How Does a Radish Grow?

The Radish

The radish is a root vegetable. Though the root is the main vegetable, radish leaves and seeds are also edible. Small summer varieties usually mature in 3 to 4 weeks. Large winter varieties may take up to 4 months to mature. Radishes come in color types: red, white, purple and black. Their shapes range from round to oblong. These easy-grow vegetables are popular around the world for cooking, fresh salads and garnishes.

Growing Summer Radishes

Spring or summer radishes are a cool season crop. Seeds are planted directly in the ground. Sunny locations with loose or sandy soil encourage fast germination. Small red radishes mature in about 3 weeks and are one of the first spring crops. Because they mature so quickly, these radishes are often planted in succession about a week apart. This ensures a steady harvest of radishes. Larger white radishes take longer to mature. Some are the size and shape of a carrot and are harvested at 6 to 8 weeks. Radishes are good companion crops and grow with lettuce, onions and other salad vegetables.
The National Gardening Association (NGA) recommends planting summer radishes as cultivators or trap crops. Radishes act as cultivators for other plants by leaving holes when they are harvested. The NGA suggests leaving some radishes in the ground after they reach maturity. When the overdue radishes are pulled out, they leave big holes. These holes give the other plants room to grow in clay or other resistant ground (see Resources below).
As trap crops, these early vegetables are the first target of invading garden bugs. Leafhoppers, root maggots and other pests attack the early vegetables. Gardeners pull out the infested plants and throw out both plants and pests.

Growing Winter Radishes

Winter radishes are not as sun-tolerant as summer radishes. They thrive in the shorter days and cooler weather of winter. Their colors are usually white, green and black. The varieties are larger than summer radishes. Shapes are round, oblong, thick or slender. These varieties are sown directly in the ground. The University of Illinois Extension recommends planting winter varieties in midsummer to late summer. As the radishes begin growing, thinning them 2 to 4 inches or more apart to allow growing room is a good idea. The plants need extra room as some winter radishes grow over a foot long and weight over 5 lbs. They mature slowly, from 2 to 4 months depending on the variety. These radishes are often left in the garden in fall weather, then harvested before the ground freezes. Winter radishes keep well in refrigeration after harvest.

Resources

• National Gardening Association: Radish
• Watch Your Garden Grow: Radish