Hoop houses extend farmers season

FLINT, Mich. (AP) - Urban farmers looking to extend the growing season in northern U.S. cities are increasingly turning to plastic-covered greenhouses known as hoop houses.

They're relatively inexpensive and often need no power for warmth in the winter -- relying instead on the sun or heat thrown off by compost heaps. They're being used in cities including Chicago, Milwaukee, Detroit and Flint, Mich.

Hoop houses are typically shaped like half-cylinders with frames made of metal, flexible PVC pipe or wood and plastic sides that can be raised or lowered to control the temperature.

Adam Montri of Michigan State University says hoop houses allow urban farmers to grow a lot of food in small spaces, and they extend a growing season from five or six months outdoors to the whole year.