How to grow horseradish

Horseradish (Armoracia rusticana) forms a large leafy clump that looks like a very vigorous dock, about 60cm (2ft) tall and wide. This long-lived

Perennials are plants that live for multiple years. They come in all shapes and sizes and fill our gardens with colourful flowers and ornamental foliage. Many are hardy and can survive outdoors all year round, while less hardy types need protection over winter. The term herbaceous perennial is used to describe long-lived plants without a permanent woody structure (they die back to ground level each autumn), distinguishing them from trees, shrubs and sub-shrubs.

Dormancy refers to a period of inactivity in plants, during which they slow down or stop their growth, conserving energy and resources. This is a natural process that helps them survive harsh conditions, such as winter or drought. Dormancy in seeds is a mechanism that prevents them germinating until environmental conditions are favourable for growth.

dormant

Horseradish leaf - Armoracia rusticana

There is only one form of horseradish widely available – Armoracia rusticana. This is fully hardy, vigorous and long-lived, and best planted in a container to limit its spread. 

Horseradish seeds are rarely available and much slower to reach harvesting size, but can be sown outdoors in containers in spring – see our guide to sowing outdoors.

Horseradish is easy to grow from long pieces of root (thongs) or from young potted plants. These should be planted in spring or early summer, ideally in a large container, in sun or partial shade. They can also be planted in a small raised bed or similarly enclosed site.  

It’s best not to plant horseradish in open ground, as it forms a vigorous spreading clump that can be hard to control or remove, as it will root in deeply and re-grow from any pieces of root left in the ground. 

Planting is very easy: 

• horseradish roots (known as thongs) – plant up to three in a 30cm (12in) pot filled with multi-purpose compost. Make a deep hole with dibber or trowel handle, insert a root vertically so the top is 5cm (2in) below the surface, cover with compost and water well. You can also plant in a similar way into a small, raised bed 

• young horseradish plants – plant one or two small plants in a 30cm (12in) pot filled with multi-purpose compost, or in a raised bed – space them up to 30cm apart if you want several clumps

Once established, horseradish is vigorous, robust and low maintenance, although plants in containers need watering on a regular basis.  

Horseradish is harvested once the leaves die back in autumn or winter, ideally after frost, which enhances its flavour. If harvested at other times of year, the roots will have less of a kick. 

Tip the plant out of its container and remove up to half of the slender white taproots. Replant the remaining roots back in the container, in fresh potting compost. The replanted roots will burst back into growth in spring, sprouting a flush of new leaves. 

If the horseradish clump is growing in a raised bed, simply lift what you need with a garden fork. Harvesting some of the roots annually helps to control the spread of this very vigorous plant. 

Horseradish roots will add a fiery punch to many dishes. Simply peel the root and grate it raw into mayonnaise to make an easy horseradish sauce, a traditional favourite with roast beef. It can also be used to pep up hearty stews, pasta sauces, salad dressings, dips, mustard and much more. It can also be used as a replacement for wasabi. 

Once grated, horseradish should be used quickly as it will discolour and the flavour may fade. But whole roots store well in a cool, dark, frost-free place – bundle them together in a wooden box or tray and cover with damp sand. Or store in an airtight container in the fridge for up to several months. 

Horseradish is a tough, hardy and vigorous plant that is rarely troubled by any pests or diseases.  

The only common problem is that is can be overly vigorous, so make sure you plant it in a container to limit its spread. Horseradish can be hard to control in open ground, as the roots go very deep and if you dig it out it will re-grow from any pieces of root left in the soil. See our guide to controlling vigorous plants.