Tomato seedlings should be planted 2 feet apart, according to the Old Farmer's Almanac. The wide spacing accommodates mature plants and allows enough room for wire cages, which stake the tall plants and provide protection from birds and animals.
About two weeks before planting tomatoes, the soil should be tilled up to 12 inches down and compost or fertilizer should be added. Seedlings should be planted after the last frost, with the root ball completely covered and the lowest leaves above the soil. Wire cages or stakes should be installed at the time of planting to avoid disturbing the mature root system.