About 4 years ago, we bought a grapevine and planted it in a nice rustic half-barrel, surrounded by a variety of herbs. It was a Thompson seedless — yum — and with “grape expectations”, we watched it grow… and grow… and grow!
The original arrangement — grape surrounded by mint, thyme, sage, rosemary, chives, I think there was some basil in there too — looked lovely at planting time. But as that grape vine grew, it lost its pretty, balanced shape and was no longer a fine anchor at the center of the arrangement. I also found that it was not easy getting the half-barrel pot watered evenly and thoroughly. Though care had been taken to ensure adequate drainage, that huge pot stayed pretty wet. Not a great situation, and the bottom line was — no grapes. I could deal with a big droopy vine, but grapelessness was unacceptable! (It does take a few years for a new vine to reliably set fruit — but I wasn’t inclined to wait and see — and had a new, better idea…)
So when winter came and the grapevine went dormant, we dug it out and replanted it at the base of a big new trellis archway. The trellis came from Armstrong Gardens in Carlsbad — strong, but light, and scaled just right. This created an archway entrance to our little garden. That grape vine loved having its roots in terra firma, and over the next few years climbed up, around, above and beyond that trellis! Each winter we’d snip off any vining branches that chose not to follow the trellis’ shape; the more we cut, the more robust the rest of the plant. It wasn’t until this year, though, that we finally figured out how and when to prune to encourage maximum fruit.
Here’s how to prune a grapevine, for shape and for fruit:
Prune the vine back hard in the winter, when it’s dormant and leafless, leaving just a few long branches that go where you want them to go;
In the spring, let the new vines emerge and watch for them to bud. Once buds appear, prune away any additional vine that grows above the fruit.
Then, start cutting off any vines that grow more than a few feet long without giving rise to buds. Cut them off right at their bases.
As the spring / summer progress, the grape buds will flower, and grapes will begin to grow. Once the grapes are set (by mid-May around here) remove all new vines and tendrils. Remove any additional growth beyond the growing grapes. This will channel as much of the plant’s energy into fruit growing as possible.
If you don’t prune at this point, the grapevine may continue budding. However, buds that appear too late won’t mature in time. Grapevines have their own internal clock, they don’t produce year-round like many other perennials do here in San Diego. At least, this has been our experience.
This is a very simple, but adequate-for-backyard-grower-purposes approach to pruning grapes — a pastime which has been refined to an absolute art by grape growers, over the millennia, around the world.
By the way, there’s a reason the Thompson seedless grape cultivar is the most widely grown grape in the world. The grapes are delicious, thin skinned and of course, seedless; and now that we’ve got that plant planted in the ground (and our pruning system down), it is producing lots of grapes. I’m pretty sure the kids have tasted some immature (very sour) grapes already; but the grown-ups are content to taste them with their eyes, until harvest time.