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Growing grapes in the Northwest

Apr 1st, 2015 | Category: Features, Growing

by David Pike

Imagine grapes on the vine and you might conjure a pastoral scene in France or perhaps the sun drenched fields of California, but few would imagine grapes thriving in their own backyard. Unlikely though it may seem, there are many varieties of grapes which grow very well even in our cool maritime climate. Both table grapes (for eating) and wine grapes can be successfully ripened with a few tips and tricks to help them along.

About 10 years ago a friend gifted me a handful of unrooted pieces of vine he had pruned from his trellis. I stuck the pieces into a pot of soil and kept them watered through the summer. The vines rooted and the following spring we planted them against the south side of an old shed. Today these grapes have completely engulfed the shed under a mountain of unpruned vines. In good years the vines yield hundreds of pounds of small, sweet, white, seedless table grapes. Growing grapes can be this easy, but there is also much more to learn to produce an abundance of higher quality fruit, or to ripen more challenging varieties including wine grapes.

Tom Thornton of Cloud Mountain Farm Center demonstrates grape pruning and trellising techniques during a recent workshop. CMFC trials over 70 varieties of grapes to see which are best suited to our climate. PHOTO BY DAVID PIKE

Tom Thornton of Cloud Mountain Farm Center demonstrates grape pruning and trellising techniques during a recent workshop. CMFC trials over 70 varieties of grapes to see which are best suited to our climate. PHOTO BY DAVID PIKE

To gain more viticulture knowledge, I recently attended a workshop on grape growing at Cloud Mountain Farm Center in Everson, where they are currently trialing over 70 varieties of grapes to see which are best suited to our climate. The class was taught by Tom Thornton, co-founder of the center.

Do some research on varieties to choose grapes which will best suit your desires and your site, and if you plan to grow wine grapes, be realistic about your site’s heat potential to avoid planting a variety which will never ripen. White grapes ripen sooner than reds, and grafted grapes can ripen sooner than non-grafted.

Although the south side of a building is a good warm place to plant grapes, I should add a word of caution about the vigor of grape vines, some of which can grow up to 250 feet of canes per year and attain trunk sizes reminiscent of trees. The oldest grape vine in the world is over 400 years old! The best place to plant grapes is on a sturdy trellis, with a bottom wire at 28 inches in height, and subsequent wires every 14 inches to a height of 6 feet. Orient the trellis North to South to attain an even distribution of precious sunlight. Although it is tempting to allow young grapes to set and mature fruit, much like fruit trees, it is better to remove the fruit during the first two seasons so the energy is put into root growth and the main stem will grow bigger sooner.

Grapes require sunlight and heat to fully ripen, this is the most important consideration in grape growing in our relatively cool climate. To maximize the sunlight and heat we do get, Tom offered some useful tips: Because our soil in this area is often heavy clay and is slow to warm, grapes do best planted in raised beds or mounded soil. Not only does this help the soil warm faster, but it also improves drainage, which is another key factor affecting grape performance. He also advises against using mulches or cover crops beneath grape vines, as this can cool the soil. Keep the soil open and free of grass and weeds which will outcompete young grape plants. Dark colored rocks or dark gravel on the surface can also help warm the soil.

The pruning needs are different for table grapes than for wine grapes, and are also slightly different for every grape variety. Due to space limitations, we won’t get into pruning here. When the time comes, more information on grape pruning can be found online at www.cloudmountainfarmcenter.org/pdf-guides/SuccessfulGrapeGrowinginCoolerClimates.pdf.

The ideal pH of the soil should be 6.8 – 7. Dolomite lime can be used to raise the pH of our usually acidic soils. Nitrogen fertilizers should be use sparingly, if at all, as the vigor of grapes is naturally quite robust. Organic fertilizers containing phosphorous and magnesium can be beneficial, as can carefully measured applications of trace minerals such as zinc and boron, which can enhance the fruiting potential of grapes, but care must be taken not to over apply, or damage may result.

CMFC’s catalog includes this Lynden Blue Dessert Grape variety, developed in Mission, B.C. over 30 years ago. Lynden Blue ripens in early October and is a very productive grape for cool summer climates. COURTESY PHOTO

CMFC’s catalog includes this Lynden Blue Dessert Grape variety, developed in Mission, B.C. over 30 years ago. Lynden Blue ripens in early October and is a very productive grape for cool summer climates. COURTESY PHOTO

Although grapes are draught resistant, they will need some water in dry summers, especially during their first season. There are a couple of concerns to be aware of at harvest time: Grapes ripen all at the same time, and should be picked when they are ripe, not left on the vines because the threat of botrytis mold is high during this time, especially if it rains. Also beware of birds, as they love grapes, so use netting.

This spring I’ve planted another 10 plants of a delicious pink colored variety (unknown). I’ve also started rooting some cuttings from a neighbor of a variety called Lynden Blue, a concord type (dark purple grape). Many varieties of both table and wine grapes suited to our climate (including Lynden Blue) can be found at Cloud Mountain Farm Center. Many thanks to Tom Thornton for sharing his knowledge and inspiring us to take up the tradition here in the Northwest.

Published in the April 2015 issue of Grow Northwest

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