Longipinnatus' is an upright annual or biennial with ovate, irregularly-lobed, mid- to bright green leaves, insignificant white flowers and a long, cylindrical, edible, white taproot.
With summer varieties little or no thinning is required. Thin other varieties out until the seedlings to 3-5cm (1-2in) apart. Harvest as soon as the roots reach reasonable size, if left too long they will become woody.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: neutral and basic (alkaline) soils.
The Japanese radishes have higher concentrations of glucosinolate, a substance that acts against the thyroid gland. It is probably best to remove the skin