Radishes thrive in full sun, though a little partial shade won't hurt, as long as they soak up four to six hours of sunlight a day. Plant seeds about ¼ to ½-inch deep for the smaller radishes, and up to an inch for the big daikon types. Keep them spaced 1 to 3 inches apart for little roots and 4 to 6 inches for the giants. If you have a small yard or balcony, you can also grow radishes in containers. Plant a fresh batch every week or two, and you'll have a steady fall harvest to snack on or share.