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

How to Grow Radishes: The Complete Guide

a bunch of red radishes with greens in a bunch
Photo Credit
Annette McCarthy
Botanical Name
Raphanus sativus
Plant Type
Sun Exposure
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Planting, Growing, and Harvesting Radishes

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Radishes are planted in the cool temperatures of spring and autumn, and this hardy root vegetable is ready to harvest in mere weeks. Learn how easy it is to grow radishes.

Speedy radishes can be grown almost anywhere: between larger vegetables, around soon-to-finish crops, in pots, or to give peppery roots both early or late in the season. Try some for yourself, including delicious winter radishes to sow from late summer. In this short video, we’ll tell you all you need to grow them successfully.

What’s the most opportunistic crop you could possibly grow? For me, it’s the humble, lowly radish—or rather, the rousing, ravishing radish! Squeeze a sneaky row or two between larger vegetables. Sow them around crops that are about to finish. Grow them in pots, or squeeze in an extravagantly early or late harvest of these peppery roots. They’re super fast, super flexible—oh, and super yummy! So let’s crack on and sow some!

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 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.

a bunch of radishes

Planting

Because of their size and speed, radishes may be grown just about anywhere. But ready to enjoy in as little as four weeks and taking up minimal space, perhaps their best use is as a fill-in crop, either between or within rows of slow-to-germinate vegetables such as parsnip, or as a quick, in-and-out crop right at the start or end of the growing season.

Radishes prefer full sun but grow well in partial shade, too, and in hot climates, will prefer full shade in the height of summer. 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. 

Keep the soil moist, and you’ll be rewarded with clusters of mildly peppery roots in next to no time.

Till the soil (roots 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.

Sowing Radishes Early in Plug Trays

Begin sowing under cover from late winter, either directly into containers of potting soil, into greenhouse borders, or into plug trays of general-purpose potting mix.

Fill plug trays with potting mix, firm down, then sow a pinch of three to five seeds per module. Cover with a little more of the potting mix, then water. If it’s especially cold, you’ll need to germinate them indoors and then move them back into a greenhouse or cold frame as soon as the seedlings appear. After a couple of weeks of sheltered growth, and once the seedlings have filled out their modules, they’ll be ready to plant out under row covers or hoop houses.

Plant into soil earlier enriched with well-rotted compost or manure and raked to a fine tilth. Remove the clusters of seedlings from their modules, then dibber a hole for each plug. Drop in the plug and firm it into position so each cluster’s about 6in or 15cm apart in both directions. Cover the seedlings with row cover or horticultural fleece, properly held down at the edges, until the weather warms up.

How to Plant Radishes

Of course, sowing radishes directly where they are to grow is the easiest way to start them off. As cool-season crops, some radishes can germinate at temperatures as low as 41 Fahrenheit or five degrees Celsius. Sow from very early spring, initially under row covers or hoop houses, spacing rows about 8in or 20cm apart. Sow thinly along the row—ideally, so seeds end up spaced around half an inch or one centimeter apart. Water if it’s dry, and then, about a week after germination, thin the seedlings to leave them an inch or 2cm apart within the row.

  • 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 the weather is still cool for a continuous harvest of radishes in the late spring and early summer.

Grow Some Radishes for Winter

Many hardy radishes can be sown towards the end of summer to give an autumn or early winter harvest of roots. Sowing regular red, round or white-tipped radishes into containers is a great way to extend the season—by simply bringing pots under cover when the weather turns cold.

Another option is to grow bigger winter or Asian varieties of radish, which naturally prefer cooler temperatures. The most popular is the daikon or Japanese mooli radish. Look out for Chinese and Korean varieties, too—all with a mild flavor ideal for salads but also great in soups and stews. Then there’s the stunning watermelon radish or the chunky, spicy Spanish Black radish, whose peppery tang holds up well in stir-fries.

Winter radishes are leafier than their summer cousins. The spicy leaves may be used like spinach, wilted into hot dishes, or even whizzed up in a pesto.

Sow winter radishes a little further apart, so rows are at least a foot or 30cm distant, then thin the seedlings to leave at least a couple of inches or 5cm between each plant.

Check out this video to learn how to plant radishes:

Growing

Thinning Radishes

“Thinning” is probably the most important step in 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 them to a salad! Or, if thinnings have been carefully extracted with roots, leaves, and stem intact, replant them. 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 conditions 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; then, they will get tough and taste starchy. Winter radishes, on the other hand, can be kept 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 growth 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. 
  • Harvest roots as soon as they have reached their final size. Don’t delay, as they can go from crisp and crunchy to woody and excessively spicy within a matter of days. Lift the biggest roots each time you harvest, so the remainder can continue to swell.
  • 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 topsoil.

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.

radish-pile_full_width.jpg

Gardening Products
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/DiseaseTypeSymptomsControl/Prevention
Cabbage root maggotsInsectsWilted/stunted plants; off-color leaves; larvae feeding on rootsUse collars around seedling stems; monitor adults with yellow sticky traps; use row covers; destroy crop residue; till soil in fall; rotate crops
Cabbage wormsInsectsLeaves have large, ragged holes or are skeletonized; heads bored; dark green excrement; yellowish eggs laid singly on leaf undersidesHandpick; 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)
ClubrootFungusWilted/stunted plants; yellow leaves; roots appear swollen/distortedDestroy infected plants; solarize soil; maintain soil pH of around 7.2; disinfect tools; rotate crops
Flea beetlesInsectNumerous tiny holes in leavesUse row covers; mulch heavily; add native plants to invite beneficial insects
White rustFungusChalk-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 infectedDestroy 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 pickling with carrots or to be fermented into kimchi. The small types can be snacked on whole (with their green tops as handles), or 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. 

About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann

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