Horseradish: an overview of this spicy root

In its different forms, horseradish brings spiciness to the kitchen. However, the cultivation of this plant does have several unique features.

Horseradish (Armoracia rusticana) belongs to the cruciferous family (Brassicaceae). Of main interest is the long, thickened taproot – this is where the pungency of the horseradish comes from. It is native to southern and eastern Europe. In this country, however, it has also been cultivated since the Middle Ages and can also be found in its wild form along roadsides. The plant, which grows up to one metre, is very robust and can withstand frosty temperatures of up to -50 °C. In the winter, the above-ground parts of the plant dry out, but the root will always sprout again the next spring. A special feature of horseradish is that it is almost impossible to propagate by seed, because very few seeds are formed. Therefore, the sharp plant is multiplied by lateral roots (called sets).

Growing horseradish

The right location

Ideally, horseradish will be in the brightest possible location. However, it is more important to make sure that the soil is loose and easy for roots to take hold. These properties can be provided, for example, by a loamy sandy soil or loess. This allows the root to develop well and achieve optimal thickness growth. Horseradish is also very sensitive to salt. Soils that are too salty should therefore also be avoided. Since horseradish develops a considerable taproot, it is not particularly suitable for growing in containers.

Propagating horseradish

Horseradish has very little seed formation. Therefore, particularly in commercial cultivation, it is not propagated by seed. And horseradish seeds are also not available in garden stores, instead you’ll find young plants. The propagation of horseradish occurs via lateral roots. During harvesting in autumn, the side shoots of the taproot are cut off and initially stored in sand heaps. Then, from the end of March, they are put into the ground. Care must be taken to ensure that the sets are not inserted horizontally or completely vertically into the ground. If they lie horizontally, they will not really increase in thickness; if they lie vertically, almost all the energy flows into the growth of the above-ground herb, and hardly into that of the taproot. About a month after the side roots are planted in the bed, they sprout. The process can be accelerated by forcing the roots in the warm for a few weeks. Care should be taken not to completely cover the fencing with soil when planting. The top 3 cm of the obliquely planted offspring should be left free of soil.

Tip: Think carefully about where to plant out the horseradish – since even small root pieces can develop into new plants the next year, the cruciferous plant can spread rapidly and permanently in the bed. In our growing instructions you will find everything you need to know about growing horseradish.

Watering and fertilising

Especially in the growing season, water abundantly. Horseradish achieves optimal growth only when there is constant moisture in the soil. So despite the cultivation in the bed, and depending on the type of soil, watering may be required twice a week. The supply of sufficient nutrients can be ensured by incorporating organic materials such as manure or compost. This step should be done as early as the autumn, because the incorporation of the organic material immediately before planting is not conducive to the growth of horseradish. Alternatively, you can also add a dose of tomato fertiliser to the planting hole at planting.

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Caring for horseradish

To achieve stronger taproot growth, you can lift the plant in June to remove the lateral roots that are already developing. However, the amateur gardener should be aware that the removal will cause wounds on the root, increasing the risk of infection with root diseases.

Horseradish varieties: different origins

There is no such thing as different horseradish varieties per se. However, over decades and centuries, characteristics have developed as a result of targeted selection in the cultivation area. For example, depending on its origin, horseradish may differ in odour, taste, and vigour from specimens grown in another area.

Harvesting and storing horseradish

Harvesting horseradish

The main interest in horseradish, of course, is the taproot. However, young sprouting shoots can also be harvested and used in the spring. The roots, on the other hand, should not be harvested until the foliage begins to wither in the autumn. Then the root growth is completed. This occurs around the end of October. The taproots can then be harvested and stored in their entirety, or just a few can be removed from the soil. Indeed, thanks to the pronounced winter hardiness, the plants can also be left until the next spring and harvested fresh as needed. If you are not yet satisfied with the root size, you can leave the horseradish in the bed for a second year, allowing it to sprout again in the spring.

Storing horseradish

A rather elaborate method, dating back to times before refrigerators, to prolong the usability of horseradish is to store it in damp sand. In this process, the harvested taproots are piled up in so-called clamps in the open air and preserved by the moist sand while also being protected from frost. More simple is the cooling of the crop. Optimal temperatures are between -2 and -5 °C. At even lower storage temperatures, the root loses its consistency and firmness. This means the horseradish remains usable for several months, but it does lose its characteristic pungency with increasing storage time. Because it would lose flavour and pungency, horseradish cannot be dried.

You can find even more interesting facts in our article on harvesting & storing horseradish.

Use in the kitchen and as a medicinal plant

Horseradish develops its pungent odour and flavour only when cut or grated. In the kitchen, the taproot should also be used fresh, and not cooked. Boiling or frying loses the flavour and pungency. A classic form of preparation is mashing and mixing with vinegar. This paste is often served with fish dishes or hearty meat dishes such as sour meat. Various flavour combinations are available in the form of cream horseradish. For example, cranberry cream horseradish is often eaten with game.
If you decide in June to remove the lateral roots for the sake of greater thickness, you can also make a tea from it. Thanks to its high vitamin C content, horseradish is said to strengthen the immune system. In addition, its antimicrobial effect has been proven. In addition to its healing properties gained through its consumption, horseradish was even reputed to have healing properties in the Middle Ages when worn in disc form as a necklace around the neck.

However, in addition to the pungent root, the above-ground shoots of horseradish can also be used in cooking. Briefly fried, the young shoots are super as a springtime snack. Japanese wasabi (Eutrema japonicum) – also known Japanese horseradish – is not closely related to horseradish, but they are used very similarly. Distinguishing features: Wasabi is still a lot sharper and green. Due to the much higher price of real wasabi, the greenish wasabi paste in Japanese cuisine usually contains a high proportion of the cheaper horseradish.