Horseradish (Armoracia rusticana) forms a large leafy clump that looks like a very vigorous dock, about 60cm (2ft) tall and wide. This long-lived perennial is a member of the cabbage family (Brassicaceae), related to mustard and wasabi, and is fully hardy in the UK. It goes dormant over winter, the leaves dying down in autumn then re-sprouting from the roots every spring.
Horseradish leaf - Armoracia rusticana
Horseradish is very easy to grow, thriving in sun or partial shade – so much so that it can be hard to control if grown in the ground and its deep roots can be difficult to eradicate. But don’t let that put you off – simply grow it in a large pot. Then to harvest, just tip it out and take a root (or however many you need) from the clump and replant the rest back in the pot.
Month by Month
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.
What and where to buy
Horseradish is mainly sold as long pieces of root (known as thongs), available in spring from online veg and herb plant suppliers. You may also find young plants in spring or summer in the herb section of larger garden centres. Both will establish quickly and should be large enough to harvest in their second autumn onwards.
Seeds are occasionally available, but these take longer to form established clumps – it’s much quicker and simpler to plant roots or young plants.
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.
When grown in a container, horseradish needs regular watering throughout the growing season, especially in warm weather. Once established, horseradish in raised beds should only need watering in long dry spells. The leaves may flop if plants get too dry.
Apply a thick layer of mulch, such as garden compost, around horseradish clumps to help hold moisture in the soil.
You can give horseradish plants in containers a boost in summer by applying a balanced liquid fertiliser.
Cut back the faded leaves once they die down in late autumn, or before new growth starts in spring.
One clump of horseradish is usually enough for most requirements, but you can easily make new plants to share with friends by taking off pieces of root 15cm (6 ") long when harvesting in autumn and pot them up, see planting section above. Alternatively, dig up roots from the outside of a clump in spring.
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.
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