Asparagus is a long-lived perennial vegetable that can produce for two decades or more, making the initial planting choices exceptionally important. Establishing a successful asparagus patch depends on precise timing and thorough bed preparation, particularly in a state with variable climates like Colorado. Understanding Colorado’s unique growing calendar and preparing a deep, nutrient-rich home for the crowns is key to long-term success.
Understanding Colorado’s Growing Seasons
The diverse geography of Colorado means there is no single planting date for asparagus. Ideal timing is dictated by local soil conditions, specifically when the ground is workable and the soil temperature is adequate for root growth. Asparagus crowns should be planted in early spring as soon as the soil can be tilled, typically four to six weeks before the last expected hard frost date.
For the Front Range and Eastern Plains, this window generally opens in late March or early April. Higher-elevation mountain zones may need to wait until May or early June before the soil is ready. The soil temperature should be at least 50°F for the crowns to emerge and begin growing actively. Fall planting is generally discouraged in Colorado, as crowns benefit from a full spring and summer of growth before facing winter.
Preparing the Asparagus Bed
Because an asparagus patch is permanent, thorough bed preparation is essential for long-term production. The planting site must receive full sun (a minimum of eight hours of direct sunlight) and the soil must be well-drained. All perennial weeds, especially deep-rooted ones, must be completely removed before planting, as asparagus roots are sensitive to competition.
A soil test is recommended to determine existing nutrient levels and pH; asparagus prefers a slightly acidic to neutral soil (pH 6.5 to 7.5). Before digging the trench, thoroughly work a generous amount of organic matter, such as four inches of aged compost or well-rotted manure, into the soil to a depth of at least twelve inches. This deep amendment improves drainage and provides the foundation of nutrients.
Planting Methods and Techniques
Asparagus is most often planted using one-year-old dormant roots called crowns, which provides a head start over planting from seed. Dig a flat-bottomed trench about 12 to 15 inches wide and six to eight inches deep. A phosphorus-rich fertilizer can be mixed into the soil at the bottom of the trench to encourage deep root development.
The crowns should be spaced 12 to 18 inches apart, spreading the roots out radially and ensuring the bud clusters face upward. Cover the crowns with only one to three inches of soil as the initial backfill. As new spears emerge and grow taller, soil should be gradually added to the trench in two-inch increments. This incremental backfilling continues until the trench is level with the surrounding garden bed, which may take most of the first growing season.
Essential First-Year Maintenance
The first year focuses entirely on establishing a robust root system, requiring consistent care and a strict no-harvesting policy. Newly planted crowns need consistent moisture, which is challenging in Colorado’s arid climate. The bed should receive one to two inches of water per week, through rainfall or deep supplemental watering, to prevent the soil from drying out.
Weed control is the greatest threat to young asparagus, as competition can stunt root growth. Hand-pulling weeds is preferable to hoeing or tilling, which can damage shallow roots and new spears. By late summer, the spears develop into tall, fern-like foliage that collects solar energy to fuel the root system for the following year. After the first killing frost, which turns the foliage yellow and brown, the ferns should be cut back to the ground. This cleanup prepares the patch for winter dormancy and reduces the risk of pests or diseases.