Dry Farming – The Future (and Past) of Wine in California

Before the 1970’s, all vineyards planted on earth were “dry farmed.” Simply, winegrowers had to rely on precipitation as the only source of water for their grape vines. Today in California, you’d be considered crazy to plant a vineyard without an irrigation system. In fact, you might not be allowed to.

What? There’s no law against dry farming, you say. Technically there isn’t. But a bank today is highly unlikely to lend to a winery that wants to plant a vineyard without irrigation.

The commercial demands of viticulture in California are part of the reason irrigation became the norm. Vineyard growers discovered that you could grow more grapes per acre if you irrigated. Once this link was established, banks wouldn’t lend to a commercial grape growing operation without this promise of greater yields, and therefore more predictable profits.

As climate change progresses, the resulting increase in the extremity and frequency of drought in the Western United States has begun to make it clear that reliance on irrigation is what’s crazy. Water use restrictions will likely eventually make it very costly to irrigate, and at some point there may just not be enough water. At some point we may face a choice of having water or wine to drink, but not both. And as much as I would be the first to joke that I’d choose wine, the reality of a water shortage for a city like Los Angeles, for example, would be catastrophic.

And irrigation isn’t necessary for the most part. Places like the island of Santorini, Greece have been dry farming vines for millennia on an average rainfall that is less than that of Los Angeles. Los Angeles was the first great wine region of America. The main center of winegrowing in the1800’s wasn’t Northern California, but Southern, all grown without irrigation. Yet now we irrigate vineyards in Northern California where they get twice as much rainfall as Los Angeles.

Comparing rainfall in California with other areas around the world that dry farm shows that dry farming is possible in California.

Santa Barbara County gets an average of over 19 inches of rain per year.

There are a few caveats – maybe it’s better to call them requirements – for dry farming. You can’t just stick any old vine in any plot of land and expect to successfully dry farm a vineyard.

First, you need the right rootstock. Much of the rootstock on which wine grapevines are growing, due to their resistance to phylloxera, are riparian or riparian crosses. That is, they evolved in moist, river bottom soils where phylloxera also evolved. That’s why riparian rootstock can resist the pest.

But to save the vines from phylloxera, we’ve put them on rootstock that does not do well in the dry Mediterranean climates, like California, where we grow most of the wine grapes. Planting on riparian rootstock in the US West at this point in history is not only silly, it’s irresponsible. There are great alternatives to riparian rootstock, bred both for pest resistance and drought tolerance. Here’s a full list of common rootstocks, with their qualities, provided by UC Davis.

In addition to the right rootstock, you need the right land planted in the right way. The soil must be of sufficient depth and water-holding capacity, the vines must be planted far enough apart so that they don’t compete with each other for the water in the soil, and you need to manage the vineyard ground between vines to minimize evaporative loss and maximize water retention. In a place like Oregon, with generally abundant winter precipitation, this doesn’t necessarily mean your vineyard will look any differently than an irrigated vineyard. But in drier areas this will mean fewer appropriate vineyard sites, and fewer vines per acre – resulting in decreased productivity.

The main way to manage evaporation and water retention is to stop tilling and grow cover crops. Cover crops can compete somewhat for water when establishing a new vineyard with young vines. But once a vineyard is established and the vines are 3 to 7 years old, depending on their vigor and the site, there generally is no more competition. The cover crops actually help water retention, by reducing the soil temperature and increasing holding capacity, and they allow better water penetration down to the vine roots… not to mention the myriad other benefits such as erosion prevention, habitat for beneficial insect, biodiversity, healthy soil microbiology, and fungal networking.

The results of un-tilled, dry-farmed vines planted appropriately and on rootstock matched to the location, can be stronger vines with longer lives, better health, and better resistance to drought. This is one of the reasons why vineyards planted in California in the 1800’s can still be found producing grapes today. These factors of health and longevity can offset the costs of dry farming in the long run.

Sustainability arguments aside, there’s another really great reason to dry farm: it results in delicious, terrior-driven wines.

Irrigation in viticulture is literally watering down our wines. When we don’t water the vines, their roots dig deeper, strengthening the vine’s connection to the soil. They become better able to self-regulate, especially in times of stress. And they produce fewer grapes, in dry times or in dry climates, with brighter, more concentrated flavors.

If terrior means anything in wine, the natural water supply for the vines from precipitation, natural ground water, and fog must be part of it. We can’t simultaneously believe in terrior-driven wines and irrigate our vineyards. You are eliminating one of the key elements of terrior the minute you irrigate.

This is why in much of Europe – France, Italy, Spain, Germany – vines cannot be irrigated after reaching producing age (usually at least 3 years), if you want the resulting wine to be classified as originating from a designated viticulture area.

One of the key differences, philosophically, between old world wines and US wines is that while banks have made it nearly impossible to dry-farm wine in the US, the old world has made it against the law to irrigate their best wines.

As wine in the USA matures, it seems likely that someday in the not too distant future we’ll see an AVA self-designate as “dry-farm only.” The Deep Roots Coalition (DRC) has promoted dry farming in Oregon for years.  With at least 27 wineries who are members of the DRC, and significantly more annual rainfall than California, it seems likely Oregon will be the first to begin regulating and enforcing dry-farming.

But California has a few dry farmed vineyards as well. Some of the oldest vineyards, which were of course planted without irrigation, have continued to be dry-farmed. And there are several lists of dry-farmed California wines online.

In 2021, Centralas made wine from dry-farmed organic zinfandel vines in Southern California that received only 5 inches of winter rain. The vines were planted around 1918 and were likely flood-irrigated for the first few years, but they have not been sprayed or watered for generations. The wine will be released in the fall of 2022, and in barrel it tastes incredible.

The commercial fears of dry farming in a place like California are understandable. But the rewards of dry farming wine are delicious, sustainable, and soon may be imperative.

The California Ag Water Stewardship Initiative has some great resources about dry farming if you'd like to learn more.