AMES, Iowa — Radish is a cool-season, fast-maturing, easy-to-grow vegetable. Garden radishes can be grown wherever there is sun and moist, fertile soil, even on the smallest city lot. Gardeners with questions about growing radishes and other cool-season vegetables should contact the horticulturists with Iowa State University Extension and Outreach at firstname.lastname@example.org or 515-294-3108.
Suggested radish varieties (cultivars) for home gardens include:
Radishes can be planted as soon as the ground can be worked properly in spring. This is often late March in southern Iowa and mid-April in northern counties. Successive plantings can be made every 7 to 10 days through May. Radish plants flower and their roots become pungent with the onset of hot weather. Several plantings can also be made in late summer (late August to late September) for a fall crop.
Sow radish seeds ½ inch deep in rows that are 12 inches apart. When the seedlings emerge, thin the planting so remaining plants are 2 inches apart.
Radishes can be harvested three to five weeks after planting. Periodically check their development by pulling one or two plants as they approach maturity. Harvest radishes when roots reach useable size (about 1 inch in diameter). Radishes can be stored in the refrigerator for two to three weeks. Prior to storage, cut off the foliage to within ½ inch of the roots. Radishes get pithy and hot when harvested too late.
Excessive nitrogen, the rapid onset of hot weather or overcrowding may produce plants that are all tops (lush foliage, little or no root development).
Misshapen roots and hot, pithy radishes are other problems that may be encountered when growing radishes. Overcrowding produces small, misshapen roots. Hot, pithy radishes may be result of hot weather or harvesting too late.