From Real Seeds, this huge cooking radish grows to almost tennis-ball size. It is incredibly easy to grow. This variety has amazing black skin which protects it from cold and pests. Peel the skin before cooking.
Sow thinly in well prepared soil from mid July onwards. Thin to 7-8cm apart, then later as they grow bigger thin again to 15-20cm apart, using the thinnings to cook with. Water in dry weather. Pull them all autumn and winter as needed, they will withstand a lot of cold, but you might want to lift and store some in a cool garage or shed in case of extreme freezes.