Q. I have a couple of vines of grapes. Should I cut them back so the stem is about 1 ft. high? I've been doing that and have not gotten many grapes from my Thompson plant and none from my seedless Flame. These plants are about 5 years old.
Let me walk you through the steps for pruning table grapes. You can prune wine grapes this way but wine grapes should be pruned slightly different. With wine grapes we want to be more careful to “balance” the load of fruit with the growth of the vine to get better quality grapes.
I like to prune grapes in either one step in mid-February or a two-step process with an initial pruning of the grapes at leaf fall and a final pruning on the February date. Some people are itching to cut those grapes early and this will give them something to do. Otherwise just delay the pruning.
There are two things to know before you begin. First, the wood where the fruit is produced is on last year’s growth which is a different color from older, nonproductive wood. It is usually more reddish. I will post pictures on my blog next week so you and others can see what I am talking about.
Secondly, most grapes are pruned so that the amount of last year’s wood, the reddish colored wood, is only an inch or two long. But there are two table grapes that are NOT pruned like this. These are Thompson seedless and Black Monukka. These are pruned so that the remaining reddish, last year’s wood is about 12 to 18 inches long.
When you leave just a very short length of reddish wood remaining after pruning then this is called spur pruning and this short stub of red wood is called a spur. When you leave a long piece of this reddish wood, then this is called a cane and you are cane pruning.
your grapes early can possibly result in no fruit production this next year in
our climate. If there are some very low temperatures and strong, cold dry winds
blowing across your vines after you prune it is possible to freeze back the
spurs or canes and lose your crop or severely reduce it. If you delay pruning
until February, you reduce that risk.
|This is the tangle of new growth you must either remove or cut back to spurs. The new growth in the right places and spaced the right distance apart will be cut back to spurs, one or two buds in length.|
Here is how to prune. Find the end of a stem or branch of a grape vine. Follow it until you see a place where there is a definite change in color from red to grey and the wood looks older. There is a clear separation between these two colors. This is where the 2012 growth began (red) and growth in 2011 (grey and older) ended.
On the outside of the reddish stem you will see buds on either side. The last years red growth (on buds close to the separation of colors) is where the fruit will be produced for most grapes.
For those grapes that require spur pruning, you can cut the reddish stem back leaving only two buds remaining. Prune ¼ inch beyond the second bud from the grey wood with a straight cut.
For those grapes which should be cane pruned, like Thompson seedless, you should cut the red growth or cane so that there are ten buds remaining. Essentially it is just a much longer spur. This will leave a reddish cane in length something less than 18 inches.
Grape vines are notorious for bleeding after they have been cut. In other words you may see water coming from the cut ends. Don’t worry about that. It is normal and will heal.
When the vine sets small, BB-sized fruit in bunches, it is time to go ahead and remove bunches that are poorly formed or have not set berries very well or are too small.
The remaining bunches are then pinched at the bottom, removing about 1/3 of the bunch. This increases the size of the berries that are remaining in the bunch. If your berries are small, then you did not remove enough bunches or you did not pinch the bottom of the bunch enough. Both are important.