Fall for Radishes

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Photo by Adobe Stock/mythja

Juicy, spicy radishes are a quintessential spring crop, and a perfect addition to crisp, fresh salads of choice baby greens straight from soil. Most radishes don’t tolerate heat and require soil temperatures cooler than 75 degrees Fahrenheit for good germination rates. For this reason, radishes take a growing hiatus during the summer. Despite these restrictions, an additional radish crop can be grown during the cooler months of autumn. What a wonderful way to finish your growing season! Try these tips for a bountiful fall radish crop.


Radishes (Raphanus sativus) have a long history of cultivation. They’re documented as food crops in Egypt as early as 2000 B.C., and they were grown in China by 500 B.C. Radishes arrived in Europe in the mid-16th century, possibly via the Mediterranean. Centuries of breeding have given us a surfeit of choices when it comes to flavor, size, color, and shape. Nowadays, you’ll find beautiful red, pink, white, green, yellow, and black radishes, in perfectly round or long cylindrical shapes.

Quick, Yet Bountiful

For fall radishes, select a cultivar that grows quickly. Check the number of days until maturity on the seed package. As fall radishes are usually sown 4 to 10 weeks before the first frost, whatever cultivar you choose will need to grow to a harvestable size in that time. (The first frost has the potential to be a surprise, of course, but for a “best guess,” check your region’s frost-free period and work within that range.) As a guideline, plant seeds from August to early September in most areas. Direct sowing is preferable for radishes, as they don’t transplant well.

When you sow your radishes in fall, your vegetable garden might already be prepared for the coming growing season. If that’s the case, seed radishes wherever you have room; there’s no need for straight rows. If possible, plant the seeds in blocks to give them the best chance to succeed. Remember not to crowd radish plants too closely together. While they’re diminutive plants, good root development relies on proper spacing. For most cultivars, at least 2 inches is sufficient.

Photo by Adobe Stock/photopixel

If you’re freshly preparing a new garden bed (or a section of it) for a fall radish crop, ensure the soil is amended with a 1-inch layer of well-aged compost. Bear in mind that adding nitrogen fertilizer or nitrogen-rich compost can cause the roots to fork, an undesirable trait in radishes. It can also cause too much leafy growth and too little root development. In the years after planting, amend the bed with compost in spring or autumn, whichever is more convenient. The soil should be well drained; plant health may be compromised by boggy soils.

Heavy, compacted soils aren’t recommended for optimum growth. Although radish roots can break through heavy soils, they may have a hard time growing to a favorable size and shape. In addition to providing nutrients, applications of compost help amend soil texture (a boon if your soil has a high clay content).

Favorable radish root development depends on good cultivation practices. Radishes will take on a woody texture and a distasteful hot flavor if the plants aren’t watered consistently and evenly. At the other extreme, too much water can encourage issues, such as rot. If your soil is sandy, it’ll be necessary to step up the frequency of supplemental irrigation. Make sure to keep up with the weeding! Radishes — like most other crops — don’t like to compete for space, light, water, and nutrients.

Besieged Brassicaceae 

Like other members of the Brassicaceae family, radishes may be targets of flea beetles. These tiny black or brown insects are instantly recognizable, as they leap from plant to plant like fleas. Since flea beetles usually complete their life cycle by late summer, they aren’t likely to be problems for fall radishes. They may, however, occasionally produce more than one generation per growing season. Larvae feed on the roots of seedlings, but don’t usually do permanent damage. The adults chew on the leaves of plants and create unsightly holes. Heavy infestations can destroy young plants. Use floating row covers to protect young radish plants from beetles. Sticky traps may also work to draw the beetles away from the plants.

Most vegetables are susceptible to aphids — a type of sap-sucking insect that reproduces like crazy — and radishes are no exception. There are many species of aphids. Several generations of offspring can hatch every growing season. While encouraging beneficial predator insects to your garden, such as ladybug beetles, is a great way to deal with an aphid problem, you may need to lend a helping hand. Using an old pair of gloves, or a soft, damp cloth, gently wipe the stems and leaves of the plants to remove the aphids, then drop them into a bucket of soapy water. Aphids may also be dislodged using a strong blast of water from the garden hose.

Root maggots are another common pest of radish plants and other members of the Brassicaceae family, such as cabbage, broccoli, and arugula. But since their life cycle is usually completed in midsummer, they don’t often affect fall-planted radishes.

