By Katie Winslow, U of M Extension
For many people, asparagus (Asparagus officinalis) is a true sign of spring in their gardens. Asparagus is a long lasting, perennial plant from which you consume the shoot or spear. Later in the summer, these shoots develop into tall plants with fine leaves or ferns. The ferns store energy in the underground portion of the plant to produce next year’s spears. During this time of year many people have questions about their asparagus and how best manage that area of the garden.
Prior to planting asparagus, it is important to have your soil tested. Asparagus likes a soil with a pH of 6.5 to 7.0 and will not tolerate acidic soil. Fertilizer applications can be determined after soil analysis. In an established asparagus patch, fertilizer does not need to be applied until after harvest is done due to the root system being able to store large amounts of nutrients. Never use a fertilizer that also contains a weed killer (weed and feed) on asparagus as it may kill your vegetables.
Asparagus is a perennial plant that can live for 15 years or more. Choose a fertile, sunny, well-drained site with soil that holds moisture. Late spring frosts can kill emerged spears. Avoid low-lying areas. Asparagus plants have a deep root system. Avoid shallow soils or soils prone to water saturation. If the asparagus bed is to be part of a larger vegetable garden, the best place is at the north end of the garden, so the tall ferns do not shade the other crops.
Asparagus plants will not show signs of drought stress so use extra care to ensure proper watering during the growing season. Asparagus needs at least one inch of rain weekly. If it is not forecasted to rain, soak the soil at least once a week. For sandy soils, water will be required more than once per week.
If perennial weeds begin to infest the asparagus bed, dig them out in late fall after frost has killed all of the ferns. Do not dig too deeply, and try to leave the ferns in place. They will catch and hold snow on the bed, warming the crowns. Dig annual weeds as they emerge. Do not till or hoe soil more than three to four inches deep to avoid damaging feeder roots.
More information on asparagus can be found at –http://www.-extension.umn.edu. Contributors to this article include Cindy Tong and Jill MacKenzie, University of Minnesota Extension. If you have further questions about asparagus or other vegetables you can contact Katie Winslow, Extension Educator for Horticulture, Small Farms and Local Foods in Stearns, Benton and Morrison Counties at (320) 255-6169 ext. 1.