Lars Lund

30 Mar 2023 08:35

Cultivating kohlrabi


The Brassica family is brimming with healthy cabbage. One delicious option is kohlrabi, also known as turnip cabbage. In this article, you can read how to get started with turnip cabbage.

In the old gardens, there were plenty of green cabbages, Brussels sprouts, red cabbage, or white cabbage, and underground there were kohlrabi, turnips, celery, and parsnips. Although there has been a good increase in kitchen gardens in recent years, the selection of edible crops in gardens has dwindled significantly. Only in a few gardens, you can see a real cabbage garden, but we should grow and eat more cabbage, because it keeps us very healthy. 

Cabbage is easy to grow, and the plants develop quickly. They just need a compost-fertilized soil with a pH value of around 6.5. It is also important that cabbage does not lack water. Water shortage makes them limp and almost inedible. Crop rotation is necessary, but then all the necessary conditions are met. Cabbage can also easily withstand wind and rain, and that's why they are well suited to grow in our climate. 

That's why you should eat cabbage

Like other vegetables, cabbage is very healthy. Amongst other things, it can potentially prevent lifestyle diseases. According to research at the University of Århus and the University of Southern Denmark, cabbage can contribute to preventing cardiovascular diseases and cancer, due to a high content of the substance glucoinolates. Since diet can have a major impact on the development of type 2 diabetes, cabbage can potentially also contribute to preventing diabetes.

Some refrain from eating cabbage because it gives a little unpleasant gas in the intestines, but this stops when the stomach gets used to cabbage, and the better you chew the cabbage, the easier it is to digest. If you cut it well and thoroughly, you further reduce the risk of bad air.

Turnip cabbage is among the forgotten 

Among the more or less forgotten cabbages is the turnip cabbage, also known as kohlrabi, or in Latin brassica oleracea var. It is often confused with swedes, which is a root vegetable. The German name is 'Kohlrabi' as well. Kohlrabi or turnip cabbage is as small and as crisp as an apple and can be used in all kinds of salads and stews. Although it resembles a small turnip, it is in the cruciferous family. There are white and violet varieties of the turnip cabbage, but all have white flesh.  

They are ready for harvest after 6-8 weeks of growth, typically reaching a size of 5-8 cm, and are most crisp at that size. The turnip looks a bit similar and is in the same family but is another old little thing. Here too, there are both white and yellow turnips. 


A surprising taste

Turnip cabbage surprises with its taste and is good for those who are not fond of the cabbage flavour. In fact, the thick knob that looks like a turnip is actually the swollen stem that we eat. If you're not into the taste of cabbage but still want to have all the good benefits of eating cabbage, turnip cabbage is the way to go. It tastes a bit like a broccoli stem, but milder and sweeter, and it is crispy like celery. Turnip cabbage can be stewed or eaten raw in a salad. In its raw state, it should not be woody, or the taste experience will be poor. If it is woody, it has become too large, which can be checked by cutting it into pieces. If there is woody material, it can be seen as small fibers sticking out from the surface. If that's the case, you can still use it for cooking.

Turnip cabbage is nutritious and rich in vitamins C and K1, and the minerals iron and calcium, but it is its abundance of glucosinolates that sets it apart (Source: „Super Sunde Superfood“, Mette Hellebæk & Valeria Lima, Politiken). As mentioned before in connection to the research of the University of Århus and the University of Southern Denmark, turnip cabbage has a high content of the substance glucoinolates. The glucosinolates are releasing two types of active compounds, a type of phytochemical that has an antioxidant effect. In Denmark, we have known turnip cabbage since 1786, and it is an old cultural plant that can be traced back to the Romans. It is particularly popular in Germany. 

How to grow turnip cabbage 

Limited space and good soil

The plant does not require much space. It grows to be 35 cm high and about 25 cm wide. Remember to rotate the crops. Preferably, there should not have been growing any other cruciferous plants for the past 5 years, where you plant your turnip cabbage. Cruciferous plants are a very large group with 350 sorts, where the most common in the kitchen garden are all kinds of cabbage, watercress, horseradish, and winter cress. Turnip cabbage is not very demanding when it comes to the soil, but ideally the soil should be clayey, ploughed, and nutrient-rich. 

Sow early  

Already at the end of February or the beginning of March, depending on the variety, you can sow turnip cabbage in a seedbed or your greenhouse. Make a groove in the soil and moisten it with water from a sprayer. Place each seed 1 cm deep and cover it with soil. As a rule of thumb, you should sow 5-6 weeks before planting the turnip cabbage outside. The seeds germinate after about 10 days, and if you have sown too densely, you can thin them out a bit. In May, you can plant them in the garden with 20 cm between the plants and 50 cm between the rows. Cover the plants with insect netting, as cabbage flies and cabbage moths also love them, and water as needed. You can also sow the seeds directly outdoors in a warm place where the sun warms the ground. The sprouts are fairly frost-resistant but cover them with a fibre cloth if there is frost. The plants should not lack water during their development. 


After planting, make sure they have enough water, because they should not get too dry. After a week and after 14 days, you can add fertilizer. In general, compost from the beginning when the cabbage is planted outside is an advantage.


When they are between 5-8 cm in diameter, they are ready to be harvested. Again, the rule of thumb is that they are ready after about 60-90 days. Depending on the variety, planting, and weather, this can mean from June to July, and depending on when they are sown, they can be harvested until October. However, they don't like frost very much. 


It's difficult to name the best varieties. Aarhus University previously conducted a study that showed that the old variety Karlek clearly gave the best yield, remained healthy and didn't tend to become woody like the more modern varieties. I haven't been able to find it online, but maybe you are lucky to buy seeds somewhere. Otherwise, you'll have to try your luck with another variety. The modern varieties are not bad, but they don't yield quite as much because cracked plants and those with scab are sorted out. 

How to prepare turnip cabbage

Turnip cabbage can be enjoyed raw with a delicious savoury marinade, or in a fresh salad with, for example, fennel, apples. You can also cut the turnip cabbage into paper-thin slices and enjoy it seasoned with an oil, vinegar and honey dressing. Alternatively, the cabbage can be stewed, blanched, or boiled together with potatoes for a delicious winter mash. Or you can pickle the cabbage and serve it warm as a side dish, for example in combination with fish.

(Source: Årstiderne.com) 

Creamy turnip cabbage for 4 people 

  • Add the cabbage to a pot with boiling water and let it simmer over low heat with the lid on for about 5 minutes. 
  • Add whole milk and bring the mixture to boil. 
  • Mix butter and flour together to form a butter ball using a fork. 
  • Add the butter ball to the pot and simmer the creamy cabbage over low heat without a lid for about 5 minutes. 
  • Add parsley and season with salt and pepper. 

(The recipe is from Arla.dk) 

Om Lars Lund

Lars Lund
Danish horticulturist and journalist
Lars Lund has for many years engaged in the garden and greenhouse. Lars has published many books about greenhouses, and he has participated in many Danish horticultural TV shows. He is a walking garden encyclopaedia, and he has answers for most basic cultivation questions – also the more ambitious ones.  

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