How to Prune Table Grapes

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.

This picture was taken in the spring of 2012, about the second week of March. You can see a grape spur in the upper right quadrant of the picture, reddish brown, that has two leaves coming from buds . It was cut back from a much longer stem, which grew in 2011, following the directions in this posting. Since this grape can be spur pruned, I cut this longer stem back so that only two buds remains on the spur. Those buds gave rise to the leaves you see. Also coming from these buds will be growth that will form the grape clusters or bunches. Follow this spur back to its base and you will see it connected to a short stem, brown in color, older than the spur. This was the previous year’s spur. At the base is even older wood which has a characteristic greyish color.

A. If you continue to cut off all of last year’s (2011)
vine growth, you will never have grapes. Bunches of grapes produced in 2012
come from buds on growth that was produced in 2011, the previous year. The only
thing you have to do now is decide how much of the growth produced in 2012 you
will leave remaining after you have finished pruning. By the way, I usually
delay the final pruning of grapes until at least mid-February to avoid loss of
fruit from late freezes.



Another spur which has been cut intentionally too long. If there is damage from winter cold and the end of the spur dies, there is enough of the spur left for it to recover. The oldest growth at the bottom is grey. The spur on top is reddish brown. In between is a former spur which is brown. The spur has three buds. Bottom bud is pointy on the bottom right of the spur. The next bud up is on the left side where a side shoot has been cut back. The third bud is on the top right where another side shoot was cut back. After cold weather has passed at the mid to end of February you would cut the spur 1/4 inch above the second bud. After you get some experience, cut it back 1/4 inch above the bottom bud leaving only one bud.

            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.



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.

            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.

            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.



Another picture of one year old wood that will be cut back to either a spur or a cane. Canes are just long spurs. Grapes like Thompson Seedless have buds at the base of the new growth that will not produce grapes, just leaves. So in the case of Thompson Seedless we have to cut their “spurs” extra long so we include buds that will have fruit. Spurs are cut long enough so that the buds that produce fruit (usually after the bottom ten buds) are included. These extra long spurs are called “canes”.

            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.