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Grape Research


Research Projects
Organic Wine Grape Vineyard
Wine Grape Cultivar Trials
Variety/Rootstock Trials
Table Grapes
Heat Units

Wine grape research at WSU Mount Vernon NWREC was concluded in 2011, and the Mount Vernon grape research program ended at that time. All questions related to current issues in wine grape growing should now go to Michelle Moyer, the WSU State-Wide Viticulture Extension Specialist (509-786-9234


Although the wine grape research program at WSU Mount Vernon NWREC is no longer active, this page remains a source of information for grape growers in western Washington. It includes data and reports, variety descriptions, and links to other research programs and publications.

Extension Publications

Image of Bulletin EB2001, Growing Wine Grapes in Western Washington

Growing Wine Grapes in Maritime Western Washington (EM068E, replaces EB2001)

Includes site selection, varieties, culture. Can also order online.

Pest Management Guide for Grapes in Washington (EB0762). (updated annually).


Final Report: Wine Grape Cultivar Trials 2000–2008

Pruning grapes in the home garden

Organic Vineyard Establishment: Trellis and Planting Stock Considerations (June 2010)

Grape research at Mount Vernon was initiated by Dr. Bob Norton in the mid 1970s. Trials conducted from 1976 to 1988 identified a number of white wine grape varieties which proved successful in area vineyards. In response to requests from area wine grape growers, Gary Moulton began a new series of trials in 1998 to identify successful red wine grape varieties, and to investigate improved cultural methods such as use of grafted rootstocks. From 2000 to 2008, projects included evaluation of new wine grape varieties, particularly red wine varieties, and rootstock trials evaluating potential for earlier maturity in grafted grape varieties. Observational trials of certain cultural methods for influencing earlier ripening and vigor control were also conducted. In 2008 Dr. Carol Miles initiated a new research project to investigate organic wine grape production, and an organic grape vineyard was established. Lack of long-term support caused the wine grape research to be concluded in December 2011.

Research projects were focused on the potential for high quality wine grape production, though some table grapes have also been evaluated. The Puget Sound region is a marine climate similar to the fine wine producing areas of France and Germany. Annual heat units in different areas range from approximately 1400 to 2400 Growing Degree Days (GDD). The station, located near the ocean in the Skagit River flood plain, is at the cool end of the scale at 1500 average annual heat units.

Annual Reports (2002-2011)

Final Report: Wine Grape Cultivar Trials 2000–2008

Research Projects

Organic Wine Grape Vineyard – 2008 to 2011

This trial was begun in 2008 to follow up on requests from growers for information on organic vineyard management. An advisory group of local wine grape growers identified weed control as a primary limiting factor in successfully establishing young plants in a new organic vineyard. Concluded in 2011, the trial evaluated certain weed management methods suitable for organic culture in a young vineyard, and developed a basic outline for establishing an organic vineyard.

Organic Vineyard Establishment: Trellis and Planting Stock Considerations (June 2010)

Organic Vineyard Establishment: Trellis and Planting Stock Considerations. Sustaining the Pacific Northwest. WSU Extension newsletter (2010)

Tilth Newsletter report

Organic Viticulture Resources – a new guide to information on growing wine grapes organically

Wine Grape Cultivar Trials – 2000 to 2009

Variety trials evaluated red and white wine grape cultivars not previously grown here, from cool climate areas in other parts of the country and world. Grapes from western and eastern Europe, and selections from breeding programs in New York and British Columbia, Canada were included. Replicated plots produced sufficient fruit for wine making and evaluation. A pretrial screening of three plants per entry examined some varieties that were lesser known and possibly marginal in our climate. Varieties that performed well in the screening trial were multiplied and added to the main trial.

Final Report: Wine Grape Cultivar Trials 2000–2008

Varieties included in trial & pre-tests in 2009

‘Pinot Noir’ Rootstock Trials – 2000 to 2008

Selection of rootstocks that promote earlier maturing can expand the areas in which high quality grapes can be produced. A trial was initiated in 2000, consisting of 3 replicated 5-plant plots of Pinot Noir clone 2A, grown on 7 different rootstocks, with self-rooted plants included for comparison. One trial was located at the Mount Vernon research station in the Skagit Valley flood plain, and the second at a vineyard site in the Nooksack River valley near Everson, where heat levels were considerably higher. Rootstocks were evaluated for vigor, productivity, yield and quality of fruit. Data collected included juice analysis (°Brix, pH, titratable acid), yield, and observations of vigor and fruit set.

