Organically grown seeds. This tasty vegetable forms an overground tuber; a true delicacy both cooked (tastes like cauliflower) and raw (tastes like celery). Sow in a greenhouse in soil blocks of 5 cm, then transplant later in greenhouse or garden. Give plenty of compost and water in order to prevent the tuber from becoming too fibrous. Harvest on time. Keeps fairly long in a cool place. Use anti-insect nets to protect young plants against cabbage midge.