A Study of Wine Grape Varieties Planted in San Luis Obispo County

Grape growing. Viticulture. Vineyards. A complex ecosphere. How did San Luis Obispo County become an important part of the now thriving industry of wine grape growing and winemaking?

Current Survey Methods for Grapes’ Tabulation

The United States Department of Agriculture has a National Agricultural Statistics Service (NASS) in each state. The Pacific Regional office partners with the California Department of Food and Agriculture, the California Table Grape Commission, and Raisin Administrative Committee to conduct an annual acreage survey of California grape Growers. The purpose of this survey is to provide annual grape acreage with information on new plantings and removals consisting of two parts: estimated grape acreage and detailed data by variety (as voluntarily reported by grape growers and maintained in a list of grape vineyards). It is a continuation of a long series of industry-funded grape acreage surveys.

However, this data is, at best, less than 100% correct due to three major reasons: 1) a voluntary survey of approximately 8,900 grape growers is unlikely to ever attain 100% completeness; 2) it is difficult to detect growers who are planting grapes for the first time, and 3) the detailed data reflects vine removals from 30,000 acres during the past twelve months for the 2020 data.

Procedures

In October of each year, a questionnaire is mailed to all grape growers, which includes farm operators, owners, and management firms, from the list of grape vineyards in California. Producers are asked to update the information from previously reported crop, variety, and acreage information that is preprinted on their questionnaire. The updated information needs to include new plantings, removals, and any other corrections. New growers are mailed a blank questionnaire. All growers are given six weeks to respond by mail with a follow-up to the growers by telephone.

Results

The tallied results of the questionnaire are available to the public by April of the following year. For example, the questionnaire for 2020 was distributed to grape growers in October 2020, grape growers returned their questionnaire by mid-November 2020, and NASS or National Agricultural Statistics Service produced the results as the California Grape Acreage Report 2020 Crop by mid-April 2021. This occurs every year.

In the state of California, the leading wine-type varieties continue to be Chardonnay for white wine grapes and Cabernet Sauvignon for red wine grapes. This is also true in San Luis Obispo County. 

California’s 2020 wine grape acreage is estimated at 580,000 acres of bearing fruit from the results of the questionnaires. This is in comparison to 590,000 acres in both 2019 and 2018.

San Luis Obispo County by the Numbers

Between 2017 and 2020, the total amount of white wine grape acreage increased by 22 acres.  The total amount of red wine grape acreage for the county decreased during this four-year span. The red wine grape acreage decreased by 31 acres. 

White Grapes

White wine grapes are grown in forty-eight counties in the state of California. The following chart exhibits that twenty-three varieties of white wine grapes are planted in San Luis Obispo County with the type with the largest acreage being Chardonnay. However, between 2017 and 2020 Chardonnay acreage decreased in the county by 356 acres, or about 12%. Additionally, White Riesling acreage changed by 43 acres, which amounts to a decrease in that variety of 57%. The “other white” line in the chart includes different varieties with very small amounts of acreage.

Interestingly, during that same four-year span Sauvignon Blanc increased in acreage by 283 acres by 2020, which amounts to a 35% increase from its acreage in 2017. Other big upward movers were Grenache Blanc, Pinot Gris, and Vermentino. Downward trends in white grape acreage in San Luis Obispo County include Albarino, Muscat Blanc, and Viognier.

SLO County Acreage of White Wine Grapes by Variety

Red Grapes

Red wine grapes are grown in forty-nine counties in California. Thirty-five different varieties  are included in this category for San Luis Obispo County and information concerning them appears in the following chart. The “other red” category includes a conglomeration of different red wine grape varieties in small acreage. 

Six different varieties of red wine grapes grown in San Luis Obispo County are at minimum 1,500 acres, but the top crop of red wine grapes in this county is Cabernet Sauvignon holding fairly steady in total acreage over the four year period. There was an increase of 309 total acres for the county reported, amounting to a 2% increase in that variety. The other top red varieties in this county include: Merlot – decrease of about 10% in acreage, Petit Sirah – increase of 4% in acreage, Pinot Noir – decrease of about 2%, Syrah – decrease of 10%, and Zinfandel – decrease of 10%.

