Kohlrabi
Other Common Names Include:
German turnip, stem turnip
Latin Name: Brassica oleracea var. gongylodes
Plant Family: Brassicaceae
Close Relatives: Cabbage, broccoli, cauliflower, Brussels sprouts
Uses and Markets: Culinary (e.g. traditional German/Northern European raw or cooked vegetable)
Production Life Cycle in Ontario
Annual
Hardiness Zone
N/A
Special Notes
Traditional varieties of kohlrabi are woody when larger than 5-10 cm. Larger varieties (e.g. ‘Kossak”) are now available that remain tender at a much larger size (15-20 cm).
Propagation method
Seed or transplant.
Greenhouse Seeding/Propagation Dates
March - April
Field Seeding Date:
April to mid-August
Field Transplanting Dates
April to late-August
In-row spacing
10 cm (traditional varieties) to 30 cm (large varieties).
Between row spacing
45 – 80 cm
Optimal Soil temperature at planting
>10°C
Fertility
The recommended nitrogen application rate for kohlrabi in Ontario is 80 kg/ha preplant and 30 kg/ha sidedress for mineral soils, and 70 kg/ha preplant with two subsequent sidedress applications of 30 kg/ha on muck soils. Ontario research has shown that large-stemmed varieties may require more nitrogen than traditional varieties. Click here for phosphorus and potassium application guidelines and for more information on specialty crop fertility.
Soil type
All soil types; will not survive in saturated soils.
Soil pH
6.0-7.5
Special requirements for growth habit
None
Optimal Temperature Range
18-25°C
Temperature sensitivity
Frost tolerant (some varieties bolt easily when exposed to temperatures close to freezing or a prolonged period below 10°C).
Irrigation requirements
Irrigation beneficial under normal Ontario conditions. More frequent irrigation is required on sandy soils. Fluctuating availability of soil moisture can lead to growth cracks.
Days to harvest
40 - 70 days (transplanted); 60 – 90 days (seeded); the low end of the range applies to traditional small varieties.
Specialized equipment
None
Harvest
Harvest Scheduling
Single harvest; successive plantings; multi-cropping possible.
Hand harvest or machine harvest
Hand harvest (clippers to cut below stem).
Quality parameters/grades
No established grades. Quality is determined by the market.
Additional Harvest Notes
Traditional kohlrabi should be harvested when no more than 5 cm in diameter, especially when grown in the spring or summer. Some markets prefer leaves attached and some with leaves trimmed off.
Post harvest
Special handling/curing
Harvest during cooler parts of the day to reduce moisture loss and cooling costs. Remove field heat as soon as possible after harvest.
Storage Conditions
Relative humidity (RH): 98-100%
Temperature: 0°C
Air Exchange: N/A
Duration: 2 weeks (with leaves attached); 2 to 3 months (leaves cut off).
Specific pests observed on this crop in Ontario (observations based on limited experience with this crop)
Insects and Invertebrates: Cabbage maggot (Delia radicum), flea beetles, swede midge (Contarinia nasturtii), diamondback moth larvae (Plutella xylostella), imported cabbage worm (Artogeia rapae), cabbage looper (Trichoplusia ni), tarnished plant bug (Lygus lineolaris), cutworms, leafminers (Liriomyza spp.), aphids, thrips, earwigs, slugs
Diseases: Club root (Plasmodiophora brassicae), downy mildew (Peronospora parasitica), Alternaria (black leaf spot), turnip mosaic virus (TuMV), bacterial soft rots (Erwinia cartovera, Pseudomonas spp.), black rot (Xanthomonas campestris), wirestem (Rhizoctonia solani), blackleg (Phoma lingam), fusarium wilt (cabbage yellows), damping off (Pythium, Rhizoctonia spp.), Bacterial leaf spot (Pseudomonas syringae)
Other: None
Other Potential Pests: The following pests have not been observed on this crop in Ontario. However, they are either significant concerns for closely related plants in Ontario, or are reported on this crop in other production areas. This is not a comprehensive list of all potential pests. Not all of these pests will necessarily survive Ontario’s climate, but could potentially survive in a protected environment (e.g. greenhouse, storage facility).
Insects and Invertebrates: None
Diseases: None
Other: None
*Indicates pests commonly mentioned as causing significant damage or economic loss to this crop in other regions.
Comments
To date the following pests have been the most significant in Ontario: Swede midge, cabbage maggot. Kohlrabi is the same species as cabbage, broccoli, and cauliflower, and therefore, shares all of the same pests as these crops. However, kohlrabi can tolerate higher damage from foliar pests, unless it is sold with the leaves intact. This crop is in Crop Group 5: Brassica (Cole) Leafy Vegetables and subgroup 5A: Head and Stem Brassica Subgroup. For more information on Crop Groups, refer to the Pest section. Always refer to product labels, and follow all directions specified on the label, before applying any pest control product. For more information, consult an OMAFRA specialist. For pest control products registered on this crop refer to OMAFRA Publication 838.
None
- Elford, E., Filotas, M., Todd, J., and S. Westerveld. 2009. Effect of nitrogen on yield and quality of ‘Kossak’ kohlrabi. OMAFRA Simcoe Resource Centre, unpublished.
- Howard, R.J., Garland, J.A. and W.L. Seaman. 1994. Diseases and pests of vegetable crops in Canada. The Canadian Phytopathological Society and The Entomological Society of Canada, Ottawa.
- Munro, D. B., and E. Small. 1997. Vegetables of Canada. NRC Research Press, Ottawa.
- Oregon State University. 2002. Commercial crop production guides – kohlrabi.
- University of California Division of Agriculture and Natural Resources. 1998. Publication 3346 Specialty and Minor Crops Handbook, Second Edition. University of California, Oakland.
