Poor Grape Production Maybe Not Fertilizer

Q. What type of fertilizer do you suggest for table grapes. Mine have been in ground 3 years now and the production has been less than I hoped. I have been using compost and worm castings twice a year.

A. The problem may not be the fertilizer or how much you are applying but how the vine is pruned. There are two general methods of pruning grapes. Some grapevines are pruned using the “spur” method while others are pruned using the “cane” method.

            Grapes that should be pruned using the cane method may produce little or no fruit if they are pruned using the spur method. However, grapes that require spur pruning WILL produce fruit if they are cane pruned. I am thinking you have a great that may require cane pruning but you spur pruned it instead.

            The difference between the two is the amount of last year’s growth left attached to the vine. In spur pruning, last year’s growth is cut back severely, leaving less than an inch remaining. In cane pruning, last year’s growth is cut back so that about eight or 10 inches of growth remains attached to the vine.

             Bottom line, if you are not sure how to prune your grapes, leave last year’s growth 8 to 10 inches long. Last year’s growth will be a different color than the older parts of the vine. Sometimes it’s reddish-brown and sometimes it’s yellowish-brown. When the fruit emerges, re-cut the cane to a better length.