Do you know what kohlrabi is? When you are going to produce aisle, you probably missed it. The vegetable is, after all, looks unfamiliar. Kohlrabi means “cabbage turnip” in German, which gives a clue about its origin and taste. That’s right. Kohlrabi is a member of the cabbage family, together with broccoli, cabbage, kale, and mustard.
Since you are here, you are probably interested in growing kohlrabi on your own. Well, that’s exactly what we are going to tell you. We will tell you how to grow kohlrabi from start to finish. From growing seed to harvesting and storing. Before we get there, however, let’s start with a brief introduction to kohlrabi and cultivars to grow.
- 1 About Kohlrabi
- 2 Cultivars to Grow
- 3 How to Grow Kohlrabi: Planting the Seed
- 4 How to Grow Kohlrabi: Caring
- 5 How to Grow Kohlrabi: Harvesting and Storing
- 6 How to Grow Kohlrabi: Common Pests and Diseases
- 7 Growing Kohlrabi Tips
Brassica oleracea, better known as kohlrabi or German turnip, is a member of the cabbage family. It is a cool-weather crop, related to broccoli, cabbage, kale, and mustard. Although often grown as annuals, kohlrabi is actually a biennial. The part that is commonly harvested is the bulb, although some gardeners do harvest its leaves.
Being a cool-weather crop, kohlrabi can withstand cool temperature, even a frost, better that it can hot temperature. If the temperature is too hot for the plant, it will go bolt. Because of this, kohlrabi should be planted before the temperature is over 75 degrees Fahrenheit. It takes about 45 to 60 days for Kohlrabi to reach maturity.
There are two types of kohlrabi: purple and green. The green one is the most common. You probably have seen it in stores. The purple one has a beautiful color. Both types are edible. Since the way you grow these varieties is the same, you can follow our how to grow kohlrabi guide here regardless of which variety you plant.
Cultivars to Grow
Before we tell you how to grow kohlrabi, you should know about the cultivars first. Among the most popular kohlrabi cultivars are Gigantes, Purple Vienna, Grand Duke, and Early White Vienna. Each cultivar has different colors, sizes, shapes, and time to reach maturity. We describe each cultivar briefly below.
If you want to grow kohlrabi that yields large a large bulb, consider Giganti cultivar. True to its name, it produces not only a large but also tasty bulb. This cultivar is disease resistant and its harvest can be stored for a long time.
2. Purple Vienna
Want to grow kohlrabi and decorate your garden? In that case, Purple Vienna fits you. This cultivar grows beautiful leaves, making it quite a decorative addition to any garden.
Some cultivars reach maturity faster than others. Grand Duke is one of them. This cultivar needs about 50 days to reach maturity. Bonus: it is the only kohlrabi that receives an All-America Selections Winners distinction.
4. Early White Vienna
Our how to grow kohlrabi guide here is also for gardeners who have limited space available to grow kohlrabi. If you can’t afford a large space to grow kohlrabi, Early White Vienna is for you. It is a ‘dwarf’ variety that doesn’t take too much space. It is also productive as it can stay in the garden longer yet doesn’t bolt.
Knowing how to grow kohlrabi is one thing. Knowing which cultivar to grow is another. So, which one is the best cultivar for you to grow? That depends on what you want. For example, if you want large, tasty yields, choose Gigantes. Likewise, if you want your garden to be a bit more decorative, choose Purple Vienna. And so on.
How to Grow Kohlrabi: Planting the Seed
1. Preparing the planting site
- The first thing in our how to grow kohlrabi guide is preparing the planting site. Kohlrabi is a cool-weather crop but it needs full sun exposure. As such, designate a spot with full sun exposure.
- As for the soil, kohlrabi grows best in rich, well-drained soil with a pH level between 5.5 and 6.8. To help the seeds grow, you can also work aged compost into the planting site prior to planting.
2. When to Plant
- Since kohlrabi is a cool-weather crop, you need to provide it with time to grow and reach maturity before the temperature rises to over 75 degrees Fahrenheit. In general, it takes about 45 to 60 days for kohlrabi to reach maturity. That means the best time to plant seeds is between 3 and 4 weeks before the last spring frost.
- If you live in a region with warm winters, sow the seeds in late summer. This way, you can have a winter harvest. Don’t worry about the frost. Remember, it is a cool-weather crop so it can withstand a mild frost. If anything, a frost can make the bulb tastier.
- If you live in a region with cold winters, sow the seeds in summer. Sowing during this time should you an early autumn harvest.
The next section in our how to grow kohlrabi guide is planting. Here’s how to do it:
- Sow the seed in the soil about 1/2 inch deep. Give the seeds 1-inch space in-between.
- After the seedlings grow, thin the successful ones so they are 5 to 8 inches apart. The rows should have 18 to 24 spaces from one another.
- If you have the space, you can transplant the thinned seedlings for more crops.
Note: we don’t include how to grow kohlrabi in containers because kohlrabi is a large plant and doesn’t sit well with containers.
How to Grow Kohlrabi: Caring
A how to grow kohlrabi guide is not complete if it doesn’t tell you how to care for kohlrabi. Other than the need for full sun and cool temperatures, kohlrabi is not that demanding. That being said, you still need to take care of it for the best growth and yields. We divide this section into several parts and explain each.
Like Brussels sprouts and broccoli, kohlrabi likes cool weather. By the time the temperature of summer comes, kohlrabi has finished growing. This is the reason why you need to provide the plants enough time to grow before summer arrives. Otherwise, it will produce flowers or go bolt due to the warm weather.
