Winter radishes are a must for radish lovers. ‘Round Black Spanish’, also known as ‘Noir Gros Rond d’Hiver’, grown in the U.S. since the 1800s, is an extra large, winter radish that adds spiciness to raw or cooked dishes; spiciness declines when cooked. Winter radishes require a shortening day length and cool temperatures to mature the edible root; sow after mid-summer and into early fall. They can be stored for long periods.