Jethro Tull–the agriculturalist not the rock flutist

According to a 2010 report by Ceres “Water Risk in the Municipal Bond Market,” Los Angeles ranks number one in water supply risk. But we’re not alone. Many other US cities including Atlanta, Phoenix and Dallas also face a future of water insecurity.

Due to these water risks we’d all do well to consider ways to grow edibles without supplemental irrigation. This may sound absurd at first, but I’ll note that in our garden we’ve discovered, quite by accident, that many plants such as prickly pear cactus, cherry tomatoes, cardoon and pomegranates will do just fine in a climate where it doesn’t rain for six months out of the year.  Scott Kleinrock at the Huntington Ranch proved that you can grow chard in Southern California with almost no irrigation through a hot summer (the chard thrived in the Ranch’s food forest under almost complete shade).

As an avid gardener in a dry climate I certainly use a lot of water for my vegetables. Most modern vegetables are adapted to copious watering. But this was not always the case. A classic book Dry Farming by John Andreas Widtsoe, first published in 1911 and available as a free download in Google Books, describes how many farmers got along without the modern conveniences of supplemental irrigation.

A dry farmed wheat and alfalfa field in Wyoming from Dry Farming

Other than the advice to till frequently (tilling, among other things, destroys beneficial fungal networks), Dry Farming has some good tips:

• Maintain soil fertility 
• Plant deeply
• Plant varieties adapted to dry farming
• Know when to plant
• Pay attention to soil structure

The main takeaway for us home gardeners will be the development of drought tolerant veggies. Native Seed Search is a good start, but seed saving will be the ultimate solution. We’re simply going to have to breed drought tolerance back into our water hungry vegetables. Combined with passive water collection techniques such as sunken rather than raised beds, those of us in arid climates can grow a surprising amount of food with a lot less water.

Clarification: dry farming is not growing during the rainy season (which is called “rainfed agriculture”). Dry farming uses strategies to store water in the soil during the rainy season and then grow during the dry part of the year. Though controversial, dry farming traditionally involves tilling.  It also requires much greater spacing of plants. For more information see the website of the California Agricultural Water Stewardship Initiative.