Raphanus

Raphanus is the botanical name for the Radish. There are two different types of Radishes; the spring Radish, which is commonly used in salads, and the Oriental or winter Radish, which isn't as well known, but is becoming more popular.
Spring Radish (R. sativus) - This hardy annual loves cooler weather. It forms small rosettes of rough, dark green leaves and enlarged, edible roots. The foliage may be mixed and cooked with Turnip or Mustard Greens when it is young and tender. Young spring Radishes are ordinarily eaten raw, before they become pithy or pungent with age. There are several different kinds, which vary in color and shape. Some are oval, cylindrical, round, or tapered like an icicle. Each type has a wide range of colors; white, red, white and red, pink and white or a combination of white, rose and purple.
Winter Radish (R. sativus variety longipinnatus) - The winter Radish is also known as the Oriental Radish and Daikon. Winter Radishes aren't regularly grown in the U.S., although many of the old standby winter varieties have been grown for decades by experienced gardeners. The name comes from the practice of gathering the roots in the winter.

Pot Cultivation

Spring Radish - Radishes prefer sandy or sandy loam soil that is rich in humus. If your soil is heavy and dense, build raised beds with good drainage. These plants require rich, well-cultivated soil so that they will grow quickly and have crisp roots. Once the seedlings have developed four to six leaves, douse them with manure tea or soluble fertilizer to activate rapid growth. Radishes should be ready to pull 32 weeks after seedlings appear, when grown under favorable conditions. Begin pulling the Radishes when they are barely large enough to eat, so that there is plenty of room for the rest to grow with minimal competition.

Winter Radish - These Radishes need the same soil requirements as the Spring Radishes. The short nights of summer encourage flowering, so plant during late summer or later to prevent them from going to seed. In cold climates, mulch the plants with straw or pine needles. Tack down chicken wire to keep the mulch from blowing away. The roots will continue to grow larger and become sweeter. In climates with mild winters, no mulch is needed. Begin harvesting Winter Radishes when the roots are still small in order to provide plenty of room for the rest to grow large. The young greens are also edible. Winter-sweetened roots are great when sliced and added to soups or salads.

Propagation

Spring Radish - In the spring, as soon as the soil can be worked, sow seeds directly outdoors in sand or sandy loam. When planting on heavy soil, build up the beds as described in the potting section and dig furrows, 2 inches deep and fill with sand almost to the top. Sprinkle in the seeds and cover with c - or 3 -inch of sand. The seedlings will need to be thinned to a foot apart. Plant only a few feet of row at a time, making successive plantings every 2 weeks until mid-spring. Summer plantings will bolt to seed before they form roots large enough to eat. Plantings that are made in early autumn will do well. Winter Radish - Sow seeds in late summer or later to prevent them from going to seed. The plants should be thinned 6 to 12 inches apart. In the North, direct-seed in cold frames to add a month to the growing season. Otherwise, plant the seeds directly outside. (In order to offer protection from the birds, it may be necessary to place netting supported by short sticks over your seeds.)