Keep seeds moist until they sprout. Thin the plants to an inch apart soon after they come up. Harvest radishes 3 to 4 weeks after planting. If they are left in the ground too long, they may split, crack, or become pithy. They are best eaten as soon as possible after harvesting.
Oriental radishes are much bigger than most of the radishes grown in the United States.
Oriental varieties include Daikon and other types, many of which grow to more than a pound. The Sakuajima Mammoth radish has been known to top 100 pounds. These jumbo radishes generally mature in about 60 to 70 days and can be pickled, breaded and fried in oil or sliced and slightly cooked and added to many stir fry dishes. Oriental radishes are best planted in late summer, as they bolt with June's long days. A few pests occasionally attack radishes when the weather turns warm, including flea beetles and cabbage maggots.