Sunday, March 23, 2014

Grape Pruning

This is the year to figure out how to prune our Concord grapes. Despite my concern last year that there were too many bunches of grapes for proper development, a lot did mature and I processed more than 70 pounds of prepared grapes. That is a lot of grapes to squeeze to separate the insides (pulp and seeds) from the skin. Except for the seeds, the rest is used. There are still jars of frozen processed grapes in our freezer even though we have already enjoyed an abundance of grape pies throughout the winter. Not to mention the jam and the grape juice.

Nonetheless, the grape arbor is an unruly tangle of vines of various sizes crossing each other at various angles, the newer ones mostly heading from north to south. (The vines were planted on the north side of the arbor.)

I know the basic drill, which is to find last year's new growth and cut those canes back to leave three buds per cane. The buds will develop into the new grape bunches. But I don't want as many bunches as last year. The bunches did not fully develop. That is, while many of the grapes in each bunch developed into nice purple grapes, quite a few others didn't. And the grapes seemed smaller. I want fewer bunches but completely formed and ripened bunches of large grapes. My goal is 80 to 100 bunches. That would mean pruning back to 30 to 35 pruned canes since three buds are left on each cane.

It occurred to me that instead of trying to start with the new growth I should go back to the two original plants (planted in 2009) and see what is growing from them (presumably in 2009 and 2010). Then follow each of these "secondary" vines and see what grew off of those, and so on. Sort of create a map of each vine. That way I can try to divide up the canes I prune this year somewhat equally among the vines they come from.

So far, trudging out into the snow of this winter, I find that each of the two plants divides into two vines at the top. Originally these vines were trained along a wire about six feet above the ground. I suspect that each of these vines was supposed to run so that one from each plant met one from other plants in the middle and the remaining vines going in the opposite direction would continue to the end of the structure. That would provide a vine covering the whole length of the wire, like two big Ts next to each other. Each plant also has a lower vine that goes along a lower wire that was part of the original structure. I suspect those vines could be removed because very few, if any, grapes develop there. But I will leave them this year to see.

All might have been fine if I had not decided to build an arbor early in 2012, I believe, so that the grapes could grow over the path next to where they were growing. But I did and I basically abandoned the wire structure (although it is still there). Then I started encouraging the new growth to go over the arbor. In 2011 all of the grapes harvested (25 lbs) were to what would be the north side of the arbor. In 2012 presumably because of the same conditions that wiped out the apple and pear crops, we harvested only 9 lbs of grapes and they also came from off the north side of the arbor . But then came the gangbuster crop of 2013. The grapes were pretty equally divided between the north side, the arbor itself, and the south side, though somewhat heavier on the south side. That means that I should be able to find some of last year's growth all over the arbor and be able to prune so that I get grapes again this year from all parts of the arbor.

Now it is time to read what I have accumulated earlier about pruning grapes and see if I can figure out the one question that has bothered me for several years. It seems to me that new growth and each year's grapes will continually be farther along the vine than the year before since the grapes are on the prior year's growth, which was on the growth of the year before that, etc. How do I get new "spurs" to form that will be the basis of next year's new growth?

On the Our Edible Garden webpage for grapes I wrote about last year's fruiting canes, which are to be removed, and last year's new shoots, which is where this year's grapes will grow. Obviously I didn't look to see what these were during the year.