Black radish

The domestication and early history of radishes is not completely solved. Black radish likely originated from Raphanus maritimus while spring radish varieties originated from Raphanus landra.[2] Cultivation can be traced back to Ancient Egypt, where illustrations in tombs show extensive use of a long variety of radish.[3] The region of today's Syria is likely the geographical origin of black radish.[2] It was first mentioned in Europe in 1548.[4] At that time, it was one of the most common radish varieties. It lost its importance with the introduction of new radish-varieties but was still widely cultivated until the early 20th century.[2] In the second half of the 20th century it had to give way to spring radish varieties and got "forgotten" in European cuisine.[5] It is now considered an “old variety” and enjoys renewed popularity as health-food through mentions in lifestyle and food blogs and magazines.[6][7]

Black radish, long variety

Black radish is an annual plant whose root is encased in a black or dull brown skin and with a white flesh.[8] Generally, black radish is bigger than spring radish varieties and grows around seven to ten centimeters in diameter or length. The plants can grow up to a height of 0.5 m (20 in).[9] Depending on the variety, the radishes are round, cylindrical or elongated.[10]

Cultivation

Black radish takes 35 days to 55 days or longer to mature.[11] It can be sown in mid summer to autumn, depending on the climate and be harvested in autumn or winter.[11][12] Too high temperatures during growth should be avoided because the radishes get woody and spongy at such a climate.[13] Sowing can happen directly in the field or indoors and the plants can later be transferred to the field. The plants should be spaced 5–10 cm (2–4 in) to each other or even more, if bigger radishes are desired. The seeds should be sown in a depth of 0.6–1.2 cm (¹⁄₄–¹⁄₂ in).[11] Black radish requires a well-drained, loamy, soil with a pH of 5.9 to 6.8. The plants should get around six to eight hours of sun.[14] Harvest should take place once the top portion is poking above the soil.[14] Known pests are cabbage root maggots, cutworms and flea beetles.[13]

For storage the mature plants can be kept in the ground if temperatures are low.[13] The radish can also be kept for months in a root cellar[11] or be stored in the fridge for up to three weeks at 0–5 °C (32–41 °F).[14]