The soil survey in the uplands of southern Monterey County anticipated
the use of these soils for rangeland. It may not be a suitable basis
for planning a specific vineyard. An on-site soil investigation is
necessary to determine the suitability of a specific site for vineyard
development.
Nevertheless, vineyards have been developed on strongly sloping to
steep, shallow and moderately deep soils in northwestern San Luis Obispo
County immediately to the south of Monterey County. Vineyards have been
developed on the Nacimiento, Ayar, Los Osos, Balcom, Linne and Calodo
series. The moderately deep San Andreas series is similar to the Linne
series but has lower organic matter content, lower lime content and
lower water holding capacity. The shallow Gaviota series is similar to
the Calodo series but has lower organic matter content, and lower lime
content
Map unit GdE, ScE, and ScG have the following qualities that affect
their use as vineyards. The mean annual precipitation on these map
units ranges from 15 to 35 inches. Precipitation is higher to the
west. The frost-free season is appropriate for vineyards with 200 to
270 frost-free days. These are well-drained and moderately coarse
textured soils and pose a minimum hazard of root diseases. Phylloxera
does occur in San Luis Obispo County and resistant rootstocks are
appropriate. The San Andreas and Gaviota soils will require irrigation
during the growing season to compensate for limited water-holding
capacity. These are highly erodible soils. A good surface drainage
system and other erosion control practices are necessary on these
moderately steep to very steep slopes.
The following varieties are grown in the Paso Robles Area: Zinfandel,
Cabernet Sauvignon, Merlot, Chardonnay, Sauvignon Blanc and 35 other
varieties.
For more information you may contact:
University of California Coop Extension
Mary Bianchi (805) 781-5940
Horticulture Farm Advisor
2156 Sierra Way, Suite C
San Luis Obispo, CA 95401
Paso Robles Vintners & Growers Association
1940 Spring Street
Paso Robles, CA 93446
(805) 239-8463
E-mail: prvga@pasowine.com
Website: http://www.pasowine.com
