By Richard Jauron, Greg Wallace
It's the time of year when wild asparagus hunters are taking to roadside ditches and railway right-of-ways in search of this spring delicacy -– a hunt that is rivaled only by the woodland hikes to find morel mushrooms. Coming home with a bounty of fresh greens is a treasure to be savored every spring. For the less adventurous and gardeners that want a "patch" all their own, this is also a good time to plan, purchase and plant asparagus in the home garden. Horticulturists with Iowa State University Extension and Outreach recommend asparagus varieties for Iowa gardens and share how to properly plant and harvest a home patch of asparagus. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.
What would be a good planting site for asparagus?
Carefully consider possible planting sites, as asparagus is a perennial crop. A well-maintained asparagus planting may be productive for 15 to 20 years.
Asparagus performs best in well-drained soils in full sun. Planting sites should receive at least six hours of direct sun each day. Avoid shady sites near large trees and buildings. Raised beds are a good planting option for gardeners with poorly drained soils.
What are some good asparagus varieties for the home garden?
Asparagus is dioecious. Dioecious plants produce separate male and female plants. Male asparagus plants live longer and are more productive than female plants. Excellent all-male asparagus varieties (cultivars) for the home garden include ‘Jersey Giant,’ ‘Jersey Knight,’ ‘Jersey King,’ and ‘Jersey Supreme.’ ‘Mary Washington’ and ‘Martha Washington’ are good standard asparagus cultivars. (A planting of ‘Mary Washington’ or ‘Martha Washington’ will include both male and female plants.) ‘Purple Passion’ is a distinctive cultivar with purple shears.
When is the best time to plant asparagus?
The best way to establish an asparagus planting is to plant one-year-old crowns. Asparagus crowns can be purchased at garden centers and mail-order nurseries. Early spring (April to early May) is the best time to plant asparagus in Iowa.
How do you plant asparagus?
Asparagus crowns should be planted in shallow trenches or furrows. The planting depth depends on the soil type. Asparagus crowns should be planted eight to 10 inches deep in light, sandy soils, but only six inches deep in heavier soils. Space crowns 12 to 18 inches apart in rows that are four to five feet apart. Place asparagus crowns in the bottom of the furrow (buds pointing upward). Spread out the roots of the asparagus plants. After planting, completely fill the trench with soil. (For many years, it has been a common practice to cover the asparagus crowns with two inches of soil and gradually fill the trench as the asparagus grows. However, research has found the gradual filling of the furrow is unnecessary.)
After planting asparagus, when can I begin to harvest spears?
Asparagus plants should be allowed to become well established before any spears are harvested. No spears should be harvested during the first growing season. Asparagus can be harvested over a three to four week period during its second growing season. In following years, asparagus plantings can be harvested until early to mid-June. Harvest asparagus by cutting or snapping the spears when they reach a height of six to eight inches.