Ask the ISU Extension Garden Experts About: Growing Asparagus



When is the best time to plant asparagus? 

Early spring (April) is the best time to plant an asparagus bed in Iowa. Since asparagus is a perennial crop, carefully consider possible sites. Asparagus performs best in well-drained soils in full sun. In poorly drained sites, raised beds may be a solution. Avoid shady sites near large trees and buildings. 

What are some good asparagus varieties for home gardens in Iowa? 

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 for the home garden include ‘Jersey Giant,’ ‘Jersey Knight,’ ‘Jersey King,’ and ‘Jersey Supreme.’ ‘Mary Washington’ and ‘Martha Washington’ are good standard asparagus varieties. (A planting of ‘Mary Washington’ or ‘Martha Washington’ will include both male and female plants.) ‘Purple Passion’ is a distinctive variety with purple shears. 

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 6 to 8 inches deep in light, sandy soils, but only 4 to 6 inches deep in heavier soils. A small amount of well-rotted manure can be worked into the soil at the bottom of the trench before planting. Space the crowns 12 to 18 inches apart in rows that are 4 to 5 feet apart. Spread the roots out in the trench with the buds pointing upward. After planting, completely fill in the trench with soil. (Though commonly done in the past, it’s not necessary to gradually fill in the furrow as the plants grow.) 

After planting asparagus, how long must I wait before I can 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 6 to 8 inches. 

Is it possible to move an established asparagus bed? 

The roots of established asparagus plants are deep and quite extensive. As a result, transplanting attempts are usually unsuccessful. Large, old plants will be severely injured during the transplanting procedure. Some may die. Those that survive may never produce a good crop. The best way to establish an asparagus planting is to purchase one-year-old plants or crowns from a garden center or mail-order nursery. 
 
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