A kohlrabi plant cannot grow to its full potential if it doesn’t receive enough light. So, make sure that every kohlrabi plant in the garden can bask in the sunlight.
There is something unique about kohlrabi. On one hand, it isn’t a root vegetable. On the other, it likes similar growing conditions that root vegetables like radishes or carrots like. It likes loam, rich, and moist soil. If you want bulbs with tender flesh, growing kohlrabi in raised beds can help.
You don’t know how to grow kohlrabi if you don’t know how to water the kohlrabi properly. For best growth, keep your kohlrabi plants well-watered. Keep the soil moist at all times. If kohlrabi doesn’t receive enough water, the bulb will become woody. Want to give your plants a nutrient boost? Use compost tea to water it.
Although kohlrabi is easy to grow, as this how to grow kohlrabi has shown you, it is a heavy feeder. That means if you want the best yields possible, you need to either use amendments to enrich the soil or add chemical fertilizers. Of the two, the former is the better option.
Giving kohlrabi a good start is not a bad idea, either. You can give your kohlrabi plants a good start by adding manure during planting. For the rest of the growing season, apply compost to side-dress the rows until harvest time. This should be enough to feed our heavy feeder.
How to Grow Kohlrabi: Harvesting and Storing
The next section in this how to grow kohlrabi guide is for harvesting and storing kohlrabi. Knowing how to harvest and store cabbage turnip really goes a long way. This is especially true if you are planning to grow kohlrabi for the long term. Let’s start with how to harvest the cabbage turnip first.
- It takes about 45 to 60 days for kohlrabi to grow from seed to harvest. How long it will take to mature depends on the cultivar.
- You cannot determine when to harvest kohlrabi by the color of the bulb. You can, however, determine when to harvest by the size of the bulb.
- While there is no exact date when to harvest kohlrabi, you can start harvesting once the first stem grows about 2 to 3 inches in diameter. Some gardeners harvest kohlrabi earlier, when the stem is 1 inch in diameter. That’s up to you. Younger bulbs tend to be more flavorful than older ones.
- Harvesting kohlrabi can be done in multiple ways, depending on which parts you want to harvest. If you just want to harvest the bulb right there and then, pull the entire plant. If you want to harvest the bulb and the leaves, cut the plant at the base and leave the roots in the ground.
- If you want continuous harvest, plant two or three weeks apart.
- A kohlrabi plant can be harvested continuously. The first harvest is when the stem is 1 inch in diameter. After the first harvest, it can still be harvested continuously until its stems grow to 2 to 3 inches in diameter, when the plant is too tough and too old.
- Kohlrabi can be frozen.
- You can store kohlrabi in the refrigerator and it will last about 1 week.
- For longer shelf life, store kohlrabi in a cold and moist place. This extends the shelf life to up to two months.
How to Grow Kohlrabi: Common Pests and Diseases
This how to grow kohlrabi isn’t complete if we don’t include common pests and diseases. So, here it is.
- Among the most common pests that attack kohlrabi are cabbage loopers, imported cabbage worms, and cutworms.
- To protect young plants from cutworm damage, place collars around their stems. Diatomaceous earth can also prevent cutworms from attacking the plant.
- Check the leaves regularly. If you find egg clusters on the undersides of the leaves, remove them immediately. Then, prepare a diluted soap solution and wash the affected plants with it.
- Cabbage worms can be handpicked to remove. You can also control cabbage worms by spraying them with Bacillus thuringiensis.
- Kohlrabi is vulnerable to diseases like downy mildew, clubroot, and cabbage yellows. These diseases are better prevented than cured. So, it is best to choose disease-resistant cultivars. In case your plants have any of these diseases, quickly dispose of and destroy any infected plants.
Growing Kohlrabi Tips
Let’s close our how to grow kohlrabi guide here with some growing tips. These are some useful tips to help you grow your own kohlrabi in the garden:
- The bulb of kohlrabi can become woody if the temperature is too hot. Mulching will help prevent that as it preserves moisture. Mulching also helps to prevent weeds as well.
- When you cultivate kohlrabi, be sure to do it carefully so as not to harm the shallow roots.
- When the plant is about 4 to 5 inches, mulch it with aged compost to help it grows.
- For best growth and yield, grow kohlrabi at the right time. Being a cool-weather crop, kohlrabi can withstand a mild frost. If anything, a frost makes the bulb taste better. Time the planting properly and avoid growing kohlrabi when the weather is hot.
- Because kohlrabi produces a large bulb, container gardening is not recommended. You can plant a kohlrabi plant in a container but only as a novelty, however.
- Planting other plants in the garden? That’s awesome! You can plant kohlrabi alongside onions, cucumbers, beets, and other Brassicas. Avoid planting kohlrabi near tomatoes, strawberries, bole beans, and near peppers.
- As this how to grow kohlrabi guide has shown, kohlrabi can be harvested in two ways: either by pulling the entire plant or by cutting the base and thus leaving the root intact. Whichever way you harvest your kohlrabi, make sure to do it carefully especially if you want to harvest again later.
Kohlrabi is easy to grow. It does, however, require caring. But now that you know how to grow kohlrabi, that shouldn’t be a problem. If you are growing kohlrabi for your family, make sure that you plant enough of them. 4 to 5 kohlrabi plants should be enough for a family member. Ready to try? Happy gardening!