Horseradish (Armoracia rusticana) is one of the oldest cultivated plants and often occurs wild along paths. The plant is regarded as a pointer plant for fallow vegetable gardens. Even after many years, when the beds have long since been grassy, horseradish shows that a vegetable garden was once planted in its surroundings. The plant with the sharp roots belongs to the cruciferous family (Brassicaceae).
The cultivation of horseradish has been documented since the 12th century. Hildegard von Bingen already mentions in her botanical writings the value of the aromatically sharp roots as medicinal and aromatic plants. Horseradish is the name given to horseradish in Austria. The word “krenas” comes from Slavic and means “crying” and probably comes from the fact that the eyes tear when rubbing the fresh sticks – similar to onions. The cultivation of horseradish in the garden is worthwhile, because only freshly excavated sticks still contain all the aromatic substances and develop their fine spiciness in the kitchen. Grated horseradish is eaten with beef, sausages or smoked fish.
Location and soil
Kren is a perennial, hardy shrub that grows on almost all soils and also thrives in semi-shade. In deep and humus soils, however, it forms particularly beautiful and tasty sticks. While horseradish develops less aroma and seasoning on light sandy soils, the sticks on very loamy soils quickly become fibrous and tend to become woody. In most gardens, horseradish is kept at the same location for years. Once it has been planted, it is difficult to remove, as it also sprouts from small root parts. It should therefore be planted on the edge or outside the bed.
Cultivation and planting
In the bed, horseradish develops into an overhanging plant. The edible taproot of the horseradish plant develops several lateral roots, so-called “fencers”, over which it is propagated. They are available on the market at planting time. Make sure that the rhizomes are one to two centimeters thick and 25 to 30 centimeters long. In case of need, you can get a fresh stick from the grocer and put it – just like the fencers – in a sunny corner of the garden about 15 centimeters deep and at a slight angle into the ground from the beginning of April to the beginning of May. The planting distance is at least 60 centimeters. These seemingly large distances are necessary because a horseradish plant needs a lot of space around it. Then cover the spot several centimeters high with garden soil or mature compost. Who wants to harvest larger quantities, plants it in deeply loosened beds with a sufficient layer of compost in a distance of 70 to 100 centimeters and a row distance of 15 to 20 centimeters.
So the poles grow straight
If you want to save yourself cleaning work and achieve particularly straight poles, use the so-called “Spreewald method”, in which root cuttings are cut annually and the roots can grow back fresh. To do this, separate the side shoots of the roots in autumn and cut them into root cuttings. These should be one to two centimeters thick and at least 25 to 30 centimeters long. Two to three fencers can be harvested per plant. Bundle the fencers, wrap them in damp sand for the winter and winter them in a cellar that is not too warm. Before planting, from the beginning of April to the beginning of May, the fencers are driven forward so that unwanted shoots can be seen better. To do this, place the side shoots in a warm place under a dark foil. After two to three weeks, the spots for unwanted shoots – called “eyes” – are clearly visible. You can rub these with a cloth in the middle part. Leave all eyes in the area of the upper and lower three centimeters, however, because new roots should sprout there.
Planting: Place the fencers diagonally into the ground – the upper end should be buried about five centimeters deep, the lower end 15 centimeters. The poles should all point in the same direction. Press the soil down well and water if necessary. In June or July, when the leaf shoots are ten to twelve centimeters long, uncover the roots at the top of the soil. Caution: The lower part must remain in the ground. Cut off all lateral shoots and cover the root with soil again.
Horseradish forms thick stalks only in moist soil. So water the horseradish thoroughly once or twice a week when it is dry. The application of compost before the spring shoots ensures the supply of nutrients, whereby hardly any fertilization is necessary for domestic use. Attention: Horseradish tends to proliferate! Each piece of root remaining in the soil continues to grow. Therefore, horseradish planting should be well planned. If necessary, you can work with rhizome locks.
Crop rotation and mixed cultivation
If you only grow individual plants for your own needs, you do not need to observe any particular crop rotation. Who cultivates larger quantities: A maximum of two years in one area, then a four-year break. Good previous fruits are, for example, well-fertilized root crops.
Horseradish is traditionally harvested from October to January, with the main harvesting season being November. In the garden you can get the hardy roots out of the bed all winter long on frost-free days. To do this, lift them out of the ground with the digging fork, turn the leaves and brush off the adhering soil. When digging out the rhizomes, make sure that roots that are to be stored are not damaged. Cleaned roots should be stored quickly. Cut root pieces, wrapped in a damp kitchen towel, can be kept in the refrigerator for another two weeks.
Using horseradish in the kitchen
Directly after harvesting, horseradish does not release any aroma. Cutting, however, becomes a tear-racking affair, as the biting mustard oils produced during rubbing rise piercingly into the nose and irritate the mucous membranes. Those who process larger quantities should preferably work on open windows. After washing, you can also peel the roots thinly with a peeler and crush them in a food processor. In Austria, freshly grated horseradish is often processed into apple horseradish and served as a spicy side dish with roasted or cooked meat. This mixture can be kept in the fridge for one day. The grated horseradish remains white when sprinkled with a little lemon juice.
Diseases and pests
Horseradish is hardly likely to develop diseases in small-scale cultivation. White rust, which belongs to the downy mildew fungi, sometimes occurs in commercial cultivation: milky, puff-shaped patches appear on the underside and top of the leaves, which tear open and dust spores that can spend the winter in the soil. Furthermore, the fungus hibernates as mycelium in sick foxes. If the infestation is severe, the leaves die and the root heads rot. Remove infected plants immediately and do not multiply. As a precaution you can spray horsetail tea. Earth fleas can also occur, but they do not cause much damage.
diversity of varieties
Individual varieties are not known. In the traditionally large cultivation areas there are their own selections (“Bayrischer”, “Österreicher”, “Steirische Auslese”, “Edelkofener”, “Nederlinger”). These differ in: Size and root, leaf shape, taste, consistency and resistance to fungal diseases.
Wasabi: The Japanese Horseradish
Wasabi is traditionally freshly grated on a shark skin grater and is very hot. Fresh wasabi roots (Eutrema japonicum) are very difficult to obtain from us and are an exclusive treat due to the high prices. Wasabi paste or powder from the supermarket are mostly imitations of horseradish powder and dye. The Wasabi share of many products is just two percent. Wasabi is only conditionally hardy and much sharper than European horseradish. Tip: When heated, the essential oils evaporate, horseradish and wasabi lose their sharpness and aroma. Therefore, do not add the rasp until shortly before the end of the cooking time – unless you have got a little too much. In this case, simply let the dishes simmer a little longer.
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