We currently have two vineyard locations: the 50-acre Oliva Vineyard, with ten acres under vine, is the source for our current wines. The other vineyard location, at Summit Creek Ranch, is home to our test vineyards. Our Summit Creek Ranch test vineyards are each two years old. The Hillside Vineyard is testing the 777 Pinot Noir clone (a real fruit bomb), and the Lucy Vineyard (named after a sweet black lab, now gone), is testing Chardonnay and Sauvignon Blanc. Test vineyards are planted because soil characteristics are a critical factor in determining the potential success of a vineyard. Other considerations are climate and orientation to sun. Although grapevines can be grown in a wide variety of soil types, the most important characteristics are soil depth, good drainage, and water-holding capacity.
Soil depth for vineyards is commonly recommended to be a minimum of 30 to 40 inches before reaching an impermeable layer. Shallow soils limit development of the root system, resulting in smaller vines and greater sensitivity to changes in soil moisture levels. A larger root system can support a bigger vine and is less sensitive to short-term changes in soil moisture.
Drainage is important because grapevine roots require oxygen obtained from air spaces between soil particles in the soil. Poorly drained soils are easily saturated with water, which fills the pore spaces and excludes air. Roots with little or no access to oxygen essentially suffocate and die.
Internal drainage and restrictive hardpan layers sometimes can be improved through soil management practices prior to planting. Drainage tiles can be installed to improve drainage, but this is expensive. Cross-ripping the site to a depth of 4 to 6 feet can disrupt physical barriers such as hardpan or a thin rock layer, which can enable grape roots to penetrate to a greater depth.
The water-holding capacity of a soil is also an important characteristic. Soils with a relatively high water-holding capacity can hold much of the rainfall that reaches it, making it available to the grapevines. Higher water-holding capacity also provides a larger buffer for water consumption by the vines. Soils with low water-holding capacity will require very frequent irrigation to maintain adequate soil moisture levels for grapevines.
Ideally, Summit Creek Ranch soils will reveal deep, well-drained, soils with good water-holding capacity. Although grapevines do not require a fertile soil and are actually easier to manage on soils of relatively low fertility, our soil analysis of both the topsoil and subsoil will be conducted during vineyard site assessment to determine pH and nutrient levels. After that, we’ll know whether the particular clones we’ve planted test well in our area.