This story appears in the March 2011 issue of National Geographic magazine. Row upon row, tomato plants stand in formation inside a greenhouse in Willcox, Arizona. Green stems poke from coconut ...

After the posts are driven into the ground in a row, tomato plants are planted between the posts, and then twine is woven in ...

but floating row covers and cloches can only do so much. To avoid frost damage, all tomatoes, even the green ones, should be ...