Kohlrabi is one of the hardiest vegetables, but you can still make mistakes when growing it in your garden at home that do not result in a satisfactory harvest. These are quick to make, especially since kohlrabi cultivation does not require the same procedures as are usual with other types of cabbage. If you follow the cultivation instructions from the plant expert, it will work without any problems.
Kohlrabi
The kohlrabi is usually not very demanding. If you pay attention to the most important factors in care and cultivation, you can harvest after just a few weeks. The turnip cabbage, as it is called in Switzerland, can be self-propagated, is suitable as a plant neighbor for many other types of vegetables and offers you different varieties with different properties. In Hausgarten-Magazin you will receive professional instructions that also make it easy for laypeople to grow kohlrabi.
location
The Brassica oleracea var. gongylodes L, known in botanical jargon, thrives in regions with a moderate climate, which is why it can be grown well in sunny locations in western and central Europe. As a young plant, it should be warm in the sun. In autumn, it easily tolerates a partially shaded spot. Depending on how sensitive it is to cold, it should be sheltered from the wind.
crop rotation
Due to its usually rapid growth, the kohlrabi requires sufficient nutrients. For this reason it should not be grown in the same spot where it was already standing for a period of four years.
mixed culture
Also due to the high nutrient requirements, it is advisable not to grow Brassica oleracea var. gongylodes L. next to heavy-consuming plants or vegetables from the cabbage family. The following plants, for example, are ideal as plant neighbors.
- salads
- spinach
- pole beans
- cucumbers
- Beetroot
- peas
- radish
pre and post culture
The kohlrabi can usually be grown as a pre-culture for almost all types of vegetables. Only with plants from the cabbage family should you refrain from pre-cultivating. The waiting period here extends to a period of at least three, preferably four years. The turnip cabbage is ideal as a follow-up culture. But also the rule: do not grow in places where other types of cabbage have grown in the last three to four years.
soil condition
Since the upper kohlrabi (common name) only spends a very short time in the ground before it is harvested, its demands on it are limited. However, there are a few points you should keep in mind.
- medium-heavy to humus-rich
- nutritious
- even humidity
- permeable
- no waterlogging
- pH around 7.0
Best planting time
Top beets can be sown between spring and late summer. Depending on the variety, you can harvest until autumn due to the relatively short time until it is ready for harvest. The earliest time for planting/sowing outdoors is mid-March. Since the temperatures are usually still cold here, the sowing should be protected from the cold with fleece or foil.
As a rule, the last sowing for an autumn harvest should have taken place in June. It will be over by July at the latest. Here, however, you should also protect the seed with a fleece or a translucent film from cool temperatures.
TIP: If you want to harvest throughout the season, sowing every two weeks is recommended. However, this assumes that there is enough space.
Early kohlrabi
Alternatively, kohlrabi in a plant pot is preferable. This can be done from the end of February/beginning of March. The preferred plant is usually ready for planting in the vegetable patch from April when the temperatures are warmer.
Kohlrabi sowing
Once a suitable location has been found that meets the requirements of the cabbage plant, you can start sowing as described below.
- If necessary, enrich the soil with compost
- if the seed is always sown in the same place, compost enrichment every two to three years is sufficient
- The same applies if kohlrabi is planted as a follow-up crop for weak eaters
- Moisten the soil well
- Scatter seeds about one to two centimeters deep in the soil
- Cover the seeds with a maximum of two centimeters of soil (dark germs)
- Sowing distances: early and summer varieties: 25 to 30 centimetres, large kohlrabi varieties 40 to 50 centimetres
prefer kohlrabi
If you want to prefer the turnip, spread the seed in a seed box or suitable plant pot. This is particularly useful if you want to harvest early, because you can start sowing in heated rooms at the end of February/beginning of March by pulling them forward. The first harvest is therefore possible early in the year.
It is advantageous if you use nutrient-rich substrate or special growing soil. Proceed as you would with outdoor sowing. You should also consider the following points.
- Ambient temperature: between 15 degrees Celsius and 18 degrees Celsius
- after about four weeks the young plants can be pricked out
- once leaves have formed, the young plant can withstand cooler temperatures of up to ten degrees Celsius
- if the outside temperature corresponds to the minimum height, the young plant can be planted outdoors
set seedlings
When planting seedlings, prepare the soil in the same way as previously described. Also, note more details about typesetting as listed below.
- Planting distance: at least 20 centimetres, depending on the final size of the respective variety
- Row spacing: at least 30 centimetres, depending on the final size of the respective variety
- Planting depth: depending on the size of the seedlings, about five centimeters - not too deep, otherwise there is an increased risk of lignification
- Press the soil surface lightly
- keep evenly moist
- Avoid waterlogging
greenhouse sowing
Sowing and growing kohlrabi in greenhouses is possible all year round. The prerequisite is that the temperatures are constantly at least between 15 degrees Celsius and 18 degrees Celsius if the seeds are continuously sown in the greenhouse. The vegetable cultivation experts speak here of greenhouse kohlrabis. These differ from those from the field by their tender flesh. In terms of taste, however, they show up with a minimally insignificant aroma.
pour
An important criterion for the magnificent growth of a kohlrabi is the optimal moisture content. The Brassica oleracea var. gongylodes L. should be kept constantly moist and should have a constant moisture content from sowing to harvest. This means avoiding large fluctuations or a dry soil. This would result in the risk of lignification of the tuber. This could also burst.
The kohlrabi must not be too damp either. This would slow him down in tuber growth, although the leaves would sprout vigorously at first. He does not tolerate waterlogging. If you keep the soil moderately moist, it can grow vigorously. On hot summer days and prolonged dry spells, that means you'll be spending some time watering.
