Late spring is the season for local asparagus, and you can grow this perennial vegetable in your own garden. It takes some patience and effort to get an asparagus patch going, but once you do, the plants can live for 15 to 20 years.
University of Minnesota Extension says the edible parts of the asparagus plant are the spears, or stems of the plant. They grow from underground buds at the base of the root system and the buds and roots together are called “crowns.” Spears are harvested for no more than six to eight weeks from late May into early June. After that, spears are left to develop and grow leaves which are called ferns. The fern is an important part of the plant because it helps to store energy for next year’s spear production. Ferns should be cared for after harvest to keep the plant healthy and strong. The ferns can be attractive and you might consider this vegetable for edible landscaping.
University of Minnesota Extension says that asparagus needs well-drained soil and pH levels between 6.5 and 7.0. The plant will not do well in soggy areas or acidic soils. Asparagus also needs at least eight hours of sun daily and loose, deep soil is preferred.
Plan well ahead of starting an asparagus patch. At least a year in advance, have the soil tested and add the recommended fertilizer and amendments based on the soil test results.
You can start asparagus from seed, but it will take at least three years before you are able to harvest, and you should start seed in a special “nursery” area created in your garden. Most asparagus is started from purchased one-year-old crowns.
Asparagus is dioecious, meaning there are both female and male plants. Male plants are preferred because they tend to have more vigor and produce more shoots in the spring. Look for male plants with a resistance to asparagus diseases. Penn State University Extension recommends Jersey varieties developed by Rutgers University as well as Millennium.
When your garden area is ready, prepare a bed four feet wide and remove all weeds and their roots, Penn State says. Weeds can be a problem with asparagus. Be sure to stay on top of weeds, removing them by hand and mulching to help prevent their growth.
Plant crowns two to four weeks before the last average frost date. Dig a trench six inches deep and twelve inches wide. Penn State says you should soak the crowns in water for about 20 minutes before planting and lay them 18 to 24 inches apart in the trench. Cover with two to three inches of soil. After plants emerge, you can add more soil. Continue to add soil as plants grow and until the trench is filled in. Mulching helps to keep soil moist and suppress weeds.
The first two years, water the bed on a regular basis, but do not let it get saturated. Fertilize in the spring by top dressing with fertilizer or manure according to the soil test. Penn State says in the fall after foliage dies back, cut it back to about an inch above the soil and lay foliage over the bed for winter protection. Remove in the spring to prevent spread of disease. Add mulch again in the spring and keep an eye out for disease and insect damage. Keep the asparagus bed well-weeded.
Do not harvest any spears the first year to let the crowns become strong and established. The second year, you can harvest for a couple of weeks. By the third year, you can harvest for six to eight weeks. Snap off shoots six to eight inches in length just above the ground level.
