Fun facts about radishes

Radishes are thought to have been first cultivated in China, spreading into Europe in the 1500s and the Americas shortly thereafter.

The pungent, peppery flavor of radishes (as well as other members of the Brassicaceae family such as horseradish and wasabi) is caused by allyl isothiocyanates. This chemical does not exist in an undamaged radish root but is formed when two other chemicals (glucosinolates and the enzyme myrosinase) are liberated as the root is cut or chewed.

Different radish varieties have different levels of spiciness. Black Spanish is known to be the hottest and French Breakfast is known to be one of the mildest. Other factors that have been said to contribute to an increased spiciness are large size, slow growth, growth in hot weather and lack of water. Scientific evidence for these claims, however, is not readily available.

The annual Noche de Rábanos (or “Night of the Radishes”) Festival is held on Dec. 23 in Oaxaca, Mexico. This celebration that began in the late 1800s features nativity and other scenes carved from large radishes.

Need a rapid reward for your gardening efforts? Plant radishes for a quick and easy harvest that livens up foods with its spiciness and crunch.

The radish is a root vegetable in the Brassicaceae family (which includes kale, broccoli and cabbage). Its scientific name (Raphanus sativus) derives from the Greek meaning “quickly appearing,” a most appropriate label. Some radish varieties can go from seed to a harvestable root in less than a month.

Depending on the variety, radishes range in shape from spherical to cylindrical or tapered. The outside skin can be white, yellow, pink, red, purple or black. The radish flesh is usually white. Exceptions include the watermelon radish, a large Chinese cultivar that resembles a seedless watermelon due to its pink to magenta flesh, and the purple daikon radish, a Japanese variety with a starburst of purple “tie-dye” inside.

Radishes are easy to grow. Plant them in full sun for best results. Avoid planting them in overly rich soils that encourage lush foliage at the expense of the roots or where members of the cabbage family recently were grown.

Plant radish seeds ¼ to ½ -inch deep. Although the seeds are small, try to space them at least an inch apart to provide plenty of room to grow. After the radishes sprout, thin them so they are at least 2 inches apart. Larger varieties need more space, so check the seed packet for thinning instructions.

Keep the soil uniformly moist but not too wet as the seedlings grow. Radishes need little in the way of fertilizer.

Radishes mature quickly, so check your planting frequently. As the radishes grow, you will be able to see the tops of their roots peeking above the soil from which you can estimate their size. When the roots reach the size expected for the variety, harvest them, whether you plan to use them immediately or not. Unlike many root vegetables, radishes cannot be left in the ground because they will crack and become tough, if not harvested quickly.

Radishes can be stored in a plastic bag in the refrigerator for two to three weeks. Cutting off the green tops or adding a wet paper towel to the bag will help keep the roots crisp by retaining moisture.

Radishes have a spicy flavor and a crunchy texture, making them a popular addition to salads and vegetable trays. The leaves can be used in soups, as cooked greens and in pesto. The roots can be sliced into stir-fries, grated into slaw or diced into egg and potato salads.

Radishes love cool weather. Plant spring varieties (such as ‘Cherry Belle’ and ‘French Breakfast’ as soon as the ground can be worked (March or April). Make small weekly sowings (instead of one large sowing) so that you are not overwhelmed with too many radishes at one time.

When the weather reaches an average of 65 degrees or warmer, stop sowing radishes because the plants will not form a substantial root but will go to seed.

Resume planting radishes in mid-July and early August, planting spring varieties for a fall harvest and overwintering varieties for harvest the following spring. Recommended winter varieties include ‘All Season’ (Daikon), ‘China Rose,’ ‘Dragon’ and ‘Runder Schwarzer Winter.’

Jeanette Stehr-Green is a WSU -certified Clallam County Master Gardener.