Yakima County residents live in an American Viticulture Area (AVA) known for growing amazing wine grapes. But with a little work and planning, you can use some of the same principles used by wine grape growers to grow your own table grapes.
There are four genera in the Vitaceae family:
1) Vitis vinifera has its origin in the Mediterranean and exhibits upright growth. Examples are cabernet wine grape and Black Monukka table grapes.
2) Vitis labrusca has its origin in the U.S. and has trailing growth. A good example: concord grapes used for juice.
3) There are hybrid varieties that include many table grapes, for example Himrod.
4) Vitis rotundifolia is from the southeast U.S. One example is muscadine, which can be used for making wine.
What are the basic characteristics of table grapes? The majority are self-pollinating, like full sun and need 150-plus frost-free days. It is best to plant with a southern or southwestern exposure. If planted in rows, they prefer north/south rows and like well-drained, sandy loom soil and rocks, good for retaining heat. To prepare the soil, remove any weeds then add sand and some organic matter.
The next decision is how you are going to incorporate a trellis system.
Trellis systems are best put in before planting so you won’t disturb growing roots. If plants are to be in a row, set treated end posts deep into the ground and secure three to four No. 10-12 high tensile wires. You can also use an existing fence, stone wall or other natural objects; just lean plants at a 45 degree angle toward the object when planting.
If you prefer a free-standing arbor, be aware that it does requires more attention to pruning and training canes onto the support. The fun part is that the canopy acts as a source of shade as well as delicious fruit. A favorite trellis system is to use pergola that is over an existing patio or deck. Here you plant at the base of each post, and the next year train two to three vines up each post, securing with ties and removing all lateral growth, retaining the leaves. It is important to go for length in order to establish the trunk up the post and then cordons on the lateral perimeter wood. When fully established, the cordons on the perimeter wood will produce lateral branches that can be tied to the crosspieces of wood on the pergola for shade. When it reaches the end of the crosspiece, cut the end of the growing cane to contain the lateral growth.
How do you acquire the grape plants? You can propagate your own if you have existing grape plants or if you know a friend with table grapes. This is done by taking cuttings during pruning in the spring. However, to fully develop the root system it is best to keep them in pots or nursery rows for two years before planting at your selected location. The easier option is to buy plants that are already rooted from a local nursery.
Planting grapes is best done in March or April if bare root or May to June if they are greenhouse plants. It is important to place plants 4 to 8 feet apart. Place the plant in the hole, cover with dirt and firm the soil around the plant. Assure an indentation is made around each plant for water to settle; it is best to water deeply every seven to 10 days, depending on the heat. This will allow development of a good root base. Fertilize with weak balanced nitrogen in early spring on new plants, weed around the plant or you can place fabric cloth and rocks around the base of each plant.
For watering, drip irrigation is best (emitters should be placed on each side of the plant) or you can use a soaker hose. It is best to use an in-line filter for irrigation water but is not necessary if house water is used. Avoid an overhead sprinkler system as this encourages diseases such as powdery mildew.
As the grapes grow, there should be minimal care. Just allow them to grow naturally as they develop their root base. In September, the plants should be hardened off by water stressing — the leaves change color and drop off (defoliate). It is then best to give the plants a thorough watering in October. Young plants can have mulch placed around them to overwinter; however, most varieties are very cold tolerant.
Sorry to say, but no grapes will be produced the first year.
In the second part of this article on Nov. 29, we will continue discussing growing grape plants into their second and third year and beyond.