Some cities, most notably Vancouver, have websites that match urban landowners who don't care to garden with those who have no space but want to immerse their hands in soil. Here and elsewhere, a few entrepreneurs, engaging in SPIN, or Small Plot Intensive, agriculture, rent backyards — several at a time — to grow produce for sale.

John Taylor is tending Swiss chard, arugula, collards, spinach, turnips and herbs this fall. The crops follow a summer bounty of tomatoes, string beans, peppers, cucumbers, okra, eggplant, sunflowers and other goodies.

Located not in New Jersey farm country or even a suburban backyard, Taylor's farm project is brightening a fenced-in half-acre in downtown Newark. It's a neatly arranged quarter-acre garden that uses some principles of small plot intensive, or "Spin" farming, a concept Canadian farmer Wally Satzewich turned into a company after his experiment in downsizing proved fruitful.

The Philadelphia Water Department and the Institute for Innovations in Local Farming are leading the way at Somerton Tanks Farm, a prototype sub-acre urban farm that takes the conflicts posed by increasing urbanization and turns them to the farmer's advantage. Its pioneering small-plot intensive (SPIN) farming methods provide a viable new economic business model for both experienced and aspiring farmers. And as SPIN farming becomes practiced more widely, it will create new farmland closer to metropolitan areas, which in turn will produce environmental, economic and social benefits.