Radishes are among the easiest and fastest vegetables to grow, making them a great starter crop for new gardeners. The plants are always grown from seed sown directly in the garden. The typical supermarket radish is small, round and red. But radish comes in a wide variety of colors, shapes and sizes. Popular varieties include French Breakfast, Cherry Belle and White Icicle.
Radishes need well-drained soil that has been worked several inches deeper than the length of the root. Begin planting seeds two weeks before the last spring frost, and again every two weeks for a continual harvest. Plant seeds 1/2" deep and 1" apart in rows spaced 10" to 15" apart. Cover the seeds by gently pushing the soil back on top of them. Water well.
When radish seedlings emerge in three to four days, thin to one plant every 3" to 4" by carefully pulling the plants by their stems. Use the young seedlings in salads. Radishes need about 1" of water per week or they become woody and bitter. Add a thick layer of mulch around the base of the plants to preserve moisture and prevent weeds.
Radishes are ready to harvest 21 to 60 days after sowing. The roots are mature when they push out of the ground a little and measure about 1" across. Radishes need to be harvested quickly once they reach maturity or they will crack, hollow out and taste bitter. To harvest, pull up by the base of the stems.