Radish

Light and exposure

In spring and autumn the radish likes full sun, which makes it grow fast and gives it crunch. Keep a well-exposed spot for the March-to-May sowings and the late-summer ones.

In high summer it is the opposite. Heat and full sun make it bolt and turn it hot and hollow. A spot in partial shade, or the light shade of a taller vegetable, suits it better from June to August.

Watering

Water is the key to a good radish. Regular watering, without swings, gives tender, juicy, mild roots. The soil must never dry out completely during the crop’s short life.

A lack of water or a crop that drags on makes the radish hollow, fibrous and strong in heat. In dry weather, water every day at the end of the day. A sowing well watered and without interruption is ready in a month, that is the whole secret.

Soil and repotting

The radish thrives in a light, loose, cool soil, neither too rich nor too stony. A soil too heavily manured favours the foliage at the expense of the root. A simple pass with the hand fork and a fine raking before sowing are enough.

In heavy or stony ground of the kind you meet around here, the roots deform and fork. A little well-rotted compost and some sand to lighten it clearly improve the shape and the regularity of the radishes.

Temperature and humidity

The radish is hardy and stands the cool far better than the heat. It germinates as soon as the soil reaches 5 to 8 degrees and tolerates light frosts, which allows very early sowings under our climate.

In Belgium, direct sowing is possible from March under a cold frame, a tunnel or a simple fleece that warms the soil and protects from the last frosts. In open ground with no cover, wait rather for late March or April. Conversely, as soon as the days lastingly exceed 25 degrees in summer, the radish bolts, so you then have to sow it in partial shade or take a break until late August.

Pruning and upkeep

The radish is not pruned, but it calls for careful thinning, the most important operation in its cultivation. Sown too thickly, it makes plenty of leaves and no root. As soon as the seedlings have two true leaves, thin them to leave two to three centimetres between each plant.

To avoid having to thin too much, sow thinly from the start, one seed every two centimetres. The young plants pulled out when thinning can in fact be eaten in salad, leaves included, nothing is wasted.

Pests and diseases

The cabbage root fly can lay at the collar of the radishes, and its larvae tunnel galleries into the roots that make them inedible. An insect-proof fleece laid from sowing is the surest defence, and it also keeps the fly away from the other brassicas.

Flea beetles are the other plague, especially in dry, hot weather. These tiny jumping beetles riddle the leaves with small round holes and weaken the young plants. Soil kept moist bothers them a great deal, and a fleece stops them. Slugs, for their part, attack the seedlings in wet weather.

Propagation

The radish is always sown in place, straight in open ground, because it does not like being transplanted. Sow in rows fifteen centimetres apart, or broadcast on a small bed, only one centimetre deep. Cover with fine soil and water.

To harvest continuously, sow a small row every two or three weeks from March to September rather than one large sowing all at once. Emergence is very fast, often three to five days, and the harvest follows three to five weeks after sowing depending on the season.

Month-by-month care calendar

Green Hub tips

• Sow little but often, a small row every two or three weeks, rather than one large sowing at once that all comes together.
• Water makes the radish. Regular watering without swings gives tender, mild roots, a lack of water makes them hollow and hot.
• Lay an insect-proof fleece from sowing. It is the simplest defence against the cabbage root fly and against the flea beetles that riddle the leaves.
• In high summer, sow in partial shade or take a break. In sun and heat, the radish bolts before it even forms its root.