We have commercial vineyards here in Coachella Valley that grow Thompson Seedless for Costco. Huge bunches with huge grapes! The grapes are on T trellis's, and have huge 2'- 2.5' cordons. From those cordons grow some pretty big canes. They Cane prune each year, and they probably thin the clusters also (not sure about that), but I see how many clusters each vine has, and it's about 15-16. The fruiting wires are filled with large dangling clusters. They keep those vines neat and concise.

You are correct. Grapes grow on new wood only. Go over to You tube and search for "cane pruning grapevines," and watch some videos. You will see the proper way to prune to get nice big bunches.

Good luck to you!

Suzi

DesertDance:

Something like this?

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Myk1, I do prune each year, and I also maintain during the growth period, but mainly just by removing the branches that are growing crazy long. However, I am not growing on any type of system (e.g. T Trellis or fruiting wires). My vine is growing and supported on the side of my wooden fence.

I will also check youtube. Thank you Suzi, and you too myk1.

Remy

Remy:

Thompson seedless are naturally small berries. What you are seeing is somewhere near the normal berry size of that cultivar. Commercial growers achieve larger berries by spraying gibberellic acid to first thin the fruit off each cluster and then to plump up the remaining berries. They also use other tricks like girdling the trunk. You could do this. It's not that hard. But it doesn't increase the flavor or sweetness and may do the opposite.

Doing a better job of pruning, thinning, and other cultural tasks can increase berry size somewhat if they are limiting factors.

Commercially berry size increase is used only for Thompsons destined for table grape use or other special applications like Jumbo raisins. The normal raisins are grown with small berries just like yours. So the vast majority of Thompsons are grown like yours with small berries.

Franktank, yes! That's the T trellis.

My grapes are only wine grapes, and we love small sweet berries for better wine, but if you're popping them, those seeds are nasties!!

Remy, you will enjoy You Tube videos! Nothing is better than a picture!

Speaking of raisins, fruitnut, they also grow red flame seedless here, and we get raisins out of big bins at the farm stands. HUGE red flame raisins. The only problem is they must be washed (dusty little things), and they are not concerned about the stems! You find lots of stems in the lb or so that you scoop out of that bin. It's not exactly Sunkist, but they are really cheap, so it's a trade off!

Suzi

Thank you all for the information. The grapes are very good, so I guess that will have to be good enough.

Thx all.

Remy

One thing you can easily do is to cluster thin. Each shoot should have 2 clusters. After the fruit has set, remove one of the clusters. Of course you will have fewer grapes, but the remaining grapes will grow larger.

Also, removing the bottom few berries in each cluster is supposed to increase the size of the remaining berries. I have tried this and it does seem to help a little. Here is a video discussing cluster thinning, shoot thinning, and pruning.

Here is a link that might be useful: Grape Thinning

My mother-in-law drinks about a vine a day :)

franktank! Are you my son in law? :-)

Have a very large grape vine which I prune back every fall and prune as it gets crazy in the late spring. I have a large amount of grapes that turn purple in bunches but only get the size of a green pea and are bitter. This is the third year they have done that. Any ideas that you can offer. I'm not sure if I'm able to get back on this site ...my email is kippvah@msn.com. Thank you