The Fall Lineup

Depending on the cultivar, fall-planted radishes are usually ready about five weeks after planting. (Some may take as little as three weeks, or as long as eight or nine.) No matter what time of year you grow them, it’s always best to harvest radishes as soon as they’re ready. Leaving them in the ground never improves their flavor or texture, and it occasionally leads to cracked roots. Some excellent radish selections for fall planting are included below.

‘Shunkyo Semi-Long’: This cylindrical-shaped Asian radish is bright-red, with white flesh. Roots typically reach a length of 5 inches. ‘Shunkyo Semi-Long’ reaches maturity in about 32 days.

Courtesy Johnny’s Selected Seeds

‘French Breakfast’: This well-known French heirloom has a mild flavor and 3-inch-long red-and-white cylindrical roots. Plants take only 25 days from germination to harvest.

Photo by Baker Creek Heirloom Seeds

‘De 18 Jours’: This red, cylindrical radish is a rapid grower. It matures in approximately 18 days.

Photo by Baker Creek Heirloom Seeds

‘Early Scarlet Globe’: This is a German cultivar that first appeared in the United States in 1885. It’s harvestable in about 20 days.

Photo by Baker Creek Heirloom Seeds

‘Red Bartender’: This slender, dark-pink radish can reach a length of up to 9 inches. It’s ready to eat in approximately 35 days.

Photo by Baker Creek Heirloom Seeds

‘Crimson Giant’: This large (1-1⁄2 inches in diameter), round, red radish is harvestable in about 29 days.

Photo by Baker Creek Heirloom Seeds

Cold-Weather Cultivars

What on earth are winter radishes, and how do they differ from those planted in the spring or fall? Winter radishes usually take longer to reach maturity. They’re planted in mid-to-late summer and harvested in autumn. (Some of the quicker-growing cultivars may also be planted as fall crops.)

Winter radishes typically don’t have globe-shaped roots. Their roots tend to be long and cylindrical, and in the case of some daikon radishes, very large. Unlike other radishes, they store well. After harvesting, remove the soil from the roots and cut the greens off. Store the roots in a single layer of damp (not soaked) sand or sawdust shavings in a box. Place them in a pantry or cold storage for up to four months. Check them regularly and discard any that are moldy. Below are some delicious winter radish cultivars to try.

‘Round Black Spanish’: This beautiful globe-shaped black radish with pure-white flesh is of Spanish origin, and dates back to the 16th century. ‘Round Black Spanish’ will mature in about 60 days.

Photo by Baker Creek Heirloom Seeds

‘Chinese Red Meat’: When cut, these pretty Asian radishes look like miniature watermelons, with pink flesh and a light-green rind. They’re harvestable in about 50 days.

Photo by Baker Creek Heirloom Seeds

‘Sichuan Red Beauty’: Completely red inside and out, this radish makes a statement in pickles and fresh salads. It should mature in approximately 50 days.

Photo by Baker Creek Heirloom Seeds

‘Japanese Minowase Daikon’: These thick, white radishes can reach lengths of up to 24 inches, and 3 inches in diameter. They mature in 50 days.

Photo by Baker Creek Heirloom Seeds

‘Miyashige’: This is an attractive white radish. The tops of the 18-inch-long roots are pale-green. They’re ready in 50 days.

Photo by Baker Creek Heirloom Seeds

Timely Tips

Don’t forget: You can eat all of the parts of a radish plant. The greens, roots, flowers, and seeds are all edible. If you plan to store radishes in the refrigerator, cut the greens away from the roots and bag them separately. (This will ensure the greens don’t wilt right away.) For best results, eat the plants within three days of harvest. Don’t freeze them, as they will turn mushy when thawed.

Winter radishes keep up to 14 days in the refrigerator. Pickled radishes are another delicious storage option. Shelf-stable pickles will keep in the pantry for up to six months. Refrigerator pickles will remain useable for up to one month. See “Refrigerator Radish Quick Pickles” to try them for yourself!

Seed Sources

Sheryl Normandeau is a Master Gardener and writer from Calgary, Alberta. She grows mostly vegetables, but also plants perennial flowers, and always has a few projects in the works. Read more about her pursuits on her blog, Flowery Prose.

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