Raphanus sativus, var niger
Radishes are quick growing annual or biennial plants native to Asia, but can now be found worldwide. The black Spanish radish is grown for it’s swollen globular up to 10 cm in diameter tap roots. The skin colour of the root is black, but the flesh is white. The up to 60 cm long green leaves are arranged in a rosette on the centre of the root. The leaves show a big terminal lobe and several smaller lobes nearer to the root. If the radish goes to flower it shows the typical cross-shaped flower of the cabbage family with four petals. The black Spanish radish is a Winter variety of radish.
How to grow:
Sow 1.5 to 2 cm deep directly into well drained soil in spots 30 cm apart. Put in 3 seeds per spot, 2 cm apart. Choose a sunny place for Autumn and Winter and light-shade for Spring and Summer. Plants appear within a few days. Thin the plants to 2 and finally one plant per spot, 30 cm apart and mulch between the plants. Plants need to be watered consistently.
Doesn’t need much fertilising.
Harvest in about 8 weeks in warm seasons and 10 weeks in cooler seasons. Harvest as soon as the root has developed a good size, for sweeter flavour.
Growing in the neighbourhood:
Likes to grow with pea, cucumber, nasturtium and lettuce.
Pests and other problems and how we deal with them:
Caterpillars of butterflies, especially the white cabbage butterfly are pests on black Spanish radish. We keep them out by netting the bed with a 5-10 mm net as long as the plants are small. A bit of leaf loss on mature plants is tolerable, if caterpillars take away too much leaf material we spray the plants with a bacterial solution that controls them.
All members of the cabbage family can be affected by a single-celled organism deforming the roots and making it hard for the plants to take up water. The problem is called club root and requires serious soil treatment. We try to avoid this by strictly rotating crops.
All year but best in Autumn, Winter and early Spring
Radishes cross pollinate with other plants of the cabbage family. In order to collect useful seeds the mother-plant would need to be kept isolated.
How to harvest and use:
The whole plant is harvested. Radishes need to be harvested timely, so the flesh is crisp and sweet, it becomes bitter and tough if left in the ground too long. The bulb of the radish is kept to be eaten, the leaves and the small roots at the bottom are taken to the compost.
Every part of the Black Spanish radish can be eaten. If not peeled the slices have an attractive thin black round. If grated it is best peeled. It is usually eaten raw as part of a salad but can also be steamed. The raw flesh has a crisp texture and a peppery flavour.