Extension Educator, Horticulture
What vegetable grows wild along railroad tracks in Illinois? Except for the occasional "wild" tomato plant that appears in my compost pile, asparagus is one of the few traditional vegetables found in the wild. Asparagus is a hardy, durable perennial and a well prepared garden patch will last 20 to 30 years. I have a patch that is about 60 years old and is still producing. Asparagus is one of the earliest vegetables to harvest in the spring and has many characteristics which make it worth growing. For instance, asparagus spears are less expensive and generally of better quality when home grown. It is also easy to grow and attractive. The ferny foliage is lovely as it turns from green to a golden yellow in fall. Plant mums in front of your asparagus patch and you have a beautiful late season flower bed.
Asparagus should be planted as soon as the soil can be properly prepared in the spring. Usually asparagus is started from one-year-old crowns or plants. The crowns resemble octopus with their crown of buds and pencil sized roots radiating from the crown. Asparagus can be started from seed, but it will delay production a year.
Asparagus plants are naturally male or female plants. They can be purchased as female plants, male plants or predominately male plants. Male plants can be 3-5 times more productive than females. Males also do not produce seeds, which can become weedy.
Asparagus varieties to consider for Illinois include Mary Washington, Martha Washington, Waltham Washington and Jersey Centennial. However for higher yields, consider the male hybrids of Jersey Giant, Jersey Knight and Jersey Prince.
To plant asparagus, place crowns in a trench 12 to 18 inches wide and 6 inches deep. Crowns should be spaced 9 to 12 inches apart in the trench. Spread the roots outward with the buds of the crown facing up. Cover the crown with 2 inches of soil. As the stems lengthen through the season, fill the remaining portion of the trench with soil. This planting process gets the crown deeper into the soil without forcing the plant to push through 6 inches of soil all at once.
Asparagus should be fertilized in the spring for new plantings (first 3 years) and right after the last harvest in June or July for older plantings. Apply 10-10-10 or similar fertilizer at the rate of 2 to 2.5 pounds per 100 square feet or use compost or well rotted manure. Asparagus can be harvested the third year after planting crowns, but harvest for only a month the first time. After the third year the spears can be harvested through May or June. To harvest, grasp 5 to 8 inch long spears at the base and bend them toward the ground. The spear will snap where it is free of fiber. Spears may also be cut with a knife, but make sure not to damage any of the emerging spears. Quality deteriorates rapidly after harvesting so any asparagus that is not eaten immediately should be processed or refrigerated.
Weeds and especially grasses can be a problem in asparagus bed. In early spring do a shallow hoe cultivation so as not to damage the emerging spears but to remove weed seedlings. Apply compost mulch after harvest. An old gardener's tale is to apply rock salt to the asparagus patch to keep grass seedlings from germinating. It may work, but it is not a healthy practice for the growth of the asparagus. A sure case of dying from the cure.
Be sure to stop by the Master Gardener display at the Home and Garden Show at the Assembly Hall March 13th and 14th.