Kohlrabi is an unusual vegetable, sure to attract attention at your market booth, or be a discussion piece in CSA bags. It is tender with a flavor between a cabbage and a turnip. And it’s a tasty crunchy vegetable that’s easy to grow and doesn’t wilt as soon as you harvest it. It can be eaten raw (sliced or grated) or cooked. The kind most commonly grown is a pale green or purple globe (the swollen stem of the plant) with long-stemmed leaves. It stores well, offering flexibility about when it is sold, which is always an advantage for growers. In addition, the leaves are edible.

Varieties
There are two main types of kohlrabi, the small round smooth ones such as the Viennas (‘Early White Vienna’ and ‘Early Purple Vienna’), and the somewhat lumpen giant winter storage types, such as Gigante.

We like the open pollinated Viennas, (58 days from direct seeding, about 40 days from transplanting), and also the purple hybrid Kolibri (45 days from direct seeding, about 30 days from transplanting for a small globe), which is more expensive, but very beautiful, quick growing, and very uniform. Purple kohlrabi are white on the inside. You’ll notice that the purple ones grow slower than the white (green) ones. A mixture of the two colors looks very attractive, and they’re much the same under the skin, so our strategy is to grow 25-35% purple, and mix them in. Some people consider the purple ones to be more flavorful than the white ones. A 4 g packet contains about 1275 seeds, and sows 135’. 5,500-9,000 (avg. 6500) seeds/oz..

The open-pollinated Gigante Kohlrabi (130 days from sowing, or 110 days from transplanting) reportedly does not get woody even when it grows enormous. I confess that although we’ve sown this we’ve never really started early enough for its required 130 days/4 months of growth. To do it justice here, we should probably count back from a late October harvest, and sow in June. Gigante is resistant to root maggots.

Superschmelz Kohlrabi is a 60 day (from transplanting) variety recommended for summer sowing for fall harvest.. Superschmelz produces 8-10 inch bulbs, which remain tender, and an attractive globe shape.

Crop Requirements
Conditions for growing kohlrabi are much the same as for other brassicas. It does best in cool weather. It is a fairly heavy feeder, and for best growth it needs a regular water supply. It is very hardy if grown in fertile well-drained soil. In Virginia, kohlrabi, like other brassicas, can be grown in spring or fall. In cooler climates, kohlrabi can be grown anytime during the growing season. According to ATTRA’s Companion Planting: Basic Concepts & Resources, Kohlrabi is traditionally seen as not a good companion plant for Pole Beans.

Sowing and transplanting
In spring, direct sow 4-6 weeks before the last frost, 0.25” deep, 1” apart. Or for an earlier crop, start transplants from 11 weeks before the last frost date to 2 weeks after, and set them out when 6-8 weeks old. We start ours as early as possible, around Feb. 8 (11 weeks before our last frost date of 30 April), and set them out at 6 weeks old (mid March), covered with row cover for a few weeks. We space ours 8” apart in the row, with 9-10” between rows (4 rows in a 48” wide bed). Planting them alongside turnips works well in terms of timing. If direct sowing, thin to 5” apart initially, then harvest every other one when 2” or more in diameter. For continuous cropping, make sowings every two weeks.

In the fall, count back 85 days from the first frost date, and direct sow then. Or sow in a nursery bed, or cell packs, and transplant at 3-4 weeks of age. We transplant around Aug. 11 from sowings made July 5-12. Later sowings (up till early September) would also work for the fast maturing varieties.

Pests and diseases
Brassica pests seem less interested in kohlrabi than in other brassicas, and as the leaves are not the part eaten by humans, there is scope for allowing a certain number of leaf-eating pests, while still having an attractive crop, and a high enough yield.

Trials at Southern Exposure Seeds have shown Purple Vienna to be slightly more resistant to the cabbage worm than White Vienna. Purple varieties also seem less susceptible to cracking of the bulb.

Harvest
Harvest when the kohlrabi are 2 to 3 inches in diameter or even up to softball size. If left growing for too long the swollen stem becomes woody. Cut them from the ground with a sturdy knife. The base of the globe can be quite fibrous, so cut either the wiry root just below the soil surface, or cut higher, leaving a small disc of the globe behind, attached to the root. Snip or lop off the leaves, perhaps leaving a small top-knot if the kohlrabi will be sold immediately. We harvest in spring from around May 10 to June 30, and in the fall from Oct. 20 to Nov. 15.

Post-harvest
Kohlrabi stores well in perforated plastic bags in a walk-in cooler. In a plentiful year, we have had kohlrabi as a winter storage vegetable into early spring.

Cooking
Enthusiasts will eat a kohlrabi out of hand like an apple, enjoying the crunchiness. Thin “coin” slices are good with dips, and the grated vegetables make a nice salad. Cooking is simple – the globes can be diced or sliced and steamed, or added to a stir-fry.

Sources for seed
•Southern Exposure Seeds, VA: www.southernexposure.com 540-894-9480
•Fedco Seeds, ME: www.fedcoseeds.com/
•Territorial Seeds, OR: www.territorialseed.com 800 626 0866.
•Johnny’s Selected Seeds, ME: www.johnnyseeds.com/ 877 564 6697

Other resources
ATTRA has several useful publications. See Cole Crops and Other Brassicas: Organic Production http://attra.ncat.org/attra-pub/cole.html

For the history of kohlrabi, see Oregon State University, Corvallis, Food Resource http://food.oregonstate.edu/faq/uffva/kohlrabi2.html

Pam Dawling is the garden manager at Twin Oaks Community in Virginia. The gardens provide the 100 residents with nearly all their fresh and preserved fruits and vegetables. She can be contacted at pam@twinoaks.org.