Radishes are easy to grow in any size of garden. They are fast-growing and are ready to harvest in about four weeks from sowing. Sow radish seeds every two weeks in fertile, moisture-retentive soil, throughout summer for crunchy salads. Don’t forget, there are varieties for winter too, such as mooli.
Radishes should be sown little and often, and make sure they grow well without any checks to their growth.
Summer cultivars are sown from March to mid-August; or for an early crop sow in February, in pre-warmed soil and protect with cloches. Sow seed in the spot where it is to grow. This can be in the ground, in containers or sow a couple of rows in a growbag. Sow seed thinly 1cm (½in) deep, and try to aim for one seed every 2.5cm (1in).
Winter cultivars are sown in July or August. Sow 23cm (9in) apart for winter varieties; this will then minimise the need for thinning later on. If sowing more than one row, space rows 15cm (6in) apart.
By sowing seed thinly (approximately 2.5cm/1in apart) there should be no need for thinning summer cultivars, but any that is needed should be done as soon as possible. Winter cultivars should be thinned to 15cm (6in) apart.
Keep the soil moist to ensure rapid growth, keep the roots fleshy and tasty and prevent splitting. Sowings made in July and August can be a problem due to the hotter, drier conditions, so make sure these are well looked after.
Because radishes are quick to mature they can be used as a ‘catch crop’ being sown between rows of slower-growing vegetables such as peas and potatoes. They can even be used as row markers of slow-germinating crops, such as parsnip and onion – the radishes germinate quickly, marking out the row where the other crops have been sown and can be pulled before interfering with the main crop.
Troubleshooting Growing Problems
Flea beetle: Leaves are covered in small holes and damaged areas turn brown. Seedlings are particularly susceptible.
Remedy: Grow plants under horticultural fleece and keep the soil moist. Water in nitrogen-rich fertilser to help the crop outgrow the pest.
Slugs and snails: These feed on the young seedlings and you’ll see the tell tale slime trail on the soil around your crop, as well as on the leaves.
Remedy: There are many ways to control slugs and snails, including beer traps, sawdust or eggshell barriers, copper tape and biocontrols.
Brassica downy mildew: This is a common disease of brassicas, as they are not in the ground so long. The leaves will turn yellow, with white, fuzzy patches on the undersides. The root may also turn brown.
Remedy: Remove infected plants as soon as you see them. Don’t plant brassicas in the same place as previous brassica crops.
Radishes need to be grown steadily and harvested young to ensure they remain succulent, otherwise they can become woody and inedible.
Pull summer radishes as required, making sure they are never left to mature and become woody. Winter cultivars can be left in the ground and dug up as required, or lifted in November and stored.
Plant with: beans, carrots, chervil, cucumbers, lettuce, melons, nasturtium, peas