Greenhouse grapes

[devonuk]

Might be Black Hamburg. Anyway they have looked like this for weeks - some ripened weeks ago, most not. The few ripe ones are delicious, the rest have stubbornly refused to do anything. Vine is about 5 years old. Would thinning the bunches, or individual grapes within bunches, encourage more even ripening?

[greenishfing]

I don't think so this late in the season? How many bunches did the vine have originally? Did you thin the grapes in the bunches when they were small?
I just had one bunch that didn't ripen. It was a bunch that formed much later than the others that was hiding at the back.

[devonuk]

I meant next year - have written off this.

I reduced the bunches from ?20 to ?10 (still a lot on a 6 ft vine), didn't thin within bunches at all.

[greenishfing]

They say reduce to 1 bunch per linear foot. I've never managed to reduce them that much. But I do thin the grapes in the bunches when they are about the size of a sweet pea seed. Even when I think I have thinned them really well the grapes in thebunches still look too tight (but bigger). Any bunches that come later I try and remove.



This picture was taken Sept 13th when they were nearly ready.

[devonuk]

Thank you. I think fruit thinning may be the key.

[Thelma Sanders]

I only allow one bunch to form on every other one of this year's new shoots, pruning all the other bunches off. There only seems about 8 ins between each new shoot, on my vine, and I think a bunch on every new shoot would just be too many.
Also, once the bunches have set and are beginning to fill out, I cut off all the grapes in the bunch that are smaller than the average. They never seem to catch up anyway!

[Deltawhiskey]

Some people say the the fruiting canes should be cut back to two or three leaves past the bunch. Do not do this. The better informed suggest that to ripen each fruiting cane needs twelve to fifteen leaves after the bunch.