Joseph Masabni, Assistant Professor and Extension Horticulturist, The Texas A&M University System
Radishes are often the first vegetable harvested from a spring garden. They are a cool-season crop and do not do well in the hot summer months.
Radishes are grown for the root, which usually is eaten raw, alone, or in salads. The leaves can also be eaten, especially when they are young and tender. Radishes are colorful and good for you. For this vegetable, a row 10 feet long is adequate for a family of four.
Site selection
Radishes can grow in partial shade, require very little room, and mature quickly. They are well suited to small gardens, flower beds, and containers.
Soil preparation, fertilizing
Radishes need loose, well-drained soil to allow the roots to expand easily. If the soil is crusty, the roots become misshapen.
To prepare the soil, remove rocks, trash, and large sticks from the planting area. Small pieces of plant material such as grass and leaves can be mixed into the soil to make it richer.
Spade the soil to a depth of 8 to 12 inches. Turn each shovelful completely over so all the plant material is covered. Scatter 1 cup of fertilizer, such as 10-20-10, on the soil for each 10 feet of row to be planted. Rake the soil until it is smooth and work up the beds as shown in Figure 1.
Figure 1. The 4-inch ridges are very important in low, poorly drained areas. They allow the soil to drain and let air enter the soil. Space the ridges farther apart if the radishes are to be followed by a summer crop. Plant two or more rows of radishes on each ridge.
Varieties
Radishes can be of the red or the white variety (Fig. 2). Some recommended red varieties are Champion, Cherry Belle, Early Scarlet, and Early Scarlet Globe. Recommended white varieties include Chinese White Winter, Summer Cross and White Icicle.
Figure 2. Red radishes, left, the most popular type, are round or oval. The white type, right, can be globe shaped or long like a carrot.
Planting
Plant the seeds as soon as the soil can be worked in the spring. Using a hoe handle, stick, or similar object, make a furrow ½ inch deep down the center of the ridge (Fig. 3). Plant the seeds ½ inch deep and 1 inch apart in the row. Cover them lightly with loose soil, and sprinkle them with water. The plants should be up in 4 to 6 days.
Make several plantings 8 to 10 days apart for a steady supply of radishes. They will be ready for harvest about 4 to 5 weeks from planting.
Figure 3. Plant seeds ½ inch deep and 1 inch apart in the row.
Care during the season
Scratch the soil around the plants lightly with a rake or hand tool to keep the soil from crusting. Water the plants well weekly if it does not rain.
Begin thinning the radishes when the roots start expanding. Pull every other plant (Fig. 4). The larger roots can be eaten; those left in the row will continue to get bigger without being crowded. Keep the radishes free of weeds, which rob weak root systems of nutrients and moisture.
Figure 4. To thin radishes, pull every other plant.
Harvesting
Harvest radishes when they are young and tender (Fig. 5). If left in the ground too long, they get tough, hot tasting, and stringy.
To harvest, pull the radishes, cut off the tops and small roots, and put those in a compost pile. Wash the radishes well and place them in plastic bags in the refrigerator. They will keep 2 to 3 weeks or until the next planting is ready for harvest.
Figure 5. The center, left, should be solid with no cracks. Right, an over mature radish with a pithy or cracked center.
Insects
Many insecticides are available at garden centers. Sevin is a synthetic insecticide; organic options include sulfur and Bt-based insecticides. Sulfur also has fungicidal properties that help in controlling many diseases.
Before using a pesticide, read the label. Always follow cautions, warnings and directions.
Diseases
Because radishes mature so quickly, diseases usually are not a problem. Check the plants daily and treat them with an approved fungicide if diseases appear. Neem oil, sulfur, and other fungicides are available for use. Always follow the label directions.
Cleanup
After the radishes get too old or start going to seed, pull and place them in a compost pile if the soil is to be replanted soon. If the soil is to be left idle, the old radishes and tops can be spaded into the soil, helping to build the soil.
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