Before you start marking and digging rows, plan the layout and spacing to maximize your garden area. Measure the overall garden area so you can divide the space into rows. The size and spacing of the rows depends heavily on what you plant. Small vegetables, such as carrots (Daucus carota), grow in narrow rows and only need around 12 to 18 inches between rows. Larger vegetable plants, such as corn (Zea mays), take up more space and need 24 to 48 inches between rows. If you plan to use a rototiller to control weeds, your row spacing needs to be at least as wide as the machine.