Abstract: Effect of selected rootstocks on the performance of wine grape cultivar ‘Pinot Noir’ clone 2A

Variety and Rootstock Trials – 2004 to 2009

After seeing results of the rootstock trials in 2002 and 2003, a new trial was initiated in 2004, an advanced cultivar trial grafted to one of two rootstocks: Couderc 3309 or Millardet et de Grasset 101–14. This trial included standard varieties along with promising ones from the pretest and main trial, with the aim of seeing whether the rootstock effects observed in Pinot Noir 2A would carry over to other varieties. Differences between maturity in self rooted and grafted vines varied depending on the variety. In some, such as Madeleine Angevine and Siegerrebe, little difference was seen in the performance of grafted vs. self rooted vines. In other varieties, e.g. Burmunk and Agria, grafted vines ripened and were harvested earlier, and levels of titratable acid were lower compared to self rooted plants in both 2007 and 2008. This trial concluded in 2009.

Table Grapes

Since temperature is the main limiting factor in producing good quality sweet flavor in a cool climate area like ours, only certain early maturing varieties of table grape can be grown successfully here. For example, the most common blue grape, ‘Concord’, does not mature well in most areas of western Washington. In general, grapes require full sun and soils with good drainage and moderate fertility. Placing vines with a southern to western exposure, protecting them from wind, and using black mulching material or river rock under the vines to reflect heat are all methods that may help to enhance ripening. Vigorous varieties like ‘Interlaken Seedless’ can be very productive when trained up over an arbor, assuring that all shoots have good sun exposure.

Some guidelines for pruning grapes in the home garden.

Buffalo – midseason Concord type, blueCanadice – early pinkish redInterlaken Seedless – early white, vigorousJupiter – early, blue, large berriesLynden Blue – very early blue, seeded

Mars – medium early, blue

Neptune – medium early, white

Reliance – early, red, table and juice

Saturn – medium early, redVan Buren – blue Concord type, earlyVanessa – early redVenus – early redNY 78.836.06 – selection from Geneva, NY breeding program


Over the years, support for the trials has been provided at various times by the Washington Wine Advisory Board, American Vineyard Foundation, and the Northwest Center for Small Fruit Research-USDA. The organic vineyard trial was supported by the WSU Center for Sustaining Agriculture and Natural Resources (CSANR), the Washington State Commission on Pesticide Registration (WSCPR), and the Washington Wine Advisory Board.

Cooperation in wine making and production, as well as assistance in harvest data collection, has involved area growers and winemakers, including home growers. The Puget Sound Wine Grape Growers have been active in assisting the organization of our research program, and helping to seek out possible resources. They succeeded in attaining a separate Puget Sound appellation to recognize the unique qualities and characteristics of wine produced in this area.


WSU Viticulture & Enology

WSU Viticulture and Enology Main Page

Organic Viticulture Resources – a new guide to information on growing wine grapes organically

Enology Extension at WSU

Washington State University Wine & Grape Program

Vineyard leaf index rating of herbicide exposure

Grapevine Leafroll Disease (2008)

Contact the grape virologist at WSU for advice on testing grapevine samples for virus and virus-like diseases.

Trellis Tension Monitoring

WSU Extension: Stages of Grape Berry Development

Other Northwest Region Resources

Clean Plant Center Northwest

Preventing Herbicide Drift and Injury to Grapes (Oregon EM 8860, Revised 2014)

Puget Sound Wine Growers’ Association

Wine Islands Growers’ Association – Vancouver Island, B.C., Canada

Northwest Berry & Grape Information Net, comprehensive information and communications resources for the Pacific Northwest berry and grape industry.

Wines Northwest

Other Regions

Production Guide for Organic Grapes (Cornell University Extension, 2014)

Wine and Juice Grape Varieties for Cool Climates, Cornell University Extension

Table Grape Varieties for Cool Climates, Cornell University Extension

Cool Climate Oenology and Viticulture Institute, Ontario, Canada

The Tender Fruit Grape Vine, Ontario Ministry of Agriculture, Food and Rural Affairs, a newsletter for commercial fruit growers.

Viticulture & Enology – U.C. Davis

Pennsylvania Wine Grape Network – Penn State

Wine Grape Glossary

Wines and Vines, an online newsletter