Sow radishes little and often and make sure they grow well without any checks to their growth.
Sow seed thinly 13mm (0.5in) deep, and try to aim for one seed every 2.5cm (1in). Sow 23cm (9in) apart for winter ones; this will then minimise the need for thinning later on. If sowing more than one row, space rows 15cm (6in) apart.
Sow from March to mid-August; or for an early crop sow in February in pre-warmed soil and protect with cloches.
Summer cultivars are sown from March to mid-August; for an early crop sow in February in pre-warmed soil and protect with cloches. Winter cultivars are sown in July or August.
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.
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.
‘Marabelle’ AGM - A small-leaved variety with round, small, bright red roots.
‘Sparkler’ AGM - Medium-sized roots coloured pink with a white base. Reliable, easy and fast to mature.
‘French Breakfast 3’ AGM - A long, cylindrical radish, red with a white tip.
‘Ping Pong’ AGM - Producing a very uniform crop of solid, round, white roots that are crunchy, juicy and have a mild flavour.
Flea beetle: Attacks by flea beetle cause lots of tiny holes in the leaves.
Remedy: The damage is only superficial, so usually not worth worrying about. If it is a particular problem in your garden you can cover the seedlings with horticultural fleece.
More information on flea beetle
Slugs and snails: Feed on the young seedlings. You’ll see the tell-tale slime trail of slugs and snails 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 and copper tape. Slug pellets of powders based on aluminium sulphate or ferric phosphate are less toxic for wildlife.
More information on slugs
More information on snails
Brassica downy mildew: This is a common disease of brassicas, but less so on radishes, as they are not in the ground so long. The leaves will turn yellow, with white, fuzzy patches on the undersides. The radish root may also turn brown.
Remedy: Remove infected plants as soon as you see them. Don’t plant radishes in the same place as previous brassica crops. There is no chemical control.
More on brassica downy mildew