About Radishes (Raphanus sativus)

The genus name for this vegetable, Raphanus, comes from the Greek for “quickly appearing,” and it’s wholly appropriate. Radish seeds can germinate in as little as three days, and be ready for eating in under four weeks from planting, so they really are the speed demons of the vegetable garden. The whole plant is edible, although the leaves can be tough and bitter tasting. Most people grow radishes for the crunchy, sometimes spicy roots. Here are some other fun facts about radishes.

Radishes are members of the Brassica family, and their original wild form can still be found from western Asia to the Mediterranean region, where it grows alongside its cousins, turnip and mustard. Radishes have been cultivated in China for 3,000 years and in Europe prior to the time of the Greek empire. Certainly, by the 1500s, several named varieties were being cultivated in France and elsewhere in Europe, and some of these heirlooms remain on the market today.

Writing in the early 17th century, the physician Nicholas Culpepper didn’t seem to think much of the radish:

Garden Rhaddishes are in wantonness by the gentry eaten as a sallad, but they breed but scurvy humours in the stomach, and corrupt the blood, and then send for a physician as fast as you can; this is one cause makes the owners of such nice palates so unhealthful; yet for such as are troubled with the gravel, stone, or stoppage of urine, they are good physic, if the body be strong that takes them; you may make the juice of the roots into a syrup if you please, for that use: they purge by urine exceedingly.

In truth, radishes are high in ascorbic acid, folic acid, and potassium, as well as vitamin B6, riboflavin, magnesium, copper, and calcium.

Radishes may be round or elongated, and they come in a wide range of colours, although the interior flesh is always white. Round Black Spanish is an old heirloom variety dating back to 1548. It grows to a much larger size than the small red, pink, or white varieties, and has rough, dark brown to black skin over its roots, with a hotter flavour. The daikon (R. sativus var. longipinnatus) is a very large, elongated, white radish from Asia that grows to 35cm (14”) long. Though many people think of daikon as a Japanese radish, it originated in China. Interestingly, the Chinese word for carrot translates literally as “giant foreign radish.”

On the 23rd of December each year in Oaxaca, Mexico, the Noche de Rabanos (Night of the Radishes) marks an important point in Christmas celebrations. Locally grown giant radishes (some weighing 10 lbs!) are carved into figures of saints, conquistadors, and revolutionary heroes, as well as animals and scenes depicting the Nativity. These go on display in the zocalo, and are rated for quality. The winner of the competition gets a cash prize and local fame. The origins of this festival remain unclear, but the first radish art competition was inaugurated by the mayor of Oaxaca back in 1897.

How to Grow:

Difficulty: Easy. Radishes work well in large containers.

Timing: Radishes can be grown all season, but they’re easiest when sown March/April and again August through October. In the heat of summer, try growing some in partial shade.

Sowing: Direct sow 2cm (¾”) deep, 25 seeds per 30cm (12”) in rows spaced 20cm (8”) apart, and thin to 10-12 plants per 30cm (12”).

Soil: Moderate to heavy feeders. Best in rich, loamy soil amended with composted manure. Add 4L (1 US gallon) of complete organic fertilizer for 10 sq m (100 sq ft) of bed for background fertility. Lime beds in fall, before planting, to bring the pH to 6.0-6.8.

Growing: The real secret to growing this little vegetable is speed. Sow a short row frequently, thin them quickly, keep them watered, eat them quickly, and sow some more. Winter radishes need to stay in the ground much longer, where they will stay fresh until eating.

Harvest: Harvest promptly when radishes are the size of marbles. Leaves and developing seed pods are also tasty. Harvest seed pods while they are still green.

Storage: Radishes do not retain their crisp, appealing texture for long after harvest, so eat them fresh.

Seed info: At least 80% of seeds will germinate in optimum conditions. Usual seed life: 4 years.

Growing for seed: If growing for seed, each variety should be isolated by 1km (½ mile).

Pests & Disease: Root maggots and flea beetles can be a problem. Expect to lose 20-30% of your crop to maggots if you don’t use a floating row cover.