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Radish Growing and Harvest Information

by chuck.mcmullan
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Radishes are a fast-growing, cool-season crop that can be harvested in as little as twenty days. There are well over 200 varieties: including French radishes, daikon radishes, and other specialty varieties in a surprising array of colors, including white, purple, black, and even green. Eaten raw they can be whole, sliced, diced, or grated. You can also cook and pickle them. Most of them are typically eaten fresh and make a good addition to a salad or a substitute to pepper on a sandwich.

Where to Grow Radishes

Radishes require a spot with full sun, fertile soil, and good drainage. Some varieties can be grown in partial shade. They will thrive in cool, moist soil. In cooler climates, they can be planted in both the spring and fall. In warmer climates, they should be grown over winter.

Recommended Radish Varieties

  • Cherry Belle is the classic radish. Their roots are bright red, mildly pungent, and mature somewhere between 1/4 -1 inch in diameter. Cherry Belle is one of the few varieties that can be grown in the shade and matures in about 24 days.
  • White Icicle radishes have a mildly hot flavor. They are white and about 6 inches long, maturing in about 20 days. This variety of radish requires well-cultivated soil as it has deeper roots than other varieties.
  • French Breakfast is red with a white tip and a similar shape to the White Icicle. It has excellent flavor, withstands early summer heat, and is ready for harvest in about 24 days.
  • Champion radishes are bright red with a crisp white flesh. They do best in cool weather and are a good choice for early or late season planting. They are ready to harvest in about 28 days.
  • Easter Egg is a multicolored mix of red, purple, and white round radishes, these are a surprise every time you harvest them.
  • Miyashige has long white roots and is the classic Asian daikon radish. Sow in late summer for a fall harvest.  Miyashige stores and pickles well.

Soil for Radishes

Radishes are not very particular about soil type but will do best with rich, well-drained soil with a pH of about 6.5. Till the soil 6-10” deep, removing all rocks and mix in good compost. If your soil is clay, you may want to add some compost and sand to loosen it up a little. As most plants, they would prefer a healthy addition of compost worked into the soil at planting time to provide some good organic matter to the soil. Radishes do nicely where leaves have been worked into the soil the previous fall.

Temperature
Germination45 - 85 F
For growth60 - 65 F
Soil and Water
FertilizerNot required.
Side-dressingNot required.
pH6.0 - 7.0
WaterEven and moderate to heavy.
Measurements
Seed Planting Depth1/2"
Root Depth3 - 6"
Height2 - 6"
Width2 - 6"
Space between plants
In Beds2"
In Rows1" (small)
2" (large) - thin to 4 - 6" eventually
Space Between Rows8 - 12"
Average plants per person10 - 20
Harvest
Harvest radishes once the root has become plump. Harvest the whole crop at once.
First Seed Starting Date: 21 days before last frost date
Last Seed Starting Date: 45 Days before first frost date
Companions
CompanionsBeets, carrots, spinach, parsnips, cucumbers, beans, lettuce
IncompatiblesCabbage, cauliflower, Brussels Sprouts, broccoli, kohlrabi, turnips

Planting Radishes

Radishes are particularly sensitive to any interruptions to their growth and consequently are best direct-seeded outdoors. They are sensitive to frost, but if required, they can be sown indoors about 2 weeks prior to the first frost. If sown indoors, use a biodegradable pot so that you can plant the whole pot when it comes time to transplant them outdoors to minimize disruptions to their root system. Whether you plant indoors or out, the most important thing is to keep the soil moist. Sow seeds about 1/2“ deep and about an inch apart, with 8-12” between rows, depending on how large your variety is. Once the radishes begin to grow, you can thin them to about every 2”.

Radishes can be sown wherever there is an empty space, from early spring until early summer, and starting again in the early fall. They make useful “row markers” sown among slow germinating plants like carrots and parsnips. By the time the carrots or parsnips have germinated, it is close to the time to harvest the radishes. Since they germinate in a few days, it makes weeding between the rows much easier.

Daikon Radish

Cultivating Radishes

Keep your rows of radishes weed-free and give them a heavy watering every three days to ensure proper root development.

Harvesting Radishes

Radishes are at their best for a very short time. If they are left in the ground too long, they will develop a sharp taste and a pithy texture, and their roots will eventually split. Radishes are ready to harvest in as little as 20 days, depending on the variety. Once the root has become plump, they are ready to pick. Harvest the whole crop once it matures, and store them in the refrigerator. If harvesting in hot weather, pull radishes from the soil and drop them into a bucket of cold water. Remove greens and refrigerate for up to 3 weeks. Storage can be extended up to several months in a properly maintained root cellar.

Storage Requirements
Remove green tops and store in plastic bags or containers with some water inside the refrigerator.
Fresh
TemperatureHumidityStorage Life
32F95 - 98%2 - 4 weeks
Preserved
MethodTasteShelf Life
CannedGood12+ months
FrozenPoorPoor
DriedPoorPoor

Radish Pests

  • Fleas Beetles will leave small holes in radish leaves and do seem to have a preference for radishes. Your radishes will likely do just fine even if the leaves have a few holes in them.
  • Root Maggots will leave holes or channels in the radish skins.

A lightweight, floating row cover applied at the time the seeds go into the ground will keep flea beetles away, and also prevent root maggots from spoiling the roots.

Radish Diseases

None of major concern.

Radishes as a trap crop

Insects tend to have preferences, much like humans when it comes to what they eat. They may eat one garden plant when it is the only thing available, but if given the choice, they might choose something they like better. These preferred plants are often within the same plant family. The same root maggots that like broccoli roots, also like radish roots. Flea beetles like broccoli and cabbage seedlings, but also like kale, turnips, pak choi, and radishes. That’s the idea behind a trap crop. You could, for instance, plant radishes with the primary intent that they would attract the root maggots and flea beetles and leave your broccoli and cabbage alone. Many gardeners have found radish to be a good trap crop to protect many of the cabbage family plants.

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