Fast-growing radishes tend to mature all at the same time, so sow small amounts every 2-3 weeks from early spring to late summer for a continuous crop. Rake your soil to remove any stones and lumps and create a shallow trench ½ in (1 cm) deep with a cane. Sow seed thinly at 1 in (2.5 cm) intervals along the row to reduce the need for thinning later; cover them with soil and water well. Space rows 6 in (15 cm) apart. Make summer sowings in light shade to help stop plants running to seed (bolting). Radishes can also be sown in large pots, with seeds spaced at 1 in (2.5 cm) intervals.
Seedlings grow very rapidly and need to be thinned to 1 in (2.5 cm) apart promptly to avoid checking their growth. Thinning radish seedlings helps ensure that the radishes you harvest are plump and juicy. Water radishes in the soil thoroughly once a week during dry weather and those in pots daily to prevent them bolting and keep roots succulent. Grow under fleece to prevent problems with flea beetle.
Pick radishes by pulling them from the soil by their leaves as soon as they are the size of large marbles. Harvest quickly because plants tend to bolt rapidly and mature roots become woody. Radishes make a satisfying snack or a colorful addition to salads.