Text by Janet H. Sanchez
Illustrations by Elayne Sears
Reprinted from Horticulture

An Asparagus bed, once established, can be counted on to deliver dependable spring harvests for many years. This perennial planting also lends a soft, fern-like haze to the edge of a garden. The easiest way to start asparagus is to set out year-old dormant crowns in early to mid spring; these are sold at local nurseries or through mail-order suppliers. Plants you raise from seed will take an extra year to produce a harvest.
Choose a well-drained site in full sun or partial shade, keeping in mind that its placement will be permanent; don't put it in the way of yearly tilling. To determine the size of your asparagus bed, figure that each mature plant will produce 15 to 20 spears a season, and that each plant requires 12 to 18 inches of row space. Since asparagus roots are wide-ranging, allow four to six feet between rows of asparagus, as well as between asparagus and other crops.

Prepare the Soil

Start by completely removing the weeds - once the bed is established, it's difficult to get rid of weeds without harming the roots. Then dig a trench eight to ten inches deep and about 12 inches wide. Pile the excavated soil to one side; you'll use it later to cover the growing plants. Sprinkle in a complete fertilizer that is high in phosphorous and potassium (to promote vigorous root growth), such as a 5-10-10 formula, applying two pounds to each 25 feet of row. Also, add lime if the pH of your soil is below 6.8 - asparagus does not grow well in acid soils. Finally, dump in a couple of inches of compost or well-rotted manure and dig all the amendments into the bottom of the trench.

Plant the Crowns

Mold the soil in the trench into small mounds, spaced 12 to 18 inches apart. Set a crown on each mound with it top - the side with buds - facing upward and gently spread out the roots. Cover the crowns with two inches of your reserved soil, leaving the rest to fill the trench later on. Water well.

Gradually Fill the Trench

The first shoots should appear within a couple of weeks. As they grow, fill the trench a little at a time with your reserved soil. By the end of summer, the trench should be filled in at a level even with or slightly higher than the surrounding soil.

Care

During the first growing season, let all of the shoots leaf out to nourish the roots. Give the plants an inch of water each week if it doesn't rain, and pull any weeds at they appear. Once the trench is filled in, mulch the plants with salt hay or leaves.

In the fall, the ferny growth will brown. In regions with cold winters (USDA Zone 5 and colder), leave the dried stems in place to catch the snow, and plan to cut them in the early spring before growth resumes. In milder climates, it's better to remove the ferns to avoid carrying over foliar diseases. In all climates, topdress the bed in the spring with aged manure or compost.

Harvest

Gardeners used to wait two full years to make their first harvest. However, research has shown that a light harvest in the spring the year after planting does not harm if you limit it to a couple of weeks. The next year, you can extend the harvest to four to six weeks, and even longer -- up to eight weeks -- in the following years. To harvest, use a sharp knife to cut just below the soil, or use you fingers to snap off the spears when they are five to nine inches long.

If emerging spears are thinner than a pencil, stop harvesting. It's time to allow the foliage to grow again, to provide nourishment for future crops.

ASPARAGUS VARIETIES

Older asparagus varieties, such as 'Martha Washington' produce both male and female plants. The female plants are less desirable because they put their energy into making seeds, which reduces their spear production, and overpopulate the bed with volunteer plants. Recently, researchers at Rutgers University have introduced several highly productive, all-male hybrids that also have tolerance to asparagus rust and fusarium crown rot. Adapted to most climates, these include 'Jersey King', 'Jersey Giant' and 'Jersey Knight'. A good choice for warmer areas (Zone 5 and above) is predominantly male 'UC 157', which produces spears even when harvest weather is hot. 'Purple Passion' is deep purple in color, it grows well in all regions. --J.S.