One of the red varieties totally disappeared during the four year period; that being Meunier. In 2017 the county had reported twenty-one acres of that variety were being grown. By 2020, as reported in the survey, Meunier is no longer being planted.

What is interesting to review is that some of the smaller acreage amounts for red wine grape varieties now being planted in San Luis Obispo County is showing more interest including:

• Aglianico – an ancient grape planted almost exclusively in southern Italy, 
• Cabernet Franc – plays an important role in blends, 
• Carignane – originated in northeastern Spain and used in blends, 
• Cinsaut – a southern French grape used in blends, 
• Cournoise – from southern France used in blends, 
• Dolcetto – northern Italy grape to make an everyday wine, 
• Graciano – a Spanish grape used in Rioja blends, 
• Grenache – an inspiring Spanish grape used for wonderful wines and blends, 
• Malbec – southwestern France origin now a leading grape for fine red wine, 
• Mourvedre – Spanish in origin gives a kick to Rhone blends, 
• Petit Verdot – a Bordeaux grape used to blend with cabernet sauvignon or merlot, 
• Primitivo – originally from southern Italy, and 
• Tannat – originally from southwest France, then to Uruguay and used to make a soft wine. 

Some of these varieties appear in historic records of early pioneers from our county. What is old is new again?

Note: Much of this information describing the wine grape varieties is taken from “The Wine Bible” Glossary of Other Grape Varieties Worldwide.

SLO County Acreage of Red Wine Grapes by Variety

In Summary for San Luis Obispo County

Total white wine grape acreage

Total red wine grape acreage

The downward movement between 2019 and 2020 could be from either the Covid-19 pandemic presence or weather-related based on wildfires with the resulting smoke taint present in the state. The decrease between the previous year amounted to a 2% decrease in acreage. Experts say this did not amount to a bad thing, but balanced the market as in the past several years there was an oversupply to the wine grape market. 

How Many Varieties of Grapes Really Exist?

“There are five thousand to ten thousand varieties of grapes, but” according to Karen MacNeil, author of “The Wine Bible” as she explains, “scientists do not have an exact figure because many varieties are thought to exist solely in laboratory collections, and are no longer cultivated. Of this large number, about 150 are planted in commercially significant amounts”. MacNeil goes on to explain “throughout the entire history of winemaking – and indeed right up until the early 1990s – the only way to try to tell the difference was by ampelography.” You will not be surprised that this was not a foolproof method and farmers sometimes got it wrong. However since the early 1990s identification of grapevines is done by obtaining DNA of a grape variety by research and comparing it to the DNA of known varieties.

“History of San Luis Obispo County California with Illustrations and Biographical Sketches of its Prominent Men and Pioneers”

(Known by two names, either the “Myron Angel” book or the “Thompson & West” book)

In 1883, Myron Angel (1827-1911) compiled and was the editor of the history published by Thompson & West about San Luis Obispo County which at the time had a population of approximately 9,000, with the book entitled, History of San Luis Obispo County with Illustration and Biographical Sketches of its Prominent Men Pioneers. The Wine History Project of San Luis Obispo County values this early detailed book of history because Myron Angel actually lived in our county for 28 years. He chronicled the early years of the county between 1850-1883 with infinite detail and it is still a great source of historical information. Later in his life he also contributed to the history of both the Painted Rock located in the Carrizo Plain, San Luis Obispo County and California Polytechnic School. 

Myron Angel edited for two newspapers in the area,  the Weekly Tribune and later the Daily Republic.  In addition to his newspaper work, perhaps Angel’s greatest contribution to the community of San Luis Obispo and to the state of California was his role in the creation of a polytechnic institute in San Luis Obispo. Beginning in 1894 he had an idea for a school that would provide training in agriculture, mechanics, engineering, and business methods by convincing a group of local citizens to lobby for a state school located in San Luis Obispo. According to history found in the CalPoly library collections, “on March 8, 1901, Governor Gage signed legislation to establish the California Polytechnic School. On a visit to San Luis Obispo on May 9, 1903, President Theodore Roosevelt praised the citizens for their support of the state school. The first classes met October 1, 1903.” 

Largely because of Myron Angel’s efforts, the university today is a key factor in the continuing economic, intellectual, and social development of  the community. Because of this he has become known as the Father of the California State Polytechnic College. .

