How to Grow and Cook Kohlrabi and Rosemary

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Kohlrabi and rosemary pair wonderfully, and they're readily available as fresh crops through colder days.
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Kohlrabi yield edible leaves, and the crispy orbs are excellent winter keepers.

Many people have never tasted alien-looking kohlrabi, but when they do, they find the crisp texture a nice surprise. Though related to cabbages, turnips and broccoli — kohlrabi translates from German to “cabbage turnip” — kohlrabi is milder than those brassicas. I like to spark up its pleasant, distinctive flavor with an assertive herb. During winter months, when I cook my stash of kohlrabi, the herb I choose is often the rosemary grown in a pot that I’ve brought indoors. Kohlrabi and rosemary pair wonderfully, and they’re readily available as fresh crops through colder days.

What Is Kohlrabi?

Kohlrabi is usually considered a root vegetable, although technically its round globes are enlarged stem bases. Unlike true root vegetables, such as carrots and parsnips, kohlrabi doesn’t grow underground.

A kohlrabi “root” perches on the soil surface, sustained by a fibrous system of true roots below ground. It’s an odd-looking, smooth-skinned orb with stiff stalks protruding from various points on its surface, like antennas pointing to the sky. The stalks on the sides bear large, dark green leaves — similar to collards — with new, smaller foliage sprouting from the top. Kohlrabi leaves are edible. So are the stalks, but, in my view, they’re too tough to be worth the trouble of peeling and cooking.

Similar to its cabbage-family relatives, kohlrabi likes fertile soil with plenty of organic matter, and does best in cool weather. You could plant an early crop of baby kohlrabi for a late spring treat, but if you have to choose only one season, a fall crop makes more sense. We sow kohlrabi seed indoors in midsummer, and, as with most brassicas, set it out in the garden when the seedlings are about 3 weeks old. Then, we leave it in the ground until a hard frost is predicted. To harvest, we cut the orb at the base with loppers — the tissue there is too tough for a knife.

Kohlrabi’s globes act as the plant’s storage organs, just as carrots’ roots do. We’ve found that kohlrabi keeps all winter when stored in the root cellar. If you don’t have a cellar, use a frost-free outbuilding, a spare fridge or a cool room. Kohlrabi leaves will keep for at least a week if refrigerated.

Kohlrabi comes in pale green and bright purple hues. Varieties range from small (no bigger than 2 to 3 inches in diameter) to giant (the size of bowling balls). For a long time, I grew only the little ones, picking them young before they could become woody. Then, we started growing great big kohlrabi to feed to our laying hens in winter. The chickens adored them, and, amazingly, we liked them too. The large kohlrabi — maybe not the biggest ones, but those about 4 to 8 inches across — even became a hot item with our customers at the winter farmers market.

Good kohlrabi varieties include the large, purple ‘Kolibri,’ and the green ‘Gigante’ and ‘Kossack,’ all of which scored well in trials at Cornell University, as did the smaller varieties ‘Winner’ and ‘Grand Duke.’ Breeders have mostly selected for tenderness. There’s no compelling reason to choose purple kohlrabi over green ones, as the flesh inside both is the same white color. But the ribs of purple kohlrabi leaves do keep some of their color when cooked, and the roots look beautiful in the garden — or in a bowl on the kitchen table.

How to Cook Kohlrabi

Before cooking kohlrabi, slice off the tough base at the bottom and peel off all the fibrous skin. Inside, you’ll find crisp, white flesh, tinted green just under the skin.

Kohlrabi can do anything potatoes can do, sometimes better. Sliced or cubed and then cooked, kohlrabi holds its shape without turning to mush. Try substituting kohlrabi for potatoes in potato salad, scalloped potatoes or potato pancakes, and you’ll see what I mean. I’m not much of a deep-fryer, but I bet kohlrabi would make fine french fries.

Kohlrabi is good baked in a gratin, added to soups and stews, or tossed in olive oil and garlic and then roasted — in a medley of other root vegetables or by itself. I love it puréed with a little cream and great handfuls of parsley to give it extra flavor and a bright green color. In Germany, where kohlrabi is a popular vegetable, it’s sometimes hollowed out and filled with a meat or bread stuffing — a good reason to grow roots that are somewhat on the large side, even if you don’t have chickens.

The plant’s green tops, especially those on large, older kohlrabi, can be a little bitter and strong-tasting if steamed or sautéed — normally my favorite ways to cook greens. Kohlrabi greens turn mild when simmered, blanched in cold water, drained and then sautéed. Aside from being nutritious, their best virtue is that they keep their shape better than other greens, and don’t shrivel when cooked. This means you can cut them into ribbons, as recommended in the soup recipe on Page 18, and they will retain their shape as they float in the broth.

In addition to cooking kohlrabi, you can explore ways of eating it raw. Like turnips, kohlrabi can be eaten uncooked when young, whether grated or thinly sliced. It turns up in green salads, and you may often encounter recipes for kohlrabi coleslaw combined with other ingredients, such as sliced or grated apples. Try it as a dipper for hummus alongside the more standard carrots and pita bread.

Growing Rosemary

You can only grow rosemary outdoors through winter if you live in a mild climate. The herb is native to the Mediterranean, and prefers that region’s sun and heat. Growing rosemary indoors is easy, but the plant requires regular moisture — just be sure to let the soil dry out completely between waterings. Feed rosemary a liquid fertilizer made from seaweed or fish to encourage new growth that will be lovely to cook with, soft enough to use in a winter salad, and perfect to stuff under the skin of a roasting chicken or scatter over a roasting root-veggie mix. As days start to lengthen in late winter, even more new growth will appear, making rosemary a reliable herald of spring.

Want some fresh ideas for how to eat kohlrabi and pair it with savory rosemary? Try these delicious, easy kohlrabi recipes:

Kohlrabi ‘Chips’ Recipe with Horseradish Cream
Kohlrabi Soup Recipe with Asian Flavors
Kohlrabi Gratin Recipe with Cheddar

Grow On!

There’s much more to learn about growing kohlrabi and its bold brassica buddies in our Crops at a Glance Guide. Find advice on how to grow rosemary in your garden or a pot.

Barbara Damrosch cooks kohlrabi and tends rosemary with her husband, Eliot Coleman, at Four Season Farm in Maine. She’s the author of The Garden Primer and, with Coleman, The Four Season Farm Gardener’s Cookbook.

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