All you need to know about asparagus
Asparagus makes a permanent and dependable crop. Choose a spot in the garden where the plants can stay for years ― along a sunny fence, for instance. The tall, feathery, graceful ferns are highly ornamental behind other vegetables. Tender spears are one of dinner's great luxuries; they're tasty when steamed whole and served with creamy hollandaise sauce.
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° 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.