Radish seed are small, oval-shaped seeds typically ranging from 1 to 3 millimeters in size. They are commonly dark brown to black in color, although some varieties may have lighter shades. These seeds are smooth and slightly shiny in texture. When planted, radish seed germinate relatively quickly, typically within a week under optimal conditions. Radish seed are renowned for their ability to produce rapid growth, often yielding mature radishes within 3 to 4 weeks after planting.