“Kohlrabi’s unique growth habit makes the garden feel like a moon landing site.”
— Edward C. Smith, “The Vegetable Gardener’s Bible,” 2011
I’ve decided to initiate an intermittent series on weird garden plants, starting with the alien look-alike vegetable, kohlrabi.
I had never seen kohlrabi until I moved to Southern Oregon six years ago and someone gave me some starts. Kohlrabi is supposedly more commonly eaten in the South, but my dad and I never grew it in our raised beds in Central Florida. Collards and mustard greens, yes; kohlrabi, no.
Yet, I learned that kohlrabi is moderately easy to grow here, plus it doesn’t take up much garden space and offers lots of nutrition. Some gardeners say kohlrabi is a bit like zucchini — it’s easy to grow too much of it all at once. Of course, you can always share extra kohlrabi with baffled neighbors. Also, some cultivars, such as Kossack, store for a long time.
Kohlrabi descended from the wild cabbage; in fact, the name comes from the German words “kohl” for cabbage and “rabi” for “turnip,” the latter in reference to the bulbous bottom portion of the plant’s stem (often mistaken for a root). Kohlrabi is a member of the Brassica family that also includes broccoli, cauliflower and kale.
Different varieties have white, light green or purple globes with rubbery skin, ivory flesh and large leafy tops. The globes and leaves are connected by fleshy stem parts that look like appendages. All parts of the plant are edible, although the skin is usually pared off before eating. Some gardeners say the purple globes taste the sweetest.
The OSU Extension Service recommends several varieties for our area: Kolibri, Express Forcer, Early White, Early Purple, Vienna, Kongo and Eder. Gardeners also like the Winner hybrid. If you want to supersize, Baker Creek Heirloom Seeds offers Superschmeltz, a gigantic light-green kohlrabi.
Kohlrabi is a cool-weather crop, so direct seed in the garden during March and April, and then again in September and October. Kohlrabi likes rich, consistently moist soil and full sun, although it will tolerate partial shade, especially from the hot late-afternoon sun. In fact, one of the challenges of growing kohlrabi is ensuring that the soil doesn’t become too hot or dry out. Using floating row cover as needed for significant temperature shifts will help to address this problem.
Kohlrabi is a heavy feeder, so add compost with lots of organic matter and provide an extra boost of nutrients with a balanced fertilizer every 3-4 weeks. Be on the lookout for the usual culprits when it comes to Brassica crops — cabbage maggots, cutworms, beetles and aphids.
Depending on the variety, kohlrabi will be ready to harvest in 38-48 days. Some cultivars, such as Eder, mature earlier. Pick when the bulbs are 1½ to 2 inches in diameter; the bulbs should be firm, not spongy. Over-ripened kohlrabi becomes woody in texture and taste. Kohlrabi will keep in the refrigerator for a few weeks, but I try to pick close to the time I’ll be eating them for the freshest taste.
Kohlrabi is a fun crop to grow because of its unusual appearance. To some people, like garden writer Edward C. Smith, kohlrabi looks like lunar spacecraft; others say the round globes and top leaves remind them of hot-air balloons. I think of doll heads with crazy hair. Why not grow some kohlrabi to see how it sparks your imagination?
— Rhonda Nowak is a Rogue Valley gardener, teacher and writer. Email her at firstname.lastname@example.org.