How to Plant, Grow, and Harvest Radishes

Radishes are one of the easiest crops to grow. The radish is a cool-weather crop. Radishes can be harvested in spring or fall for the best flavor and texture. Radish is ready to eat as few as three weeks after sowing seeds. It is easy to understand why radishes are a favorite of home gardeners. In this article, you'll learn how to plant, grow, and harvest radishes.

How to Plant Radishes

Sow radish seeds in well-worked soil after the danger of frost in early spring and again in late summer for a fall crop. In frost-free areas, sow in the fall. Thinly sow in rows about 6" apart. Cover with ½" of fine soil; firm lightly and keep evenly moist. The radish seedlings will emerge in 4-6 days. Depending on the spacing, thin so the radishes are about 2" apart. Sow winter radishes in midsummer for late fall and winter use. They can grow large with several inches of root showing above ground.

How to Grow Radishes

• Keep weeds under control during the growing season. Weeds compete with plants for water, space, and nutrients, so control them by cultivating them often or using a mulch to prevent their seeds from germinating.
• Water continuously and evenly. Avoid over-fertilizing radish plants.
• Keep plants well-watered during dry periods to promote uninterrupted growth. Plants need about 1 inch of rain per week during the growing season. Use a rain gauge to check if you need to add water. It’s best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening to minimize disease problems. Keep the soil moist but not saturated.
• Monitor for pests and diseases.

Tips for Harvesting and Preserving Radishes

• Pull spring radishes about 25 days after planting when they are the proper size for the type. If you wait too long to harvest, they will become pithy. Push back the soil to see if they have formed bulbs, and taste one or two to see if they are ready. Finish harvesting before warm weather comes.
• Cut off the tops and store them in plastic bags in the refrigerator at 32-40 degrees F for up to 3 weeks.
• Harvest winter or fall radishes as needed in fall. Dig all remaining roots before the ground freezes and store them throughout the winter (use as needed).
• Radishes may be eaten raw in salads or sautéed in butter with salt, pepper and herbs as a side dish. Winter radishes may be cooked like turnips or used in stir fry. They may also be pickled.

Radish Planting and Spacing

• Sow radish seeds ½ inch (12mm) deep and 1 inch (2.5cm) apart; depending on the variety, thin, successful seedlings 2 to 4 inches (2.5-10cm) apart in wide rows.
• Plant winter radishes 3 to 4 inches apart.
• Radish seeds are so small that they certainly require thinning once seedlings appear.
• Radish germination takes 3 to 6 days. Once seedlings appear, they can be thinned to proper spacing. Use a garden scissor to cut green tops off at the soil level.
• Allow greater room for winter varieties.
• Space single rows or mounded ridges 10 to 16 inches (25-40cm) apart.

How Many Radishes Grow Per Seed

One radish seed produces only one radish; however, when it bolts or goes to seed, each radish produces many seeds. When the radish goes to seed, it forms a flower, then a green pod that eventually turns brown as it dries out. Once the pod dries out, you can harvest and replant the seeds.

Planting Radishes Using Seed Tape

Radish seeds are very small, and spacing is important to ensure that the underground bulb has enough space to mature fully. There are several ways to help ensure proper spacing, including seed tape. Seed tape is a water-soluble tape that encases the seed at the correct spacing to ensure each seed has enough room to form a bulb.

Growing Radishes in a Raised Bed or Pot

Radishes are perfect for container growing. Most varieties require little space and can easily be grown in a raised bed or pot. Use a commercial potting mix rather than garden soil. Space the plants as directed on the seed pack, place the raised bed or container in a sunny location and keep the soil moist but not wet.

Watering Radishes

It is important to ensure the young radish plants get enough water; watering your garden efficiently is the best way to do that. If the planting does not get one inch of rain each week, soak the soil thoroughly at least once a week. If your soil is sandy, water more than once a week. One inch of water will wet sandy soil to a depth of ten inches and heavy clay soil to six inches. A soaker hose is a great way to water to help ensure the water reaches the soil while allowing you to avoid wetting the leaves.

Companion Planting Radishes

We like to companion plant as often as possible. Companion planting saves space and can act as a weed block and deter some pests and diseases. Good radish companion plants include lettuces, tomatoes, carrots, onions, peppers, peas, cucumbers, spinach, and herbs like dill, mint, and oregano. Do not plant radishes with plants from the Brassicas family.

Common Disease Problems

Alternaria Leaf Spot is a small, round, reddish brown spot with white to gray centers on the upper surface of the leaves. The lesions may encircle the stems and cause wilt. This disease is worse in warm, wet, or very humid weather. How to solve it: Avoid getting water on the foliage. Remove infected plant parts, and do not work around wet plants. Provide plenty of air circulation.

Black Root: This mostly affects long-rooted radishes. A soil-borne fungus causes it and causes lesions that expand and girdle roots. How to solve it: Rotate crops. If the problem is persistent, try planting round varieties.

Downy Mildew: This fungus causes whitish-gray patches on the undersides and, eventually, both sides of the leaves.  How to solve this problem: Rotate crops with plants from different families. Avoid overhead watering. Provide adequate air circulation; do not overcrowd plants. Do not work around plants when they are wet.

Scab: This disease causes brown and yellow circular lesions on the roots. The lesions become sunken and cracked, irregular, and coalesce.  How to solve: Do not plant radishes or other brassica family members in the same area for at least four years. Try container growing.

Yellows: Plants are stunted and develop yellow leaves. Leafhoppers spread this virus-like condition. How to solve it: Remove infected plants and control leafhoppers. Also, weeds in the area that serve as alternate hosts for the disease should be removed.

Common Pest and Cultural Problems

Aphids: Greenish, red, black, or peach-colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. How to solve: Introduce or attract natural predators into your garden, such as lady beetles and wasps, which feed on aphids. You can also wash them off with a strong spray or use an insecticidal soap.

Cabbage Root Maggot: These insects live in the soil and feed off the plant roots.  How to solve: Your Cooperative Extension Service may recommend a soil drench before planting. A flat band or collar of thick paper around the base of the plants, or floating row covers, may help prevent the adult flies from laying eggs at the base of the stems.

Cracked roots may occur when they are not harvested early enough.

Flea Beetles: These small hopping beetles feed on plant foliage. To solve this problem, Rotate crops with plants in a different plant family and use floating row covers to prevent damage to young foliage.

Leafhoppers: Leafhoppers damage leaves, stunt growth, and spread disease. To solve them, Remove plant debris, use insecticidal soaps, and consult your Cooperative Extension Service for other insecticide recommendations.

Radish FAQs

Why did my radish not form a bulb? Radish roots are sensitive to overcrowding and hot weather, and the soil may not have been loose enough.

Why are my radishes woody? Radishes are a cool season crop that will turn woody when harvested too late.

My radishes are blooming! Your radishes have bolted, which often occurs when the weather becomes hot. At this point, you have two choices. Either pull them up and discard them, as they are not edible, or allow them to continue bolting and produce seeds to harvest.

Can I eat the radishes that are thinned out? Yes, radish sprouts are edible. In fact, you can buy radish seeds in bulk to sprout and eat as microgreens.

MORE GARDENING HELP

 If you're looking for even more detailed information, check out our gardening section of the website. If you still have questions about planting, growing, and harvesting radishes, let me know in the comments section below or contact me through our private Facebook group.

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