Established 1983

Washington State’s first federally-recognized appellation, Yakima Valley, spans 11,000 vineyard acres – over one-third of Washington’s vineyard plantings. A cooler climate appellation due to its proximity to the Cascade Mountains, the Yakima Valley is well-suited to producing fully mature white grape varieties while retaining good acidity and fresh fruit flavors.


Mercer Estates Sunnyside Vineyard

Sunnyside Vineyard

Significance of name: Sunnyside is the name of the nearby city – the vineyard was previously owned by multiple owners and was called RVP – a.k.a. – Rosa Vineyard Partnership.

Size: 140 acres, 22 blocks
Aspect: North and South row orientation
Location: Sunnyside – approximately 15 miles W of Prosser
Soil: Sandy loam
Varieties Planted: SE 3%, SB 9%, CH 31%, WR 27%, PG 25%, GT 5%
Year Planted/Expanded: 1983-84
Microclimate: Cooler – Long Term Average GDD = 2610
Appellation: Yakima Valley
Unique Aspects: Higher elevation 1200′, cooler, sloped blocks, lower vine density – source of estate Mercer PG and CH.
Average Yield: All varieties 5-6.0T/A.
Trellising: Vertical Shoot Positioned with 2 fixed canopy wires.

Farming Practices: All vine rows are oriented generally from north to south, drip irrigated, spur pruned and cordon trained to a “Vertically Shoot Positioned” trellis with 2 fixed canopy wires. Vines are trained to a modified sprawl system. All blocks are planted 10 feet between rows and 7 feet between vines for a vine density of 622 vines per acre. The vines are managed for fruit production in year 3. This allows for optimum vine health, improved vine to vine uniformity, enhances consistent yields earlier and reduces the risk for poor stand and long term retraining efforts.

Vineyard management of all blocks is organized and timely. Current integrated pest management and sustainability practices are priorities. Vines are cordon suckered at about 3-6 inches of growth. Cordon suckering is the early removal of unnecessary non-count shoots. Selective leaf removal on the east side of canopy is standard protocol and if needed, a second leaf removal pass to fine tune canopies can be accomplished. Crop estimations are made in late July when berries are pea size or larger. Cluster thinning recommendations are made and target yield adjustments are accomplished by veraison for all varieties. Follow up estimates are made on blocks that appear over cropped and a second thinning pass can be made if necessary.

Once berries soften (veraison) a green color thinning pass (removal of secondary fruit or late maturing fruit) is accomplished on most varieties. For example, Pinot gris retains many seconds and green thinning is important for this variety. Vines are closely inspected for insect and disease incidence, monitored and controlled accordingly. All vines are machine harvested unless special requests are made.