Fertilize
The cabbage plant has a high nutrient requirement. As a rule, it is sufficient if the soil is enriched with nutrient-rich fertilizer when sowing. Compost is ideal. However, it is more advantageous if he is given small doses over a longer period of time. If you enrich the soil with nutrient fertilizer in autumn before sowing for the first time, this can be optimally distributed until the following year. Additional fertilizers during growth are not required. Soil enrichment usually provides enough nutrients for two to three years.
harvest
The kohlrabi has a relatively short ripening time. Many early varieties are often ready for harvest after just eight weeks. Above all, large-growing kohlrabi varieties usually need between ten and twelve weeks until the optimal degree of harvest is reached. Basically, when harvesting, you should use the expected final size as a guide, as stated on the sowing bag. This is the case, for example, with small bulbous specimens when they have reached the size of a tennis ball.
You should strictly follow these instructions and harvest when the size is reached. If you wait too long, hoping for a few centimeters more, you run the risk of the tuber becoming lignified and no longer edible. The kohlrabi is cut off directly below the tuber. A sharp knife works best for the process.
TIP: When harvesting, make sure that you only use disinfected cutting tools, especially if you are using them to cut other vegetables. Cutting tools are the most common carriers of bacteria and viruses that can destroy an entire crop.
propagation
You can obtain seeds from planted stocks yourself and do not have to buy them expensively in specialist shops. For propagation, leave the kohlrabi in the first year and refrain from harvesting. It will start blooming in the second year if you cover it with straw or twigs during the cold winter months. After pollination in late spring/early summer, the seeds grow. They usually reach maturity in July and can then be collected.
It is important that you dry the seed after collecting it before it is sown. Since the outdoor sowing season ends in July at the latest, it is advisable to store the seeds in a dry place over the winter until next year. The kohlrabi tuber is no longer edible after flowering.
Diseases
Turnips are considered robust vegetable plants, but occasionally diseases can creep in, which are mainly typical of cabbage plants.
Cauliflower Mosaic Virus
Symptoms usually appear in the form of lightening of veins between dark green leaf areas, growth disorders, brittle leaves and leaf fall. The viral disease is transmitted by the mealy cabbage aphid and other louse species. There is no soil infection.
Treatment:
There is no specific treatment for infested kohlrabi. The plant must be removed immediately and neighboring plants protected against aphids over a large area. With roses, false jasmine, elderberry, hibiscus and redcurrants in the vicinity, you will distract aphids from your kohlrabi. Natural enemies of aphids, such as lacewings and ladybugs, which eat hundreds of aphids every day and thus prevent them from spreading, help preventively. You can attract natural eating friends yourself or obtain them from the garden trade.
Clubroot
One of the most feared diseases of Kohlrabi growers is clubroot. Early varieties are particularly susceptible. Infection occurs via soil-dwelling parasites called Plasmodiophora brassicae. These damage the root, which subsequently forms cancer-like adhesions that begin to rot. This forms spores that kill kohlrabi.
Typical symptoms are growth disorders, discolored and falling leaves and bulbous, cylindrical thickening of the roots.
Combat:
Controlling clubroot is difficult because chemical soil disinfectants are not available privately in Germany. Calcium cyanamide fertilization can maximally reduce an infestation. The preventive measures described below are all the more important.
- Loosen the soil regularly
- Check pH - should always be between 6.8 and 7.0
- do not use strawberry beds for kohlrabi cultivation
- Adhere to the cultivation waiting period of at least four years if cabbage / cruciferous plants were previously planted
Wrong mildew
Rarely does fungal infestation occur with downy mildew. You can recognize this above all by a mealy, white, slightly violet shimmering fungal coating on the undersides of the leaves. Leaf discolouration, which initially becomes light and later darker, occurs on the upper side of the leaf. Treatment with soapy water is particularly promising in the early stages and preserves the edibility of the kohlrabi.
pests
Next to the aphids finds him every now and then cabbage weevil its way onto the kohlrabi. There he lays his eggs. The larvae eat their way into the interior of the stalk and cause damage there that causes the tubers to burst open. Eaten leaf midribs and broken stems are typical signs. The only way to combat them is to use insecticides from the group of pyrethroids class II, such as Bulldock, Fastac SC Super Contact or Sumicidin Alpha EC. However, the harvest is now obsolete.
sorts
Depending on the variety of stalk beet, these differ in their properties, such as early or late cultivation, taste and growth rate. Some common varieties include those listed below.
azure star
- purple tuber
- grows strong
- early variety
Blaro
- reddish-purple tuber
- early cultivation
- cold tolerant
- bolt proof
- above average delicate aroma
- very profitable
Blue bacon
- red-blue tuber
- growing fast
- early variety
- sensitive to frost
- well storable
White delicacy kohlrabi
- light green tuber in a flat, round shape
- a lot of aroma
- tender
- medium growth rate
Express Forcer F1
- fast growing
- precocious
- delicate and aromatic
- is mostly grown for sales purposes
giant
- late harvest due to slower growth
- high tuber weight possible
- can be stored well
Konmar F1
- most common variety
- light green tuber
- mild aroma
Kossak F1
- oval, light green tuber
- Bulb weight up to four kilograms possible
- fast growing
- high demand for space
lanro
- light green tuber
- early variety
- profitable
- bolt proof
- very tasty and tender meat
- fast growing
White Viennese
- light green, large tuber
- fast growing
- excellent aroma
- hardly lignifies
- late harvest