Guide to Growing Kohlrabi
Like cabbage and Brussels sprouts, kohlrabi belongs to the brassicas family, making it a hearty addition to any garden.
Kohlrabi produce striking stems and leaves and would make an attractive addition to an ornamental display. Their swollen stems have a delicious nutty flavor, like a cross between celery and cabbage. Read below to find out how to make these colorful crops work in your garden design.
How to Grow
Kohlrabi are tolerant plants and will grow well in most garden soils, sandy or heavy, but will crop best in rich soil, improved with plenty of organic matter. When planting, avoid beds where traditional brassicas have been grown in the last three years to avoid clubroot; kohlrabi is a member of the brassica family.
For early crops, sow seeds under cover in modules, and plant outside in the late spring after all frost has passed. Sow outdoors in the late spring to early summer when the soil has warmed up. Cold soil may cause plants to bolt (run to seed and spoil). Sow in rows 12 inches (3 0cm) apart, 3/4-inch (2 cm) deep and 9 inches (23 cm) apart. Kohlrabi is fast growing, ready to pick when the stems reach golf-ball size, around seven to eight weeks after sowing. Crops left to grow larger become tough and tasteless. For a constant supply throughout the season, sow in repeated batches every two weeks throughout the spring and summer. Water plants regularly to prevent roots from becoming woody; they won’t require additional feeding.
Kohlrabi can be grown successfully in containers, and repeated crops can be planted in the same compost all season; it may need refreshing after each harvest and should be discarded in the fall. Position in a sunny spot, and keep plants well watered. Feed container-grown plants every other week using a balanced liquid feed. As a bonus crop, when harvesting the mature stems also pick the young tender leaves, and use them as summer greens.
Types and Varieties of Kohlrabi
- Purple varieties are slower to mature and hardier. Sow them later than white-skinned varieties for late summer and fall crops. Try ‘Azure Star’, ‘Blusta’, ‘Kolibri’ F1 and ‘Purple Danube’ F1 varieties.
- White varieties are the best choice for quick harvests and can be sown as “catch crops” while other vegetables become established. Try ‘Korfu’, ‘Lanro’, ‘Logo’, ‘Olivia’ F1, ‘Rapidstar’ and ‘Superschmelze’ varieties.
Watch Out for These Pests and Diseases
Clubroot affects all brassicas, including kohlrabi, stunting the roots and reducing the crop. Avoid this problem by planting kohlrabi in spots where brassicas have not been grown in the last three years.
Leaf-eating pests, such as caterpillars and flea beetle, can also attack kohlrabi plants, but since the crop is grown for its stems, minor leaf damage can be tolerated.