Garden Crops Posted By: Ben Butler August 13, 2009 @ 4:49 am Today's Local News Tweet Share Email Corn and soybeans could be hurt by an early frost, but that’s not the case for certain garden crops. Keokuk County Extension Director Gary Bickmeier says things like lettuce, broccoli, and spinach are slightly behind the average, but remain hearty during colder weather. Bickmeier says other things like tomatoes must be picked once they turn green and then ripen indoors.