The Radish Round Black Spanish, 'Raphanus sativus', is a winter radish with black skin and white flesh. Radish lovers should try this often neglected group of winter radishes. The large roots are excellent for slices on sandwiches or in salads. The flesh has a medium-hot flavor and they can be stored for a long time. . In cold climates, plant in mid-summer for fall harvest. In mild climates, plant in late fall for fall and winter harvest. Radishes prefer loose, light soil with a fair amount of organic material. Harvest when the radish is 3 to 4 inches across or smaller. Bigger radishes get pithy and hot. ... additional info