More condiment than spice or herb, horseradish is easy to grow; it has adapted well to the West from its native southeastern Europe. In the garden, this perennial forms a large clump of long, narrow, ragged-edged green leaves that feel like chard. It does best in rich, moist soil in cool regions. You peel and grate its white roots to make the spicy-hot sauce described below.
WHERE IT GROWS: All zones except the low desert (zone 13).
PLANTING, CARE: Plant the fleshy roots in the ground 2 to 3 feet apart, or in a horseradish container like the one pictured below. Either way, horseradish that's rooted in spring will be ready to harvest after you cut the tops off in fall; it yields about 1 pound of roots per plant. Unless your soil is poor, horseradish needs no fertilizing, since nitrogen encourages forked roots. Horseradish does need regular water; grown drier, it produces smaller, more pungent roots.
HARVESTING: For horseradish in the ground, you can harvest either the lateral roots, leaving the center taproot to renew the plant, or harvest the main taproot itself.
If you're going to try the second method, carefully remove the soil from around the top two-thirds of the root when the plant is a foot tall. Nip off the lateral roots you've exposed, then gently repack the soil around the taproot. Repeat the process six weeks later. This directs the plant's energy into the main taproot, allowing it to grow fat for fall harvest; it's far easier to peel and prepare one large root than several small ones. After you've dug the taproot, replant one of the lateral roots growing off the bottom of the taproot to make next year's plant. Don't leave other bits of root in the soil, since they too will grow new plants and you'll have a hard-to-harvest colony instead of a single plant.
BEST VARIETIES: There are few named varieties of horseradish.
HORSERADISH SAUCE: Put 1 1/2 cups peeled and diced horseradish root in a food processor. Whirl it with 1 small peeled, diced turnip, 1 teaspoon salt, and 1/2 teaspoon sugar; slowly pour in 1 cup white vinegar. Yield: 3 cups prepared horseradish, which keeps about three months in the refrigerator.