Growing kohlrabi in the garden

The vitamin-rich cabbage vegetable kohlrabi (botanical: Brassica oleracea var. gongylodes L.) must not be missing in any garden. It grows very well in both Central and Western Europe under the local climatic conditions. Since it only takes a few weeks from cultivation to harvest, it is possible for every hobby gardener to sow the kohlrabi again and again. Growing this tasty vegetable is easy if you follow a few crop rotation rules. There are different varieties in terms of planting and ripening time as well as color.

Location

The kohlrabi likes a sheltered, warm and sunny location.

Site characteristics and crop rotation

The development time of kohlrabi is quite short, so it is often cultivated as a preceding, intermediate or subsequent crop. For example, it can stand between runner beans or as a subsequent crop on harvested beds with peas. Planting at the edge of a cucumber bed is also possible. This protects the young cucumber plants and makes good use of the space. Since the kohlrabi belongs to the cruciferous vegetables, it should not be in a bed with other cruciferous and cabbage plants. And in crop rotation, at least one pause in cultivation of kohlrabi and other brassicas per bed must be aimed for for three to four years. Crop rotations that are too short would otherwise increase the risk of the kohlrabi being infected with soil-borne diseases such as clubroot. For this he gets a new place on another bed. However, all types of vegetables are suitable as a subsequent crop for the kohlrabi.

Floor

The soil should be medium-heavy to very rich in humus for the kohlrabi. Therefore, the soil must be prepared accordingly. It is best to work in rotted compost or fresh stable manure in the autumn beforehand. Poor sandy soils can also be supplied with half-rotted compost so that the soil contains the appropriate nutrients for the kohlrabi. Because this type of vegetable is one of the so-called medium-eaters.

Cultivation in mixed culture

If you want to grow the kohlrabi in mixed culture, the following neighbors are suitable:

• tagetes
• radish
• marigolds
• bush beans
• Peas
• tomatoes
• Beetroot
• spinach
• Leek
• celery

Pour

If kohlrabi is not watered enough, it shoots up and quickly forms flowers and no bulbs. That's why kohlrabi needs constant watering, especially in summer. Sufficient watering also prevents the tuber from becoming woody or bursting.

Fertilize

Despite a good bed preparation in autumn, kohlrabi needs a nutrient enrichment of the soil in the form of regular, small amounts of fertilizer. Nettle manure, horn shavings and other organic fertilizers are suitable for this.

Beautiful kohlrabi varieties

Not all kohlrabi are the same. Firstly, there are white and blue to purple varieties, and secondly, within this division, there is great variety in terms of flavor and tuber size.

White Varieties

Cossack:

• very leafy
• rounded shape
• robust F1 hybrid with crop security
• comparatively late harvest
• large and bursting
• still tender even in enormous size
• up to 3 kg harvest weight possible
• sunny to partially shaded location
• Sow from March to June

lanro:

• rounded shape
• cold resistant
• earlier or later extension possible
• rapid growth gives juicy flesh
• also not woody in oversize
• Sow March to April
• sunny or partially shaded location
• also under film and fleece

Blue Varieties

Blaro:

• Forced and free range kohlrabi
• for early summer and autumn cultivation
• little inclination to shoot
• medium-strong and medium-long stalked
• semi-erect growing
• high stress tolerance
• cold tolerant
• does not become woody
• medium-sized, flat round shape
• from March to June

 Azure Star:

• for all harvest windows
• does not become woody
• doesn't shoot
• medium thick, fine-stemmed foliage
• slightly flattened tuber
• high stalk
• fine taste
• earliest forcing and outdoor varieties
• Sow until late July for fall harvest

multiply

You can grow kohlrabi plants yourself or obtain them from specialist retailers. Depending on the variety and season, from sowing to harvest, approx. 12 to 20 weeks pass.

sowing

Single pots with approx. 5 cm in diameter and normal, finely sieved garden soil or potting soil from the garden center. A bright, warm location at a temperature between 15 and 18 °C is necessary for germination. As soon as the first leaves have developed, the seedlings are placed a little cooler. However, the temperature must not fall below 10 °C, otherwise the plants will no longer want to develop tubers later. But keep the plants moist. Direct sunlight is not recommended at the location. You can sprinkle the surface of the soil in the pots with some perlite or place a collar of fleece paper around the plants. Bright, light-reflecting material gives the plants more light and makes them grow more compactly.
From May, outdoor cultivation is also possible. However, waterlogging should be avoided at all costs, otherwise the small plants can easily become moldy!

planting

As soon as the seedlings have 3 to 5 rich green leaves, they can be planted out. The earliest planting date for cold frames and unheated greenhouses is the beginning of March. From mid-March, the young kohlrabi plants can be planted directly in the bed under foil or fleece. Depending on the variety, the planting distance is 30 or 50 cm. Cultivation in raised beds is also possible.

Harvesting and Storage

Kohlrabi tubers are harvested in different sizes, depending on the variety. It is best to follow the information on the seed packet. There you can read about the size of each variety. But always make sure that the kohlrabi does not get too big. Some varieties then become woody. Use sharp pruning shears or a sharp knife to cut the kohlrabi just above the base of the stalk. You can store kohlrabi harvested in autumn in a cool cellar for a while.

diseases and pests

Pests and diseases can always occur with kohlrabi, even with optimal neighborhood and companion plants and good care.

Clubroot (Plasmodiophora brassicae)

Clubroot is a fungal disease in which the fungus invades the roots from the soil and primarily damages plants from the cruciferous family. Signs of infestation are visible yellowing of the leaves with signs of wilting when exposed to heat. If the plant is severely affected, the roots will thicken. These lead to stunted growth. Clubroot occurs primarily where there is intensive cruciferous crop rotation. The fungus can also occur in soils with a low pH value, waterlogging and poor soil structure. Clubroot can be combated, for example, with a radical soil cure:

• first loosen the soil deeply
• Lime the floor heavily and mix in the lime well
• add hummus
• Green manure for half a year
• Kohler flea (Phyllotreta)

The carrot fleas are erratic, small beetles up to 4 mm in size that cause feeding damage. There are different types. The beetles found on the cabbage are blue-black in color and shiny. Flea beetles often occur when the plants are no-till when the plants are young and the soil is too dry.

Combat:

• Irrigate soil frequently
• improve plant growth conditions
• loosen the soil surface
• the beetles avoid rough soil
• Cabbage midge (Contarinia nasturtii)

The cabbage ringworm midges are extremely small and are not so common in kohlrabi. The damage comes from their tiny larvae. They cause a cripple or heartlessness in the plant's growing point. Scabs can sometimes be seen in the heart area.

Combat:

• is rarely necessary
• Mulch and plow infested crops after harvest
• thus the development of the larvae is prevented
• Lesser Cabbage White (Pieris rapae)

The damage is caused by the 25 mm long, light green to dull green caterpillars of the butterfly and becomes apparent in the pitting on the leaves from the end of May. Without countermeasures, a total failure can occur.

Combat:

• Collecting the caterpillars and eggs
• Colonization of parasitoids, such as parasitic wasps, caterpillar flies and chalcids
• Parasitoids lay their eggs inside the caterpillars
• or use biological insecticides

Conclusion

The kohlrabi is a wonderful vegetable that every hobby gardener should grow. Since it is very easy to grow, even beginners can grow it. Just keep in mind that there are early and late, blue and white, large and small varieties that need different growing times. In general, the kohlrabi likes a sunny location and lots of organic nutrients so that the tuber can develop well.

Learn more about types of vegetables