Raphanus sativus (Radish)

One of the workhorses for the garden, Radishes (Raphanus sativus) are annual and biennial edible root vegetables grown for their colorful, crunchy, peppery roots. Radishes are a cool-season crop that is quick, fun, and easy to grow from seed and ready to eat in as little as four weeks.

• Radish is likely native to Southeast Asia. Ancient Greeks and Romans used it for food and medicinal purposes about 2,500 years ago. Today, hundreds of radish varieties are broadly distributed around the world.
• Radishes are a member of the Brassicaceae or cabbage family, which includes broccoli, cabbage, cauliflower, kale, collards, and horseradish.
• Most familiar radishes are round, short, red, or bicolor red-white, but long and narrow varieties are available, as well as black, white, yellow, pink, or purple radishes.
• Certain Radish varieties do not produce fleshy roots but are grown for their crunchy seedpods.
• The entire Radish plant is edible and can be eaten raw or cooked.
• Because Radishes are quick to mature, they can be sown as a catch crop between rows of slower-growing vegetables (peas, potatoes).
• Radishes can also be used as row markers for slow-germinating crops (Parsnip, onions) – they mark out the row where the other crops have been sown and are harvested before they can hinder the main crop.

Choosing Radishes

There are 2 main categories of Radishes: spring Radishes and winter Radishes.

Spring Radishes

• Spring Radishes love cool temperatures and are the most common Radishes.
• They are best when they are smaller than 1 inch in diameter (2.5 cm).
• They grow up to 6-18 in. tall (15-45 cm) and 6-9 in. wide (15-22 cm).
• They are ready to harvest in just 3-6 weeks.
• They can be planted in spring or in fall.

Winter Radishes

• Grown in late summer or fall, Winter Radishes can be eaten fresh or stored over winter.
• Also known as oriental Radishes, they are usually bigger than spring Radishes when they are mature.
• Radishes may reach 12-24 in. in length (30-60 cm) and 3 in. in diameter (7 cm).
• Radish plants are also larger than spring Radishes, reaching 2 ft. in height and spread (60 cm).
• Winter Radishes are ready to harvest between 45-70 days, depending on the variety.

Radish Health Benefits

• While Radishes make a flavorful addition to salads and various dishes, they can also provide some health benefits.
• Radishes contain a good amount of vitamin C and are a great source of antioxidants (catechin, pyrogallol, vanillic acid), and other phenolic compounds.
• Radishes are also rich in antioxidants and minerals such as calcium and potassium.
• Radishes can help regulate blood sugar levels, help the liver detoxify, lower blood pressure and reduce your risks for heart disease.
• Aside from being packed with vitamins and minerals, Radishes are very low in carbs.

Growing Radishes

• Radishes grow up to 2-3 ft. tall (60-90 cm) and 1-2 ft. wide (30-60 cm), depending on the variety.
• Radishes perform best in full sun or light shade, ideally in light, rich, near-neutral (pH between 5.5 and 6.8), and evenly moist but well-drained soil.
• The secret to mild, tender radishes is rapid growth. Keep the soil moist for fleshy, tasty Radishes that do not split.
• Most Radishes do best in cool conditions. Temperatures between 50-65°F (10-18°C) produce the best Radishes. Growth above 75°F (24°C) is poor and intense heat will turn them bitter.
• Plant Radishes as soon as soil can be worked in spring. Make small plantings weekly until the hot summer months so that there is a succession of crops.
• Add organic matter before sowing. Avoid fresh manure or fertilizers high in nitrogen, as they would promote lush foliage at the expense of radish roots.
• Radishes are ready to harvest 30-45 days from planting. Harvest them when young so that they do not become woody.
• Select a permanent location carefully since asparagus plants will produce for 20 years or more.
• Plant in edible or vegetable gardens, along borders for mass planting, or in small groups. If your soil is heavy or poorly drained, plant Radishes in raised beds.
• Mulch to retain moisture and control weeds.
• Do not rotate Radish with cabbage, cauliflower, ‘Brussels sprouts, kohlrabi, broccoli, or turnip, since all are members of the Cabbage family.
• Pests: Radishes may be affected by flea beetles, slugs and snails, and cabbage root fly.
• Diseases: Radishes may be affected by brassica downy mildew and by brassica white blister, club root, damping off, fungal leaf spot, and virus diseases.
• Find where Raphanus sativus species is invasive in the United States.

Radish Companion Planting

• Excellent companion plants for radishes are beets, bush beans, carrots, chervil, cucumber, lettuce, melons, nasturtium, parsnip, peas, pole beans, spinach, and members of the squash family.
• Radishes are a good companion to have in the garden as they deter cabbage maggot, cucumber beetle, rust fly, spider mite, squash bug, and squash vine borer.
• Radishes deter spider mites when planted close to tomatoes and protect all members of the squash family from the squash borers.
• Radish attracts leaf miners away from spinach.
• Chervil and nasturtium are known to improve the growth and flavor of radishes
• Radishes grown with lettuce become more tender and are particularly succulent.
• Bad companion plants for radishes include cabbage, cauliflower, kohlrabi, broccoli, turnips, and Brussels sprouts, as well as the hyssop plant.