Pruning Thompson Grapes
Pruning your Thompson Seedless grape vine is easy, IF you know what you are doing!
Thompson Seedless is, what we grape growers call it, unfruitful. This means that a Thompson don’t produce grapes from bud 1 to 6 on a shoot. Now, you might think: “My Thompson bears grapes on those buds!”. Yes, that is true, as this is NO rule of thumb, but it is a known fact that the fruit-bearing buds on a Thompson are between bud 8 to 14 (counting from the basilar bud on the shoot).
Normally, you prune the most of the wine grape and table grape varieties, with spurs (3 buds), but in the case of Thompson’s, you will have to cane prune (pruning with long bearers).
It is very important to prune a spur for every cane you prune. This spur is called a renewal spur, and the only reason we prune a renewal spur, is to renew the grape vine next year.
Now this might be a bit vague, trying to explain in words, so I have added some pictures found in the Complete Grape Growers Guide.
If your grape vine was pruned last year, your canes will look something link this. Notice the renewal spur on the frame of the vine. This will stay a spur until you need to use it for renewing the vine. This normally happens when the first few buds on cane of an unfruitful variety (like Thompson’s and Crimson Seedless) does not shoot (sprout).
The following sequence of images will show you how to cane prune your Thompson vine
(Sorry for the quality, but blogger blurs the images when I try to enlarge them, the quality in the
Complete Grape Growers Guide is much better)
Notice how I have removed part of the “framework” of the vine. Next year, the spur will have two sprouts again (remember, you pruned the spur with 2 buds) and the cane will have lots of side shoots again (looking like the first picture).
The whole process starts again!
With a Thompson grape vine, you must choose the canes you will use for your bearers carefully. Those thick, flat-looking canes, with long inter-nodes are normally more unfruitful than canes the diameter of your ring finger (or a bit thicker than a pencil). Choosing the wrong canes, will result in an lower yield, and you will not have enough “wood” next year to choose from when you prune.
I think you realise by now, that if you have pruned your grape vine the correct way last year, the pruning effort this year, will be much easier, ESPECIALLY when cane pruning (like Thompson Seedless).
Some hints when you prune
- Take time to look over the vine before you start
- Pick out several well-placed canes that look like good prospects.
- Cut out old wood and canes that are obviously unsuitable – canes that are small and weak, or too far out from the main trunk. This will clear up some of the confusion as you go.
- Always leave at least one alternative cane until the last, in case you break one.
- Bend canes gradually into place before tying. Canes that grow in a direction other than where you want them can often be persuaded to cooperate by cracking them gently. Use both hands to bend the cane at the point where you want it to change direction, and apply pressure just until you hear the fibers crack.
Now this is only an overview of how to prune Thompson Seedless and other unfruitful variates. The Complete Grape Growers Guide goes much deeper into the science of pruning your grape vine.
Have a grape (great) day my friend
“The Grape Guy”
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