Bare-root vegetables: growing tips

Sunset, Jan, 1999

Artichoke

Artichokes need mild winters and summers. They thrive in coastal gardens, particularly in central California - the epicenter of Western artichoke culture - where they grow into leafy mounds 5 feet tall. (In hot interior climates, they may grow only half that tall.)

They're propagated in winter or spring from root divisions; these are sold bare-root or, more often, potted up.

WHERE IT GROWS: A dependable perennial crop in Sunset climate zones 8, 9, and 14 through 24. Elsewhere, plant in spring when divisions become available at nurseries, and hope for the best. In the desert, grow plants in filtered light, out of direct afternoon sun.

PLANTING AND CARE: Space divisions 4 to 6 feet apart, with growth buds or shoots just above the soil surface. Bait for snails and slugs.

Mulch plants well to keep roots cool and moist in summer. Feed in spring or fall; water whenever the soil surface beneath the mulch dries out. In cold-winter climates, cut plants down to the ground after harvest in fall (unnecessary in mild-winter climates). Replace them every five years or so.

HARVESTING: Pick buds when they're small by cutting stalks 2 to 3 inches below buds with a knife. You can eat buds whole when they're smaller than an apricot. As buds mature and grow, there's more to eat, but also more to discard, as scales become hard and stringy.

Along the central California coast, plants can produce two crops a year. After you harvest the first buds in June, cut the plants down almost to the ground, and they will regrow, giving you a second harvest in autumn. Elsewhere, expect one crop, usually in early summer.

BEST VARIETIES: 'Green Globe' is the standard California artichoke, but there are hardy varieties like 'Imperial Star'. The purple, egg-size 'Violetto' is also becoming popular.

Asparagus

Buy bare-root crowns (clumps of roots and dormant buds). Asparagus plants are either male or female. Look for all-male varieties: instead of wasting energy producing seeds, males grow bigger spears (and more of them) and spare you the task of weeding out inferior seedlings. If you grow a variety that contains both male and female plants, cut the seed capsules off the females to eliminate seedlings later.

Plants take two to three years to come into full production.

WHERE IT GROWS: All zones.

PLANTING AND CARE: Dig a trench about 6 inches deep in well-amended soil. Set the crowns in the trench at 15-inch intervals, and cover them with 2 inches of soil. As the spears grow, add 2 inches of soil for every 2 inches of growth, barely covering the tips of the new spears. Keep doing this until the soil is mounded 4 inches above ground level.

At planting time, add 1 pound of 5-10-10 fertilizer per 12 1/2 feet of row. In following years, mix a high-nitrogen fertilizer into the soil just before new spears appear, then again after harvest.

HARVESTING: To strengthen their roots and ensure good harvests in the years to come, let asparagus shoots develop into ferns the first season. Wait until the second spring to harvest a few spears. From the third spring onward, you can harvest spears over a two-month period, or until new spears start to become thinner. When they're just 3/8 inch in diameter, stop picking.

Harvest by snapping or cutting 5- to 10-inch spears off at ground level. In fall in mild regions, cut ferns to the ground. In snowy-winter areas, leave them until late winter so the ferns can help hold the snow mulch in place and protect the roots below from freezing (they can tolerate temperatures to -40 [degrees] with no damage).

BEST VARIETIES: 'UC 157' (about 70 percent male); 'Jersey Giant', 'Jersey King', and 'Jersey Knight' (all male). Purple varieties like 'Purple Passion' are also gaining popularity for flavor and color.

Horseradish

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 here. 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.