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Radishes: Planting, Growing, and Harvesting Radishes | The Old Farmer's Almanac

Radishes

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radishes at a roadside market

Photo Credit
Annette McCarthy
Botanical Name
Raphanus sativus
Plant Type
Sun Exposure
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Planting, Growing, and Harvesting Radishes

The Editors
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Radishes are hardy root vegetables grown for their crisp, colorful and peppery roots. They can be planted multiple times in a season—and be ready to harvest as soon as three weeks! Find out how to grow radishes and how to tell when they’re at their peak.

About Radishes

Radishes are an annual root vegetable and a member of the Brassicaceae or cabbage family, which includes broccoli, cabbage, cauliflower, kale, collards, and, as the name suggests, horseradish. The entire plant is edible—from root to leaves—and can be enjoyed raw or cooked. (See Cooking notes below.)

Seeds can be planted in both the spring and the fall, but sowing should be suspended when warm temperatures arrive (70 degrees or higher); this causes radishes to bolt, making them essentially useless. Otherwise, radishes are one of the easiest vegetables to grow. 

Because radishes mature so quickly, you can really sow them anywhere there is an empty space or sow in between rows of other vegetables such as carrots or beets. Radishes also happen to make excellent companion plants to help deter pests from other vegetables.

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Planting

Choose a sunny spot that gets at least six hours of sun a day. If radishes are planted in too much shade, or even where neighboring vegetable plants shade them, they will put all their energy into producing larger leaves. Till the soil (roots to do not grow well in compacted soil) and remove any rocks. If the soil is clay, mix in some organic matter to loosen and improve drainage. If you’re planting longer varieties (such as ‘White Icicle”), till to a depth of 8 inches.

When to Plant Radishes

  • For a spring planting, sow seeds 4 to 6 weeks before the last spring frost.
  • For a fall crop, sow seeds 4 to 6 weeks before the first fall frost.

 See local frost dates here.

How to Plant Radishes

  • Add organic matter before sowing but also avoid fresh manure or fertilizers high in nitrogen; overly rich soil will encourage lush foliage at the expense of radish roots.

  • Radish seeds have a fairly long shelf life. Don’t be afraid to plant radish seeds that are up to 5 years old. All may not germinate, but you’ll have plenty that will.
  • Direct-sow seeds outdoors about 1/2-inch deep and cover loosely with soil. Space 1 inch apart in rows 12 inches apart. Water seeds thoroughly, down to 6 inches deep.
  • Sow another round of seeds every 10 days or so while weather is still cool for a continuous harvest of radishes in the late spring and early summer.

Check out this video to learn how to plant radishes:

Growing

Thinning Radishes

“Thinning” is probably the most important step of growing radishes. Once the seedlings are 2 inches tall or about a week old, it’s important to thin radishes to three-inch spacings. Crowded radishes do not grow well and you’ll end up getting small, shriveled, inedible roots.

To thin, just snip the greens at the soil line. The thinnings are edible, so add to a salad! Or, if thinnings have been carefully extracted with roots, leaves, and stem intact, replant then. Transplants might be a bit stressed, but they should recover.


Photo credit: Larisa Lofitskaya/Shutterstock

Watering Radishes

  • Consistent, even moisture is key. Don’t let it dry out or you’ll get pithy, pungent roots but don’t let it get waterlogged or the roots will rot. A drip irrigation system is a great way to achieve this. 
  • Mulch the radishes with compost enriched with wood ashes to help retain moisture in dry condition as well as keep root maggots at bay.
  • Weed often; weeds will quickly crowd out radishes.
Harvesting

The biggest mistake gardeners make with spring radishes is leaving them in the ground past their maturity, they will get tough and taste starchy. Winter radishes, on the other hand, can keep in the ground for a few weeks after they mature, if the weather is cool. Finish the harvest before frost. 

  • To harvest, check your seed packet! Different types of radishes have different grow times. Some varieties are pulled as soon as 3 weeks after planting, when roots are approximately 1 inch in diameter. Pull one out as a test. 
  • Another good sign that your radish root is doing well is that the green growth above the soil is 6 to 8 inches tall. 
  • Finally, you should see or feel the “shoulder” or top part of the radish pushing up against the top soil.

If some radishes bolt before you have a chance to harvest them, leave a few to develop seedpods. The seedpods, which look like tiny bean or pea pods, are actually quite tasty in a salad.

How to Store Radishes

  • Cut off the tops and the thin root tail, wash the radishes, and dry them thoroughly. Store in produce or zip-top bags in the crisper drawer of the refrigerator.
  • Radish greens can be stored separately for up to 3 days. Put them in a separate produce bag with a dry paper towel.

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Wit and Wisdom
  • For hoarseness, swallow slowly the juice of radishes. –18th-century remedy
  • Got a mosquito bite? Apply radish juice to take away the sting and itching.

Pests/Diseases

Radish Pests and Diseases

Pest/Disease Type Symptoms Control/Prevention
Cabbage root maggots Insects

Wilted/stunted plants; off-color leaves; larvae feeding on roots

Use collars around seedling stems; monitor adults with yellow sticky traps; use row covers; destroy crop residue; till soil in fall; rotate crops

Cabbage worms Insects

Leaves have large, ragged holes or are skeletonized; heads bored; dark green excrement; yellowish eggs laid singly on leaf undersides

Handpick; use row covers; add native plants to invite beneficial insects; grow companion plants (especially thyme); spray Bacillus thuringiensis (a bacteria that affects larvae and grubs)

Clubroot Fungus

Wilted/stunted plants; yellow leaves; roots appear swollen/distorted

Destroy infected plants; solarize soil; maintain soil pH of around 7.2; disinfect tools; rotate crops

Flea beetles Insect

Numerous tiny holes in leaves

Use row covers; mulch heavily; add native plants to invite beneficial insects

White rust Fungus

Chalk-white blisters mainly on leaf undersides; small, yellow-green spots or blisters, sometimes in circular arrangement, on upper leaf surfaces; possible distortion or galls; stems may also be infected

Destroy infected plants; choose resistant varieties; weed; destroy crop residue; rotate crops

Cooking Notes

Many folks do not realize that radishes have uses well beyond the salad garnish! Radishes are great for picking with carrots or to be fermented into kimchi. The small types can be snacked on whole (with their green tops as handles), dipped into salted butter and lime. Of course, radishes can also be grated into cabbage slaws to add some flavor.

Radishes can also be cooked. You can roast halved radishes until buttery and tender. And the green tops can be sauteéd in olive oil with some garlic or even made into pesto. 

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