According to the book edited by Myron Angel and published by Thompson & West covering the years of 1850-1883, on pages 224-225, Angel included a listing of the statistics of production of fruit as reported by the Accessor in San Luis Obispo County during the early years of grape growing in the county.

• 1873
  • 60,000 grapevines
• 1876
  • 80,000 grapevines
• 1882
  • 52 acres of grapevines
  • 2,120 gallons of wine
• 1883
  • 85 acres of grapevines

In this same publication, on page 230, are the following facts listed for the years 1882-1883:

• Mr. Frank McCoppin planted a vineyard with 100,000 vines on the western slope of the Santa Lucia Mountain in the Van Ness Canon. (marking above the n in Canon)
• Mr. H. A. Vachell planted a large vineyard of 558 acres on the eastern slope of Mr. Buchon in the coastal range near Arroyo Grande. 
• Dr. W. W. Hays planted a large vineyard in the northern suburbs of San Luis Obispo town.
• Mr. W. T. Sheid on the Estrella, grew celebrity status grapes.
• Mr. Joseph Frederick on the San Miguelito Rancho by the ocean grew “excellent quality” grapes.
• The Steele Brothers, on the Corral de Piedra, also grew grapes and other fruit.

There was an economic boom in the country by the 1880s resulting in the planting of more than 150 vineyards in San Luis Obispo County. The local businessmen bought varietals from local nurserymen and sold the wine from those grapes to friends and dairymen at fairs and in markets. Local papers had articles on grapes, competitions, and growing methods. 

In a newspaper article contributed by P. H. Dallidet, Jr., son of the first commercial winemaker in this county, was an article on local vineyards and grape growers. Dallidet, Jr. stated that there were 150 vineyards in the county during that year and named those citizens from the county who were involved in planting and growing grapes. Names such as J. P. Andrews, the Goldtree brothers, John Pinckney, Captain Marcus Harloe, George W. Hampton, J.H. Hollister, P. Quintana, Henry Ditmas, Charles H. Johnson, and many others, some mentioned below. 

Other San Luis Obispo Historic Wine Grape Information 

According to the California State Board of Agriculture, by 1910 there were 265,281 grapevines in the county and by 1920 that amount had decreased to 148,842 grapevines because of the threat and upcoming laws of prohibition in the United States. However, let’s look back on the years leading up to that time in San Luis Obispo County.

By 1896 in what is now known as Templeton, California, Andrew York had forty acres planted. His winery was known by A. York and Sons by this time; the wine grape that was planted on this acreage – Zinfandel. And by 1902 this family was producing 40,000 gallons of wine per year, with 20,000 of those gallons of wine being shipped to the East Coast of the United States. By 1906 this family added more land and planted more vineyards, now adding Grenache, Carignane, and Alicante Bouchet grapes with the acreage amounting to 80 acres of grapes by 1907. In 1911 over 100,000 gallons of wine was produced from this winery.

Around 1900, A. B. Hasbrouck of the Arroyo Grande valley area had purchased thousands of acres and planted a vineyard of 35 acres of sandy loam soil in which he planted various grapes. These include the following wine grape varietals: Grenache, Zinfandel, Charbono, Riesling, Pinto, and Chesselar Rose. Hasbrouck supposedly also planted table grapes which included Muscat, Rose of Perri, and Black Hamburg. These grapes were dry farmed and the yield of each acre was four to six tons of grapes with each one ton producing 150 gallons of wine which he produced in his St. Remy winery.

In the Geneseo district, the Ernst brothers (John, William and Martin) planted thirty acres of grapes in the late 1880s and 1890s, yielding 3 ½ to 4  ½ tons per acre. Their wine grapes included: Zinfandel, Mataro, Carignane, Burger, Mission, Semillon, Riesling. Their table grapes included: Black Morocco, Malvoise, Rose of Peru, Black Hamburg, Muscat, Flame Tokay, and White Assyrian.

What a Difference 137 Years Makes 

It is interesting that in 1883 according to Myron Angel reporting the Assessor’s report, there were 85 acres of wine grapevines in San Luis Obispo County. And numbers taken from the California Grape Acreage Report 2020, there were 34,685 acres of wine grapevines planted in this county. San Luis Obispo County’s contribution to the state of grape growing has indeed become important.