The radish is a cool-weather crop. Sow radishes in the garden 2 to 3 weeks before average date of the last frost in spring. Sow succession crops every 2 weeks in spring and in autumn. Radishes require 22 to 70 days to come to harvest. Complete the harvest before the weather grows warm. In mild winter regions, grow radishes in late autumn and early winter.
Description. The radish is a hardy cool-weather annual. Radish roots can be globe shaped or long and tapered. Roots can be white, red, or black colored. Radishes form a rosette of lobed leaves on stems rising from the root.
Yield. Plant 15 radishes per household member each month.
Site. Grow radishes in full sun or partial shade. Plant radishes in loose, well-drained soil. Remove soil lumps, rocks, and roots from radish planting beds. Obstructions can cause roots to grow malformed. Add organic matter to planting beds before sowing radishes. Radishes prefer a soil pH of 5.5 to 6.8.
Planting time. Radishes are a cool-weather crop. Sow radishes in the garden 2 to 3 weeks before average date of the last frost in spring. Sow succession crops every 2 weeks in spring and in autumn. Two or more crops can be grown in spring. Radishes require 22 to 70 days to come to harvest. Complete the harvest before the weather grows warm. Warm weather can result in small roots. Long days may also cause radishes to flower; plant radishes during the shorter days of spring and autumn. In mild winter regions, grow radishes in late autumn and early winter. Radishes can withstand frost.
Planting and spacing. Sow radish seed ½ inch deep and 1 inch apart; thin successful seedlings from 1 to 4 inches apart in wide rows depending upon the variety. Allow greater room for winter varieties. Space single rows or mounded ridges 10 to 16 inches apart.
Water and feeding. Keep radish planting beds moist but not wet. Even, regular watering will result in quick growth. Radishes that receive too little water will become woody tasting. Prepare planting beds with aged compost. Side dress radishes with aged compost at midseason.
Companion plants. Cucumbers, lettuce, nasturtiums, peas, peppers.
Care. Radishes will bolt or go to seed if grown during the long days of summer. Cover plants in midsummer so that they get 8 rather than 12 hours of sunlight. Keep radishes evenly watered so that they grow quickly. Slow growth will cause radishes to taste hot.
Container growing. Radishes can be grown in containers. Sow radishes in containers at least 6 inches deep. Plant radishes in round containers in concentric circles. Move containers to cool locations if the weather grows warm.
Pests. Radishes can be attacked by aphids and root maggots. Pinch out infested foliage. Usually radishes grow so quickly that pests are not a problem.
Diseases. Radishes have no serious disease problems.
Harvest. Spring radishes require 20 to 30 days to reach harvest. Winter radishes require 50 to 60 days to reach harvest. Radishes are ready for harvest when roots reach 1 inch across. Lift the whole plant when radishes are the right size. Lift a few or push the soil aside gently to decide if they are large enough to harvest. Do not leave radishes in the ground too long or they will become pithy.
Varieties. Radishes can be grown for spring or winter crops. Spring varieties are the common small red varieties. Winter radishes are larger, oblong and can grow 8 to 9 inches long. Spring crop: Cherry Belle (22 days); Burpee White (25 days). Winter crop: Black Spanish (55 days); White Chinese (60 days).
Storing and preserving. Radishes will keep in the refrigerator for 1 to 2 weeks. You can sprout radish seeds.
Common name. Radish
Botanical name. Raphanus sativus (spring radish); Raphanus sativus longipinnatus (winter radish)
Origin. Temperate regions of Asia