Alys Fowler: gambling with radishes

There’s laundry pegged out on the line, the primroses are in flower, it’s the first day you can cycle without gloves and there’s a smell of life stirring. It’s not quite spring, but it is just warm enough to take a punt – and I always gamble, so to speak, with radish seeds.

Radish germinates at 8-10C, with a night-time temperature no lower than 5C. If your radishes germinate within a week, it’s a sign that the soil is warming up. If they take longer, think before you sow other vegetables outdoors. For the impatient, a covering of fleece or a cloche will help raise the night-time temperature.

Early thinning is essential. Leave it too late, and you will end up either with all leaf and no root – this also happens if you overfeed with nitrogen – or with misshapen, pithy radishes.

Thin early and you can sink your teeth into a perfectly crisp, cool radish. As soon as the seedlings are large enough to handle, you should thin them to 2-3cm in rows 10-15cm apart, or 15cm if you are planting on a grid system. For a continuous supply, sow every two weeks.

Radish’s biggest enemy is the flea beetle. This tiny metallic-black insect gnaws holes across the leaf until it looks like a doily. It doesn’t much affect root production but it will move on to rocket and other brassicas. So avoid sowing from late spring to early summer, when the beetle is breeding. Or cover with fleece or enviromesh immediately after sowing (if you wait for seedlings to emerge, you will just trap the beetle underneath). If radishes get hot and thirsty, they tend to bolt straight to seed, which is no loss, because the flowers and seedpods are also edible and much loved by pollinators.

Slugs also like to nibble away at radishes – at least until the roots mature and become spicy. If you find that yours are being munched, gently flick the soil from around the roots to unearth the culprits, then squish them.

The most popular radish variety is ‘French Breakfast’ with its cylindrical, red-and-white roots: you can pick up seed for this at pound shops. ‘Cherry Belle’ has lovely red roots and a delicious mild flavour. Likewise, ‘Sparkler’ is popular for its mild taste and resistance to bolting. As the season progresses, the spicy flavour will become more pronounced in both varieties.

I find ‘Prinz Rotin’ is particularly slow to turn pithy and ‘Amethyst’ has a purple-blushed skin with white flesh that remains crisp whatever the weather.

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