come. The 4 factors are: 1) Soil Drainage - grapes do not like wet feet, so avoid sites where the soil is heavy or water sits for any amount of time; 2) Air movement - Good air circulation will reduce disease problems; 3) Avoid frost pockets - plant grapes in an area where they will not be exposed to late spring frosts; 4) Sun exposure - grapes like full sun.

Soil Preparation: Since this will be the permanent home for the grape it is important to properly prepare the soil before planting. Grapes like a moderately acidic soil (between pH 5.5-6.0) so liming is not generally required unless your soil is very acidic. Grapes are not heavy feeders, but working some compost into the soil should help them get a good start.

Planting: Space grapes 8' apart in rows 10-12' apart. The soil should be lightly packed around the plant and well-watered until the grape begins to grow. They can be fertilized 3-4 weeks after they are planted with a balanced fertilizer.

Pruning: Since grapes can be very prolific and only bear fruit on 1-year-old wood, they need to be pruned and trained to bear an abundant harvest. The process below describes a common pruning method called the 4 arm Kniffen system, but the principles can be applied to any form. This system involves using galvanized steel wires spaced 3' apart on posts 16' apart. Grapes should be pruned in late winter, early spring before the buds have begun to grow.

Year 1: In the first year's growth, the grapes should be tied up to a stake and only the strongest 2 shoots allowed to grow. (Figure 1)

Figure 1

Year 2: Select the stronger of the two canes to be the main trunk of the grape. If the cane has only reached the first wire, then restrict it to shoots (Figure 2A). If it has reached the top wire, then once the shoots begin to grow, remove all but the strongest 4-5 at each wire. These will be the arms of the grape vine. (Figure 2B)

Figure 2

Year 3: At each wire, select the strongest cane going in each direction and prune to 3-4 buds in each cane. (Figure 3) These will provide the fruiting wood for the next year.

Figure 3

Year 4 and beyond: Finally the first fruiting year has arrived. Select the stronger cane at each wire and prune to 6-10 buds each. This cane will bear the grapes. Also leave one shoot in each direction pruned to 2-3 buds. This will supply next year's fruiting canes and is called a spur. The fruit should be harvested in the fall. The color will change before the grapes are ripe, so a taste test is the best way to know when they are ready. In future years, prune back the previous year's wood and select a new fruiting branch and spur.

Figure 4