Urban Farming: Essential Answer

May/June 2010

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Urban Farming: Essential Answer

Photo: Tdorante10 / Wikimedia Commons (

Q: I'd like to grow my own food. I live in Scottsdale, Ariz., on a 2.4-acre lot. I'm fascinated by urban farming. 1) What are the most nutritious foods I can grow, appropriate to the climate here in the Phoenix area, maximizing use of space, ease of farming (I am free weekends and evenings, but I'd prefer not to spend the whole time in my garden), and I'd like to have a variety of food year round. 2) Could you design a modular raised "parking lot" garden for the Southwest, where covered parking is coveted and weather accommodates year-round farming?

Asked by Tom Nelson, ’93, Scottsdale, Ariz.

With spring in full bloom, urban farming is a popular topic. And well it should be, as growing your own food is not only healthy for your diet, but also good for the environment. Even better, growing potatoes in the backyard gives helps keep you from becoming a couch potato yourself. Plus, you help society as a whole by adding to the food supply and helping ensure there's plenty to go around. In many parts of the country, small, well-tended plots—as little as 1,000 square feet—can provide most of a household's yearly vegetable needs.

Each area of the country presents its own challenges to the home gardener. Scottsdale, Ariz., has a long growing season, from mid-February through November, and you've got plenty of land, so you're out ahead of many Northerners and downtown-dwellers. But water is going to be a big challenge—throughout the year the precipitation in the Phoenix Area is hardly more than one inch per month. I don't know how you manage the water supply in your garden, but Flood Irrigation in Phoenix, which is managed by Salt River Project (SRP), may be able to help you. Scottsdale is within the SRP flood irrigation boundaries.

You can grow more than 100 kinds of food in the Phoenix area with just a moderate water supply, carefully applied. Since I don't know what your favorite food is, I will only recommend a few very nutritious kinds in the following table. You will find more nutrient data at the United States Department of Agriculture (USDA) website.

  Nutrients Time to plant Time to harvest Water needed
Leaves of lettuce

Vitamin A and folic acid 2-4 weeks before the last frost date or 6 to 8 weeks before the first frost date One of the first crops to yield in the spring, and last to go in the fall Moderate

Carrots laid over soil.
Dietary fiber, antioxidant and Vitamin A A great starter for your garden in the early spring Harvestable 30 to 40 days after sowing Small amount of water needed during the first eight weeks of the growing season, water heavily only if soil dries out as the crop matures

Some florets of broccoli.
High nutritional density but low fat; multiple nutrients with potent anti-cancer properties Plant in late summer, fall, or winter for crops in winter or early spring. In cold-winter areas, set out young plants two to four weeks before last frost Most varieties are ready to harvest 50 to 100 days after setting out plants; over-wintering types may take six months Moderate

Heads of cauliflower
      More water than broccoli
Citrus (orange)
Arizona Sweets

Sliced and whole oranges.
Vitamin C The best time of year to plant a citrus tree is in late September Early winter to early spring See citrus watering schedule

Sliced and whole cantaloupes.
Vitamin C, Vitamin A and dietary fiber At least four weeks after the last frost date Takes 80 to 100 days One inch of water a week for most of the growing season
All pictures courtesy USDA

No matter where you live, climate, water and soil are the most important factors you need to consider when deciding what to plant. Sunset magazine's climate zone map can help you find your climate zone and the perfect plants for your yard according to the sunlight and water condition in your garden.

And if you really want a lot of food, with a minimum of maintenance work? You might want to consider the biointensive method, described in John Jeavon's How to Grow More Vegetables. It is an intensive planting method designed to make your land more productive, and to maximize yields by using the soil and space more efficiently. More details about biointensive gardening can be found in the Nitty-Gritty.

Your second question is a difficult one. I can imagine that people living in desert areas desire to see the green. But there's a problem. "Green roofs only do well in warm and humid places," Professor Jeffrey Koseff, Co-Director of Stanford's Woods Institute for the Environment at Stanford, recently explained to your SAGE authors. We were on a tour of the Jerry Yang and Akiko Yamazaki Environment and Energy Building (Y2E2), the most environmentally sustainable building on Stanford campus—where there is no green roof for exactly that reason. If Palo Alto is too hot and dry for rooftop vegetation, it's hard to think of a covered parking lot in Scottsdale that wouldn't be. I did find an article on the American Institute of Architects' website about some people who managed to have a green roof in Tucson, but it is only possible with a professionally designed roof landscape and irrigation system.

What's required, I think, is a little creativity. I think vine-covered parking may be a good alternative. Imagine having a parking lot covered not with carrot-topped concrete, but with a green sheath of trellised vines—grapes, melons, squash and pumpkins, even kiwi fruit all grow on vines, and can give your car all the nice, cool shade it needs—along with grapes and other produce. Yes, you can grow grapes in Arizona; just don't be surprised if you get a little juice on your paint job.

Jingshi Wuis a PhD candidate in geology.

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