How to grow radishes

Salad radishes are quick and easy to grow from seed, and are ready to eat in as little as four weeks. These compact plants can be grown in even the smallest of spaces and are great gap-fillers on the veg plot. Sow small batches every few weeks to add a crunchy kick to salads in late spring and summer. There are also winter cropping, oriental and edible-podded varieties. 

Salad radishes are ideal for spring and late summer sowings

Grow a range of varieties to add colour and flavour to salads

• Salad radishes (also known as spring or summer radishes) – these are the most popular and widely grown type. They are small and fast growing, sown in the ground or in containers in spring and summer. There are many varieties, forming small succulent roots in a choice of shapes and colours. Great for eating raw, they are refreshing and crunchy with a peppery kick. 

• Winter radishes – these hardy radishes are larger and slower growing, sown in late summer for harvesting in winter. If sown too early, they will bolt (start flowering) and the root won’t swell. Most varieties have a mild flavour, although some can be hot, so check the packet before buying. Winter radishes are mainly used in stews and stir-fries, in a similar way to turnips. The leaves grow up to 45cm (18in) tall and are edible too. 

• Oriental radishes (also known as Japanese, daikon or mooli radishes) – they usually form a long white tapering root that can be eaten raw or cooked. They are slow growing, often forming a very long root, and are usually harvested in late summer and autumn. 

• Edible-podded radishes – these varieties are grown for their long spicy seed pods rather than their root. They’re very easy to grow and crop prolifically, especially in hot weather. The sprawling flowering stems can reach 45cm (18in) tall or more, producing edible pods for several weeks. They add a peppery crunch to salads and stir-fries. 

When choosing radish varieties, look in particular for those with an RHS Award of Garden Merit (AGM), which shows they performed well in trials – see our list of AGM fruit and veg and our Recommended Varieties below. For more veg-growing inspiration, visit the RHS gardens, which all grow a wide range of vegetables, including radishes, salads and other quick and easy crops.

Choose an open, sunny site, although light shade is acceptable for salad radishes in midsummer. Long-rooted varieties of winter and oriental radish need deep soil – some can grow to more than 30cm (1ft) in length.

Remove any weeds from the area. Prepare the ground by forking through the soil to break up hard lumps and compaction, and remove any stones, then rake to a fine texture. If you’re practising no-dig,

Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings.

Radishes are easy to grow from seed sown outdoors, and

Germination is the process by which a seed develops into a new plant. It starts with the seed coat absorbing water, expanding and splitting, which allows oxygen and water into the seed so its food reserves can be broken down and used by the embryo for growth. The first root (called the radicle) pushes into the soil to anchor the new plant in place and start absorbing water and nutrients. The first shoot (called the plumule) then grows upwards, out of the soil, towards the light.

• Sow salad radishes in spring, early summer and late summer for best results – avoid sowing in hot dry weather, as plants tend to bolt (start flowering). Sow seeds 1cm (½in) deep and 2.5–5cm (1–2in) apart, with 15cm (6in) between rows. Regular small sowings will provide continuous harvests – see our guide to successional sowing. In warm weather, choose a cooler location in light shade, out of midday sun. If you want an early crop, sow from February in pre-warmed soil, protected with cloches.

• Sow winter radishes in July or August about 2cm (1in) deep, spacing seeds (or

  Pulling out some of the seedlings, usually along a row, so the remaining seedlings are spaced further apart. It reduces overcrowded, which can hinder their growth.

  thinning seedlings) to 15–20cm (6–8in) apart, depending on the variety, with 15cm (6in) between rows.

• Sow oriental radishes in spring and summer. Often called Japanese, daikon or mooli radishes, these usually have long white tapering roots, but some varieties are round or dark-skinned. Sow in a similar way to winter radishes.

• Sow radishes for edible pods in spring and summer. They do particularly well in hot weather, so are a good alternative to salad radishes in summer. Sow seeds 1cm (½in) deep and 10cm (4in) apart.

Fast-growing salad radishes are ideal for filling any gaps on the veg plot or sowing between slower-growing crops such as peas and potatoes. They can also be used as row markers for slow-germinating crops, such as parsnips and onions – the radishes germinate quickly, marking out the row where the other crops have been sown, and are harvested before they can hinder the main crop’s growth.

Thinning seedlings

Thin out dense sowings to give the radishes room to grow without too much competition

A seedling is a young plant grown from seed.

seedlings

Radishes are generally easy to grow, but they do need regular water and warm but not overly hot temperatures, so the roots grow strongly and evenly. Make sure plants aren’t spaced too closely or crowded out by weeds.

Keep radishes weed-free, and water during any dry spells to prevent the roots splitting

Although radishes are generally trouble free, especially spring sowings, you may get disappointing results if the growing conditions aren’t right. Problems can include: 

• Roots fail to swell – this can happen for various reasons, including dry conditions, heat and overcrowding. Salad radishes grow best in mild spring weather – in summer they need regular watering, especially in hot, dry spells. Make sure plants are well spaced – salad radishes at least 2.5cm (1in) apart, winter and oriental radishes 15cm (6in) apart – to give the leafy top-growth room to develop and swell the root.

• Flowering (or bolting) – this may happen in hot, dry weather, in which case the root won’t develop. Keep plants well watered over the summer and remove any that start to produce a flower stem (unless you want to harvest the edible seed pods). 

• Roots are woody, bitter or overly spicy – they are probably too old. Harvest salad radishes as soon as they reach about 2.5cm (1in) in diameter, which should only take about a month (or two months for early sowings) – don’t leave them much longer, as eating quality will suffer.  

• Split roots – this is usually caused by uneven moisture levels, so water during dry spells to ensure consistent growth. Split roots are usually still edible.

Radish plants may also be damaged by: 

• Slugs and snails – these may eat seedlings, especially in damp conditions.

• Cabbage root fly – the larvae tunnel into the roots, especially in late summer. They’re unlikely to trouble fast-growing salad radishes, but may cause problems with slower-growing winter and oriental types that are in the ground for longer – cover crops with biodegradable fleece or insect-proof netting. 

• Flea beetles – these eat tiny holes in the leaves, but the damage is usually only cosmetic and doesn’t hinder growth. 

For more information on spotting and tackling these issues, see Common problems, below.