Growing the Perfect Radish

Anybody can grow radishes. Even a kid can do it. But growing a good radish? Now that takes a little work and a lot of attention. And really, isn’t that exactly the kind of lesson you want to pass on to your little ones when it comes to gardening?

Radishes, a cool-weather crop, can be planted early, as soon as the soil can be worked and weeks before the last frost. In our household, they’re the first scratch on the itch to garden. Let’s go to the center of the country to gauge when you can sow radish seed. The Iowa State University Extension Service’s radish page says they can be planted in late March in the southern part of the state, in mid-April in the state’s northern counties. This suggests that they can be planted early, say February, further south. And in higher elevations and along the northern tier, try putting in radishes as soon as the snow is out and the soil is half-way friable.

Radishes come in two types, the classic and quick-growing salad types like cherry belle and French breakfast, and winter, storage types that grow larger over an entire season and can be kept for weeks after harvest. Though the classic red radish is one of the most attractive root vegetables, radishes, often heirlooms, come in white, purple and even yellow.

Peppery or spicy, heirloom radish is a favorite salad addition. Some are quick yielding, ready in a month or so. Larger types, like China Rose, need longer growing periods but are also good for fall storage.

Depending on the conditions, radish seed will germinate, even in cool soils, within a week or so. These relatively quick results are perfect for kids and we adults who have a child’s attention span. The Oregon State University Extension recommends radishes as a confidence builder, something to plant that will grant you easy success. A sowing every couple of weeks will give you radishes well into the summer season while covering for any plantings that were too early and didn’t receive cooperation in the form of abundant sunshine and lack of late, heavy frosts, from Mother Nature.

Getting the seed to germinate is the easy part. Growing tasty, crunchy radishes can be difficult. How many times have we planted radishes only to have the roots turn woody and flavorless, or to end up with no roots at all? The key, as your children will learn, has to do with providing and maintaining the proper growing conditions.

Ending up with only tops and no roots at all is a common problem. Proper soil preparation is most often the reason one’s radishes don’t grow round, edible roots. You want your soil well-worked down to a foot or more even if the radishes you grow are only an inch across. Radishes thrive on the moisture that’s brought in through the tap root that extends beyond the root bulb. You can make your soil radish-friendly by working in plenty of finished compost and by adding a little sand for drainage and friability. It’s also important to plant radish seed deeply enough, say a half-inch, and not right on the surface.

The other thing that encourages radishes to grow all tops and prevents them from developing root bulbs is not having enough sunlight. Make sure your radishes are planted in full sun. Most guides recommend at least six hours. We’d suggest more is better. If you have a cloudy spring, then your radishes may not root nicely. Wait until more sunshine is in the forecast and plant them again.

Another thing that encourages top growth and discourages roots is too much nitrogen. Using compost as a soil amendment will not only guarantee the right soil texture for rooting but will also help keep nitrogen in balance. Radishes like phosphorous so if you intend to put down fertilizer before sowing, use one that is higher in “P” than “N,” in the “N-P-K” ratio, like bone meal.

Once you’ve provided the right growing conditions for your radishes, the main thing that results in tasty, crispy radishes is speed. Growth should be consistent. Once planted, water your newly sown seed to a depth of six inches or so, then keep it moist. Allowing the soil to dry out completely will result in woody bulbs. This is the perfect way to involve you kids between planting and harvest. Get them to test the soil moisture regularly. The old finger test is kid-perfect. When they wiggle their finger into the soil and find it close to dry its time to water.

Of course, kids love to water and your youngest gardeners may decide that more moisture is needed whether it’s needed or not. Luckily, radishes will adapt to this kind of treatment, especially if you’ve prepared the soil well. A little supervision during the first soil tests and waterings will go a long way. If your kids insist on way too much water? Well, actions have consequences.

When to harvest? Small, salad-type radishes of the kind we’re talking about here will be ready when the bulbs are an inch across and slightly poking through the soil, somewhere between four and six weeks. Allow them to get too large or stay in the ground too long and they’ll lose their flavor and get tough. Wash them clean and slice them for salads or eating by themselves. The good news is that radishes are high in B vitamins and certain minerals. That peppery taste can become attractive to kids. I remember being dared by my grandfather to take bites out of whole radishes. Now what kid will pass up a dare like that?