Training Methods for Thompson Seedless Grapes

Four-Cane Kniffin System

• Kniffin system trellises resemble smooth wire fences strung between posts that are 2 and 4 feet high. Training the grape vine is somewhat complicated. At planting, prune the plant back to one cane with two buds. If the plant reaches the bottom wire during the first year, tie it tautly to the wire. Remove most shoots that emerge when they reach 1 inch, leaving no more than the three best near the wire. At the beginning of the second year, remove all but the most vigorous cane. Cut that cane at the height of the top wire and tie it there. Remove most of the shoots once they reach 1 to 3 inches, leaving only three or four near each wire.

Kniffin System - Years Three and Four

• By the beginning of the third year in the Kniffin system, Thompson seedless grape plants should resemble a mature grape vine, with a main truck and several canes. Remove all but two of the best canes -- ideally one on each side of the trunk -- at each wire level. Cut those back to the first four buds. At the beginning of the fourth year, you're ready to produce a real fruit crop. Prepare your grapevine by selecting a fruiting cane from each of the four directions you've trained your vine. Remove all the rest, leaving only small renewal spurs that will become the fruiting cane for the following year.

Curtain or Cordon Systems

• In a curtain system, the vine is trained to grow tall and run across a single wire that is 4 to 5 feet from the ground. Using a curtain system, grapes can also be trained in tandem, creating a double curtain. Head your grape vine back to two vigorous canes once it is tall enough to reach the wire. Tie one cane to the wire on either side of the trunk and allow them to grow. The following winter, prune the cordons so that spurs occur every six inches along the wire.

Fan System

• If space is at a premium, you can use a fan system to train your Thompson seedless grapes up a wall or fence. Begin by pruning the grapevine back to one two-bud spur. Allow it to grow unhindered the first season. In the winter after the first season, remove all but the first three or four buds on the two canes. At the beginning of the third season, remove all but the best four canes and up to three two-bud spurs set low on the plant. Now is the time to trim the canes back to the height of your trellis or fence and tie them at the top. Canes should be at an angle to one another, creating a fan-like appearance.

Arbors

• Grapes can also be trained on arbors or trellises. When trained in this way, they will not achieve optimal production, but if your goal is edible landscaping, grapes are a beautiful option. If using an arbor, train one plant up each side, pruning for a single trunk on each plant. Tie the trunk to the arbor as it grows and select canes that are two to three feet apart. Keep the canes pruned short; no more than five or six buds per cane will promote the best trunk development.