Delay Pruning Grapes in the Desert to Prevent Losses

            

Spur pruning of grape delayed until just before new growth occurs.

Whether you are growing wine grapes or table grapes, it’s a good idea in our climate to delay the final pruning until you are confident freezing, dry and windy weather has passed. The reason for this is to minimize fruit loss because of cold, windy and dry late winter and early spring weather. If you get eager and make your final pruning early, it’s possible that cold, dry windy weather later might eliminate some or all the fruit you intended to keep.

If grape pruning seems a bit daunting, go ahead and prune last years growth long (canes) even if your grape should be spur pruned. As the time approaches for new growth to occur, finish pruning with a second cutting of last years growth to the proper length. This avoids potential losses from the cold and dry winds that can sometimes happen in the desert.

All grape bunches come from buds on last year’s growth. In this way, fruit is produced much like fruit is produced by peaches and nectarines. But this is where the similarity stops. Some grape bunches (Zinfandel, Syrah and Muscat for instance) grow from buds very close to where last year’s growth began. These types of grapes are “spur pruned”; leaving less than an inch of growth remaining from last year.

Leave the canes a bit long and finish pruning when fruit clusters appear to "balance the load".

Other varieties of grapes (Thompson seedless and Concord grapes for instance), their bunches grow from buds several inches further out along last year’s growth. These types of grapes are “cane pruned” because last year’s growth is left longer; 6 to 10 inches in length. This allows the unproductive buds to grow without producing any fruit.

Grape bunches appearing in early May in Las Vegas.

            I delay pruning grapes in our cold desert climate as late as I can. Sometimes even after new growth is well underway. Delaying the pruning this long delays the chance of fruit loss because of freezes and cold drying winds. In the Las Vegas Valley, final pruning may be delayed until late February up until the first week in March. If you want to be doubly sure and a bit lazy about it, delay final pruning until fruit bunches show you where to prune. This might be as late as mid to late April or early May!

You can delay the final pruning of grapes until you actually see fruit clusters (bunches) appearing. Doing this can help balance the load of fruit and make larger berries in the clusters.

            This doesn’t mean you can’t do some pruning earlier. Just be careful and not remove too much of last year’s growth. It’s okay to leave last year’s growth about 12 inches long and cut it shorter than this when you are confident new growth is about to begin or later.