Growing grapes in southeast Idaho

When growing grapes in southeast Idaho, it is important to remember you are growing grapes in southeast Idaho.

We just don’t have the growing season for much variety. Don’t expect to grow grocery store grapes in your backyard. However, we can get good production on varieties that provide delicious grape juice and jelly and passable table grapes most years. Of course, this isn’t true in areas that are colder and don’t have an adequate growing season.

For variety selection, refer to, “Grape Varieties for the Inland Northwest & Intermountain West” from the University of Idaho or, “Grape Varieties for Utah” published by Utah State University. In general, you must select a variety that is hardy to about -20 degrees with either an early-ripening cultivar or one that requires fewer heat units.

Concord is the standby for juicing, but it can stretch our growing season in many areas. Reliance is a red table grape variety that does well.

There are restrictions on ordering grape starts from other states to protect Idaho’s grape industry from diseases and pests. You must get new plants from local nurseries or propagate your own cuttings (see Propagation of Grape Vine Cuttings from New Mexico State University). Access to many cultivars is limited in Idaho.

Pruning and training

Now, let’s talk pruning and training. Properly trained vines will result in a more productive harvest. There are numerous systems for training and pruning grapes. The cane pruning system is the best for varieties that perform in our area. Refer to “Growing Table Grapes” from Oregon State University for details on the cane pruning system for grapes.

Grapes must grow on a trellis to be productive. They must have support to keep the wild vine growth off the ground. A chain-link fence is not the best support structure. While it does provide support, it does not lend itself to maintaining vines long-term. If you are planting a new vine and do not have a trellis, put in a stake or post to start establishing the trunk. For training and trellising techniques, refer to “Growing Table Grapes.”

During the growing season, the buds on the fruiting canes will send out shoots with leaves and fruit. Because only the one-year-old wood produces fruit, you know exactly where the fruit will be produced. Fruiting canes only produce for one year. Therefore, during the dormant season, you will remove this cane and allow one that grew from the renewal spur to take its place.

Once you establish the system, grapes are the easiest fruit to prune. They are pruned very heavily — you’ll be removing 80-90 percent of prior year growth every year once your vines are established.

Grapes can be susceptible to iron deficiency in high-pH soils, which is common in southeast Idaho. An EDDHA iron chelate like Miller’s Ferriplus or Sequestrene 138 is a good solution. EDDHA is an acronym for a chelating agent that makes iron available in soils above pH 7.5. Grapes are also sensitive to broadleaf herbicides like 2,4-D. In short, do not use broadleaf herbicides anywhere near where grapes are growing.