Check out this article in the SF Chronicle, featuring yours truly as expert in local food-growing techniques for a low-water future!
Here's the link.
Or read my part below:
Using less water
Even if dry farming is not for you, there are ways to save water in your home or community garden. Here are some tips from urban gardener Antonio Roman-Alcala and Flatland Flower Farm's Dan Lehrer.
Always use mulch. Mulch (any organic material placed at the surface of the soil) will prevent evaporation and retain soil moisture. It also regulates soil temperature, suppresses weeds and provides a habitat for beneficial organisms. Straw is good for annual beds and wood chips for perennial crops.
Drip irrigation. If you have to irrigate, use drip lines as much as possible. They are far more water efficient than sprinklers and hoses and deliver water where it's needed - to the roots, rather than the leaves. It also reduces mildew and disease.
Watering schedule. If all you've got is a hose, reduce evaporation by watering in the early morning or evening, not during the heat of the day.
Water catchment. During the rainy season, capture precipitation in barrels, small ponds and other storage containers. Although the legality is in question if not up to code, home gray-water systems are also a way to recycle large amounts of water from sinks and showers.
Plant thickly. Reducing open space in beds will cut down on evaporation.
Row cover. The translucent fabric can be draped over crop rows to protect against pests and help retain moisture and heat.
What to plant
Flatland Flower Farm's Joanne Krueger recommends these non-edible plants that look good and don't ask for much in return.
Succulents, Kangaroo Paws, asters, lavender, blue-eyed grass, bay trees, rosemary, artemisia, perennial sunflowers, gladioli and a variety of bulbs, especially daffodils.
Tips, techniques and how-tos
Several parameters should be considered to grow food crops successfully without irrigation, says Dan Lehrer.
For one, it won't work with greens and other water-dependent plants, which will quickly wither in dry months. Dry farming is also geographically specific, generally exclusive to temperate coastal climates with periods of consistent rainfall, as well as some fog exposure.
In addition, it's necessary to have a decent amount of space and deep, rich clay soil without any obstruction. It won't work in pots, since the roots should reach down far, upwards of 10 feet in the case of tomatoes. This factor is an automatic deal breaker for people gardening in raised beds or in yards on top of concrete foundations. Also excluded are most residents of San Francisco's Sunset and Richmond districts, who live on sandy ground that won't hold enough moisture during dry months.
But it can be done in areas of the city where food has traditionally been grown, including the Mission District, Bayview-Hunters Point and Noe Valley, said Lehrer. And, he adds, it's perfect for the rich clay alluvial plains of the East Bay that stretch from the flatlands in Richmond to the red earth of San Jose.
The chances of success for the plants will also increase if the soil is amended with compost before transplanting, and a generous helping of mulch laid down afterward to hold in the moisture.
"In the Bay Area, in a normal year of rainfall - though clearly normal may no longer exist - one can grow lots of crops over the rainy season with little or no additional irrigation," says Antonio Roman-Alcala, an urban gardener who works at Alemany Farm, a community project on a 4 1/2-acre plot off I-280 in the south end of San Francisco.
For the past two summers, the farm has grown dry-farmed tomatoes and this summer will likely try to dry-farm pumpkins as well. Outside of summer, Roman-Alcala notes, garlic, onions, cole crops like kale and collards, fava beans, peas and others can grow with minimal irrigation from October to June. "If there is enough rainfall, you just plant, maintain and collect your produce. No watering necessary."
Most experts agree that the best dry-farmed returns come from tomatoes, especially the Early Girl variety, a popular and hearty hybrid with deep roots.
"They're a really tough plant," said Lehrer. He notes that in the middle of the summer, after months without water, the plants might not look great. "You'll start to worry about them, but don't worry about it. They're putting all their energy into the fruit."
Jim Leap, the farm manager at the UC Santa Cruz Center for Agroecology and Sustainable Food Systems, began dry- farming Early Girls 19 years ago, a technique he learned at Molino Creek Farm in Davenport (Santa Cruz County). He's been teaching his students how to do it ever since, and has more recently experimented with beds of winter squash, dry beans and grain corn, as well as apple and apricot trees. He also knows of a Marin farmer successfully dry-farming potatoes.
"People just like to water plants, and plants just don't need that much water," he said, noting dry farming also cuts down significantly on weeds.
When Leap first started selling his dry-farmed Early Girls at local farmers' markets, they sold like hotcakes as customers became quickly enamored by their uniquely sweet, rich flavor. He describes a trial test he once did with irrigated and dry versions of his Early Girls, finding the former, in comparison, completely devoid of flavor. During one year, he said he made $10,000 selling dry-farmed yields from a third of an acre alone. But in recent years, he's lost that market niche as more small farmers are growing them, some his former students. "Our sales are way off because there's so much more on the market," he notes. "You can blame us because we taught everyone else how to do it."
Leap said the challenge is to get the timing just right and trap the moisture by tilling the soil after the rainy season. In years of standard rainfall, he then transplants his tomato starts in late May. The plants will send roots into the moisture layer, typically as much as 10 feet down into the deep clay in search of residual rainfall.
Full sun exposure and generous spacing is required to accommodate the plant's extensive root system, he adds, which may be a limiting factor for home gardeners. He's calculated that each season, his crop conserves about 325,000 gallons of water per acre-foot compared to their irrigated counterparts.
"I'm this one lone voice in the woods, saying, 'You don't need to water, let it go,' " said Leap, noting that many growers make the common mistake of watering heavily after transplanting, causing the plant to establish a shallow root zone and immediately wilt without steady irrigation. "If you over water, you're just leeching nutrients into the groundwater and wasting precious resources during drought times."