8-12 Days to microgreen harvest. Raphanus Raphanistrum Sativus. White Stem Radish Seeds. Annual, Open Pollinated, Heirloom. This variety of radish is grown to be harvested as microgreens, and generally isn't grown to full maturity. The seedlings have crisp white stems with green leaves. They are quick growing, crisp, tender, and have a nice flavor and pungency. Approximately 3,000 seeds / oz.