The kohlrabi plant is a fast-growing and often overlooked treasure to grow in the vegetable garden. This brassica gem is rising in interest among gardeners and for a good reason. It produces its bulb, stems, and leaves above the ground, making it a fun crop watch mature. When planting and growing conditions are optimal, kohlrabi delivers sweet, crisp, juicy crops from garden to table.
Its previous lack of popularity is primarily because gardeners just didn’t know how easy and tasty this crop is to grow or perhaps still have never even heard of it. We will uncover the mystery of growing kohlrabi, providing planting and care tips so that you too can join the kohlrabi growing frenzy.
Ideal Soil Composition & pH for Growing Kohlrabi
Amend your garden soil with rich organic matter and well-decomposed compost before planting and growing kohlrabi. This delicious crop is somewhat forgiving about the soil it is planted in but grows optimally in nutrient-rich, well-draining soil with a pH range of about 6.0 to 6.8.
If you are unsure of your pH, you can obtain a soil test kit from your local garden center or bring a soil sample to your local extension office to have it tested.
Light & Temperature Requirements for Kohlrabi Plants
Kohlrabi plants thrive in full sun, where they will receive a minimum of 6 hours of direct sunlight per day. The ideal growing temperature for kohlrabi plants ranges from 40 to 75 degrees Fahrenheit. Grown in Zones 3-10, this crop is highly susceptible to heat. Too much heat and an insufficient water supply will result in the bulb turning fibrous, woody, and unpalatable.
How To Fertilize, Mulch, & Water Kohlrabi Plants
Water is essential to the success of kohlrabi plants. Kohlrabi prefers moist soil, so water regularly. Consequentially, if the plants have difficulty accessing adequate water, they will produce chemicals that have bitter, unappealing flavors. The bulbs of the plants will also become stringy and may crack open.
These brassica plants are also heavy feeders with shallow root systems, so they can benefit from a boost now and then. Side-dress plants with well-decomposed compost when plants are four to six weeks old. Mulch well with organic mulch around the plants to help regulate temperature and moisture levels and to further enrich the soil with nutrients.
How To Grow Kohlrabi
Kohlrabi can be started indoors in seed trays or have their seeds sown directly into the ground. Combining the practice of both methods can ensure the successful harvest of these vitamin-rich garden gems.
- Plant seeds indoors approximately 4 to 6 weeks before the final frost.
- Direct sow seeds directly in the garden bed in mid to late summer to grow a fall or early winter crop.
- Seeds should be planted at a depth of ¼ inch to ½ inch.
- Transplant seedlings when they are 3-4 weeks old and after the danger of frost has passed.
- Plant root balls of transplants so that they are level with the ground so that the bulbous portion will grow above the soil and not rot out.
Spacing Kohlrabi Plants in the Garden
Kohlrabi plants need room to grow. Plant seedlings 9-12 inches apart, in rows that are spaced 12 inches apart.
Where to Grow Kohlrabi
The kohlrabi plant can be grown in raised beds or in-ground in a backyard garden. It is best to rotate crops from year to year and not plant plants in the brassica family in the same location in subsequent years.
Kohlrabi can also be grown in containers, but with their moisture needs, they would need daily attention to ensure that the soil does not get too dry or too hot. This plant is not very forgiving of either condition.
Common Kohlrabi Plant Pests & Disease
- Slugs– Plant in raised beds to keep common ground pests like slugs off your leafy vegetables. Set out beer traps to trap and drown out pesky slugs.
- Cabbage Worms– Remove cabbage worms by hand and plant celery as a companion plant in the garden bed near kohlrabi. The aromatic leaves of the celery plant keep the white cabbage moth from infiltrating the garden bed. Use row covers to protect young plants from infestation.
- Aphids– Plant and grow nasturtiums nearby to lure away aphids and use a quick spray of a garden hose to knock destructive aphids off of plant leaves. Be sure to spray the undersides of leaves as well, where aphids often lurk.
- Downy Mildew– Provide adequate spacing between plants to ensure adequate airflow. Observe plant and remove diseased leaves immediately and dispose of them so that the fungus does not spread.
- Leaf Spot– Water plants from the base and water early in the morning so leaves have ample time to dry. Consider a drip irrigation hose around the base of plants.
Harvesting Kohlrabi Plants
Kohlrabi plants are easy to grow but can be somewhat tricky to harvest. Leaves, stems, and the bulbous base are all sought-after edibles and are harvested in different ways.
- Leaves can be harvested using the cut and come again method. Simply snip off leafy greens as you need them for consumption, starting with the outermost, more mature leaves. This allows the innermost leaves time to mature more fully.
- Stems should be at least an inch in diameter before snipping them off and harvesting them with pruning shears.
- The bulbous part of the plant should optimally be 3-4 inches in diameter when harvesting. Harvesting young bulbs results in a uniquely sweet flavor. Leaving the plant to grow a super large bulb can negatively impact the plant, causing the vegetable to be fibrous and woody. To harvest the plant’s base, pull the entire plant out of the soil and cut the roots from the bottom of the bulb. Leaves and stems can be cut off at the base and utilized, as well.
Recommended Kohlrabi Varieties
All Kohlrabi varieties produce edible stems, leaves, and bulbs that are produced above the ground. They are all quick producers in spring and fall gardens. Try these varieties in your home garden and enjoy them raw or steamed.
- ‘Purple Vienna’
- ‘Grand Duke’
- ‘White Vienna’