Radishes (Raphanus sativus) are edible roots in the Brassicaceae family of plants and are closely related to cabbage, kale and broccoli. They have high nutritional value and find numerous culinary, industrial and cultural uses. Radishes vary in size, color and taste depending on their specific variety. They are easy to grow and typically harvest within 30 days of sowing.
Radishes make the swollen part of the roots of the annual, erect, herbaceous Raphanus savitus group of plants that grow up to 40 inches tall. Roots are purple, red, yellow, green, white or black. Leaves are without stipules and range between 2 and 12 inches in length. Flowers are bisexual, fragrant, lilac to white and up to 1/2 inch in diameter.
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Size, Weight and Shape
Weights and shapes vary between different varieties of radishes. Western small white, red and red and white radishes measure about 1 inch in diameter while larger white or black varieties are up to 4 inches in diameter. Smaller radishes are typically round and oval while larger are ellipsoid, globose and cylindrical. Radishes weigh a fraction of an ounce for their smallest varieties to more than 50 lbs. for larger types. The giant Japanese Sakurajima radish can weigh up to 100 lbs. and measure up to 23 inches in length.
Constituents and Nutritional Value
Radishes contain about 94 percent water, 5 percent carbohydrates, 0.5 percent protein and 0.1 percent fat, according to "Guide to Cultivated Plants." Calcium, iron, phosphorous and vitamins A, B and C are also constituents. A 3 1/2 oz. radish yields about 16 calories of energy.
Types and Varieties
Common radish varieties include Cherry Bell, French Breakfast and April Cross. Cherry Bell is a fast-growing variety that produces red, round radishes within 22 days of sowing. French Breakfast takes 23 days to ripen into oblong red radishes with characteristic white roots. April Cross takes 56 days to ripen to white radishes that range between 12 and 16 inches in length. "Taylor's Guide to Heirloom Vegetables" recommends China Rose, French Golden, Long Black Spanish and Round Black Spanish varieties of radish.
Pests and Diseases
Cabbage caterpillars, flea beetles, cutworms and slugs are common pests that attack both the roots and leaves of radishes. Diseases radishes are susceptible to include alternaria leaf spot and clubroot.