Direct sow in early May in rows spaced 10" apart. Thin small radish seedlings to 2-4" apart, depending on the variety. Keep watered, especially as the season warms up. Harvest radishes as soon as they are round, there is a small window to harvest them before they split. Store radishes without the top to keep roots firm. (Tops are enjoyable in a saute or braising mix.) Radishes are fast growing, so plant in successions to have a steady crop.