Growing Interesting Radishes

13 August 2010, written by Jeremy Dore

Most people's experience of radishes is limited to the standard summer types found in shops – little round globes that you chop up into salads. They're an easy, reliable crop that can be grown from spring right through to early winter with little difficulty. Gardeners often treat them as an after-thought, popped into a gap between the 'real' crops. However, look a little deeper and you will discover that there is much more to radishes than the standard types – a whole variety of colours, tastes and textures are available from this versatile little vegetable.

Radishes are quick to mature so they are often recommended as an ideal vegetable for children to grow. I can't say that I agree with this as I have yet to meet a child who likes the taste although some will tolerate the milder varieties if chopped up small. In my opinion it's far better to start kids growing things they love to eat even if that does mean waiting longer for the harvest.

Radishes are easy to grow and will tolerate most soil types, without needing a lot of attention. They are typically sown directly into the soil in rows, spaced about 10cm (4 in) along with up to 30cm (12 in) between the rows. Less than this and you are likely to end up with lots of leaf but small roots. As soon as soil temperatures exceed 7°C (45°F) the first sowings can begin and the season can be extended by using cloches to warm the soil if required (although these can encourage slugs). Radishes are really cool-season crops so during hot summers it is advisable to grow then in a semi-shaded position, keeping them well watered. Very hot locations may not be able to grow them in summer – our Garden Planner can advise on times for your location.

Row of radishes — Radish sown in rows - too close and the roots will not develop

Avoiding Radish Problems

There are two main pests that affect radishes:

Flea Beetles are tiny little insects that jump when disturbed, so that gardeners rarely actually see them. You can easily see the effects though – little holes in the leaves which, in severe cases, can cause so much damage that the radishes don't mature. Flea beetle attacks are worst in hot weather, particularly during late summer. Keeping the soil around seedlings well watered can help control the problem; alternatively cover rows with fine mesh or horticultural fleece. Most important is to rotate radishes with other brassicas and weed the ground well as the flea beetle lavae can overwinter in soil and initially feed on plant debris.
Slugs will produce little pitted holes in radishes and don't seem to be deterred by peppery varieties either! See my GrowBlog article on Slugs for details of how to control them.

Radishes will typically be ready in 4-5 weeks during warm weather or 6-8 weeks at the beginning and end of season and because of this they make an ideal 'catch crop' grown in between larger slower-growing vegetables while they are still young and don't need the space. It is tempting to pop radishes into any available space in the garden but if flea beetles are a problem then it's best to rotate them to new positions each year.

Leaving radish too long will result in two undesirable outcomes: they either become 'woody' in texture or excessively peppery in taste (particularly in hot weather). That's why it is essential to practice succession planting, sowing a small quantity of new seed every 14 days so that you always have some radishes at their prime for harvesting. Watering regularly during warm spells also helps reduce woodiness.

Colourful Varieties

Various varieties of radish are readily available. The traditional red globe types also come in yellow and white-skinned varieties. Also easy to find are cylindrical shaped types such as the popular 'French Breakfast' variety. Then there are the more unusual Chinese types: Mooli radishes which produce long mild-flavoured roots, black-skinned golf-ball sized varieties for cooking and colourful types with magenta rings tinged with green on the outside. This year I have grown some interesting varieties from the Real Seed Catalogue: large 'Sicily Giant' which has produced big roots without any woodiness, 'Red Flesh' which is a Japanese variety with colourful rings and I'm still waiting for my black-skinned Austrian variety with the wonderful name of 'Wiener Runder Kohlschwarzer' to mature – apparently the heat disappears from them when cooked and they can be added to soups, stews and stir-fries.

Which radishes you select will be down to your own taste preferences. I am firmly in the group of people who like very mild tasting roots rather than the hot peppery tastes. For me it's the colour and crunch that radishes add to a salad that are the main reason for growing them. For others, the more spicy tastes will appeal and there are even varieties that you can grow for their hot seed pods rather than roots. Whatever your choice, I would recommend taking a second look at your seed catalogue and being a bit more adventurous – size, colour, taste and texture can all transform the humble radish into a proud talking point of your garden!