Once, for me, radishes were an afterthought. I'd plant a patch in spring for salads, but forget it as spring greens and early peas began to produce. However, last year I tried some different radishes. These weren't the small, round red salad-bar type, but a selection of varieties from a large group, mostly from Asia.
The roots of these radishes can vary from 18-inch-long white cylinders to 6-inch-diameter tricolor balls of red, green, and white. They're bigger, crunchier, and often more mildly flavored than common radishes. These roots are a staple in Asia, where they're eaten in salads, soups, stir-fries, and sauces. Oriental radishes can be grown from spring to fall in most parts of the country, depending on the variety.
The white daikon ("big root" in Japanese) is common in Japan, and gardeners in increasing numbers are growing it here. The daikon has a milder, sweeter flavor than ordinary radishes. The root shape of all varieties is either long and cylindrical or short and round. The cylindrical roots range from 6 inches to 2 feet long and are either tapered or blunt at the end. The round varieties are the size of a baseball. Japanese breeders have developed varieties that mature at different times of the year, so to get the best roots for your growing area, choose varieties carefully.
The time to plant daikon is late summer, when soil temperatures are above 60° F, so they mature in fall. If planted in spring, these varieties bolt without forming roots. Some of the best fall daikon varieties are 'Miyashige', an open-pollinated variety that produces foot-long, stump-rooted cylinders, and 'Summer Cross #3', a heat- and disease-tolerant hybrid with tapered roots.
You don't have to wait until summer to plant, however. Newer hybrids such as 'April Cross', 'Omny', 'Spring Light', and 'Spring Song' also mature in 50 to 60 days, produce more uniform roots,and resist bolting better than fall types do. Radish enthusiasts can plant them in spring or summer.
Spring-planted daikon grow best if sown under a floating row cover as soon as you can work the ground. For a constant harvest, plant small rows every month from spring to late summer. If you garden in hard clay, turnip-shaped types such as 'Shogoin' grow best because three-quarters of their root grows aboveground.
From China hail red, green, and white fleshed radishes. The green and red fleshed varieties are highly prized for their taste and good looks. One red-fleshed type, Beauty Heart, has been grown for thousands of years. Carving these beautiful, round, red-fleshed radishes into rosettes to decorate dinner tables has become a Chinese art form.
Red-fleshed radishes grow best when planted in late summer to mature in fall. They have denser flesh than the Japanese types have but are just as sweet. Over the years, breeders have developed varieties with more uniform shape and better color, which are easier to grow than the original Beauty Heart. Some of the best are 'Mantanghong', 'Misato Rose', 'Red Meat', and 'Tricolor'. They form 2- to 4-inch-diameter spherical roots in 50 to 60 days.
The green-fleshed Chinese radishes are rarer, but less finicky about planting times than the red-fleshed types. 'Korean Green' and 'Misato Green' form 8- to 10-inch cylindrical roots with green skin and flesh that mature in 55 to 60 days. The skin retains the pungent radish flavor, but the flesh is sweet. Green-fleshed radishes are more cold-tolerant than the red-fleshed types and can be planted in spring or summer. The intensity of green coloring varies with the variety and is deepest at the root's top.
'China Rose' and 'Cherokee' are two examples of white-fleshed, red-skinned varieties. Like the green-fleshed varieties, they can be planted in spring or summer to mature their 6-inch oblong roots in 60 days.
Not all unusual radishes are from Asia. The Black Spanish variety has growth habits that are similar to those of Chinese radishes. It produces either round, turnip-sized roots or cylindrical carrot-sized ones. The skin is rough and black, but the dense flesh is white with a zesty flavor. Growers plant 'Long Black Spanish' and 'Round Black Spanish', the two most widely available kinds, in summer for a fall harvest.
'Nero Tondo', a newer selection, is more cold-tolerant than some black radishes, can be planted in spring or summer, and has a crisp texture. One of the trademarks of black Spanish radishes is their ability to keep well in a root cellar for 4 to 6 months through the winter, adding zip to winter soups, salads, and stews.
For an unusual taste experience, try radish seedpods. When exposed to cool temperatures in spring, any red-fleshed Chinese radish, black radish, or fall daikon will prematurely bolt and form seedpods. Some kinds of daikon are even grown especially for their high-quality pods. For example, 'Munchen Bier' and 'Rattail' produce tasty 2- to 3-inch pods. Furthermore, when 'Munchen Bier' is planted in late summer, it produces a highly prized fall daikon root that Germans dip in salt and serve with a glass of beer. Spring-planted 'Munchen Bier' produces tangy, green-to-purple seedpods in 50 days; these pods are great in stir-fried dishes.
The key to success with these mild-flavored exotic radishes is planting the right variety at the right time, maintaining soil fertility, and keeping plants as stress-free as possible with regular watering and fertilizers. Generally, cool temperatures while roots are maturing produce mild-flavored radishes.
Grow these kinds as you would any other radish. Prepare the seedbed well, digging a 1-inch layer of compost into the soil, and remove any rocks and debris that could inhibit root growth. Generally, radishes grow best in raised beds, where the soil warms faster in spring, water drains more quickly, and root diseases are less likely to develop than in nonraised beds.
Broadcast the seed, then thin seedlings to 4 to 6 inches apart once four true leaves appear. Keep the bed well watered, and scout for pests. The two major insect problems are flea beetles and root maggots. You can control both pests by placing floating row covers over the plot.
Don't be alarmed when the roots grow on top of the ground instead of underground. Most Oriental radishes grow one-third of their root aboveground (the green part that results on white ones is safe to eat). If you can't eat all your radishes right away, refrigerate them for up to a month.
Now, radishes are anything but afterthoughts in my garden. I enjoy them well into the fall.
Charlie Nardozzi is a senior horticulturist at National Gardening.