|We have Concord and Thompson Seedless grapes growing on an arbor; they are quite old and need serious pruning. How do I prune and fertilize them?|
|Grape pruning can be intimidating, especially if the plants have been allowed to become unruly. First rule to remember is that grape production comes from flower buds that formed on the previous summer's growth. So, if you leave some of last year's growth, you should have fruit the next summer.
Start pruning by cutting off any unneeded canes. Then selectively cut back the growth left on the trellis or support by looking at the cane from the bottom up and counting at least 25 buds (or nodes where last year's leaves grew). Cut off any growth beyond the 25 buds. This is not a scientific approach, but it is practical, and following it you should be able to reduce the volume of canes without losing all of your next year's crop.
Your grape plants shouldn't be fertilized until spring, after they've begun to grow. Take care not to apply too much nitrogen or you'll have lush, green growth at the expense of fruit production. Use about 4 tablespoonfuls of 8-8-8 and broadcast it over 100 square feet of soil near the base of your grape plants. Or you can spread a 2" layer of compost over the same area.