Radish sprouts mature quickly and are a nutritious source of green vegetables. Like radish roots, radish sprouts have a distinct spicy flavor. The best tips for sprouting radish seeds is to use fresh untreated seeds, rinse the seeds frequently during sprouting and provide them with a warm place to germinate and mature.
One of the best tips for sprouting radish seeds successfully is to purchase radish seeds sold specifically for sprouting. Seeds sold for planting are often treated with chemicals to prevent them from rotting in the soil during germination. Seeds for sprouting, however, typically are untreated. As an alternative, radish seeds can be collected from radish plants in late summer.
A mason jar can provide a suitable sprouting container. Radish seeds swell to six times their size when fully sprouted, so a jar, large enough to hold the fully sprouted seeds should be used. The lid must have holes in it to allow air circulation and to aid in rinsing the seeds. Stores sell mesh lids specifically for sprouting, or one can be created by punching holes in a standard canning lid.
Radish sprouts take about six days to mature, though once softened, the seeds can be eaten at any stage of development. The younger seeds and radish sprouts are more tender than ones harvested later. Growing radish sprouts at home is a quick way to grow tasty greens, even in winter.
The seeds should be placed in the jar and soaked in room temperature water for eight to 12 hours, then drained. The jar should be laid on its side so the radish seeds spread out along the bottom. The seeds and developing sprouts should be rinsed every eight to 12 hours, and the jar should be kept between 70 and 75°F (21 to 23°C).
Radish sprouts require a dimly lit area for the first two to three days. After that, they can be moved to an area that gets filtered light. The sprouts can grow successfully in dim light until ready to eat, however. Sprouts grown in a lit area turn green, while those kept in the dark stay white.
After six days, or when the sprouts are the desired length, they are removed from the jar and drained. Radish sprouts can add a spicy note to fresh salads and sandwiches, and can be eaten alone. They also can be added to stir fries and vegetable dishes, but they should be cooked only lightly to preserve the delicate flavor.