Radishes are a cool season vegetable that can mature very quickly. The small, round varieties will get woody if grown in hot temperatures.
Radishes are direct seeded in the garden. They can be started very early in the spring, as soon as the ground is relatively dry and can be worked and again in late fall, in cold frames.. Radishes can be squeezed in between other plants and are good at loosening and cultivating soil for slower sprouting vegetables, like carrots.
Sow seeds 1/4 to ½ inch deep. You’ll want at least and 2 inches between plants, but seedlings can be thinned and eaten when they are an inch or two tall.
Spring Radishes - The fast maturing, round radishes are ready for harvest in 3-4 weeks. You’ll usually see the top portion of the radish poking up through the soil. When it appears to be almost an inch across, it is ready to pick. Radishes can be harvested by pulling or by gently loosening the surrounding soil. Don’t let mature radishes sit in the ground or they will get either woody or spongy.
Winter Radishes - The long, Asian radish varieties take longer to mature, sometimes up to 3 months. They should be harvested before the ground freezes and can be stored for several months.
The thinned plants of all varieties can be used as salad greens or on sandwiches or floating on soups.
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Pests and Problems:
Cabbage Root Maggots are more of a problem in northern gardens, where they will tunnel into radishes.
Cutworms can also feed on radishes.
Flea beetles will make Swiss cheese of radish leaves, but don’t injure the bulb.
Monitor to catch these insects before they destroy the whole crop. You can avoid them almost entirely by growing your radishes under row covers.
Radishes decline in quality when the temperature warms. They can get tough and woody or spongy with hollow centers. Once a radish bolts, or goes to seed, the bulb stops forming.