Kohlrabi: I Grow An Oddball
By Nancy Pierson Farris, South Carolina
Kohlrabi: the oddball among vegetables I grow in spring. The word means turnip-cabbage. Like a turnip, kohlrabi produces an edible bulb. Unlike a turnip, kohlrabi bulbs grow above ground. Like cabbage, kohlrabi leaves attract cabbage butterflies; unlike cabbage, kohlrabi leaves grow, not from a root, but from a bulb.
Like other cole crops, kohlrabi grows best in cool weather; early spring or in the fall. In a normal year, I can grow kohlrabi in the garden about a month before Easter. (Usually our last cold snap occurs Easter week.)
This year, due to unpredictable winter weather, I started a few kohlrabi, along with other coles, in a flat in my cool greenhouse.
I use flats which my husband, Don, built. For the sides, he used 1 x 4s and the bottoms are counter-top material left over from a kitchen remodel. Don used a quarter-inch drill bit to make drainage holes at five-inch intervals in the bottom of each flat.
I begin by spreading two inches of good potting soil in each flat, then I add an inch of sterile soil or vermiculite. Thus, I sow seeds in a sterile medium, and if unsettled weather forces me to leave seedlings in the flat for an extra week or two, the potting soil underneath provides nutrients and support for the developing root systems.
About eight weeks before the last spring frost, I sow seeds—thinly so seedlings won’t get crowded as they grow—and cover lightly with sterile medium. I lay a piece of glass over the top or wrap the flat in plastic, to conserve moisture.
When seeds sprout (about a week to 10 days), I remove the cover and set the flat under a shop light in the greenhouse. I use one white and one regular tube (white is cooler, but costlier). I adjust the chains holding the light fixture so that plants are four to six inches below the tubes.
I water often enough to keep soil moist but not soggy. As seedlings grow and weather warms, I may water twice a day. Once a week, I add soluble fertilizer to the watering can. I use fish emulsion (the odor makes my cat crazy, but the fertilizer promotes healthy foliar growth).
About three weeks after I sow the flat, Don prepares the garden row, using a rotary tiller. One evening, or on a cloudy day, we move the flat to the garden row. I lift a clump of seedlings from the flat and gently separate them. Since stems are fragile, I handle seedlings by leaves or roots, and set plants at two-inch spacing. Then, I lay a soaker hose along the row and water for a few minutes to settle the soil around the roots. Thereafter, I water for a few minutes each day to keep soil moist.
About a week later, Don prepares another 10 feet of row. Since our soil tends toward acidity, I check with my trusty pH meter. If it reads below 5, we add a bit of dolomitic lime or wood ash to the compost we place in the furrow. We cover that with a couple of inches of soil, then sow the kohlrabi seeds, and cover lightly. We keep the soil moist until seeds sprout, about a week to 10 days later. This year, I interplanted nasturtiums with cole crops—this tasty, edible flower may repel cabbage butterflies.
Don sprays all cole crops weekly with bacillus thurengiensis to reduce cabbage butterfly populations.
I have grown the White Vienna, which produces three-inch bulbs in about six weeks. This year, I started with Express Forcer (Parks Seeds), which matures in just over five weeks, and tolerates frost well. I started kohlrabi in flats during the winter storms of February and began harvesting small bulbs in late March. For a continued harvest, I planted Purple Vienna and Kongo Hybrid, (both from Shumway Seeds). The former has purple skin and the Kongo will make bulbs up to six inches across. Both varieties require 60 days to full maturity. Sown in March, these produced through May and June.
By July, cole crops are becoming tough and bitter, and the cabbage butterflies are making plans for a summer festival in my garden. It is time to harvest kohlrabi and clear the row for okra or black-eyed peas.
Kohlrabi has a flavor like a mild turnip with just a hint of apple. Small bulbs need no peeling and can be sliced to add a nice crunch to spring salads. I add slices or wedges of larger bulbs to salads or vegetable trays. I also shred the larger bulbs into coleslaw or carrot-apple salad.
I make a stir-fry using sliced kohlrabi added to a skillet in which I have gently cooked onions in a bit of olive oil.
Kohlrabi is neither turnip nor cabbage—it looks like an oddball and has a unique flavor. I enjoy growing it, not only for the taste it adds to spring salads, but for the conversation piece it can become when neighbors see it in my garden!
Originally published in the May/June 2014 issue of Countryside & Small Stock Journal.