Asparagus is a rewarding perennial that can produce fresh spears for decades with the right care. Growing this crop in Colorado, however, presents unique challenges due to the state’s distinct climate, characterized by high-altitude sun intensity, unpredictable spring weather, and aridity. Success relies heavily on understanding how to mitigate the dry air and intense solar radiation while preparing a permanent bed that will support the plant’s long-term root system. Establishing a healthy asparagus patch requires patience and a specific approach to site preparation and maintenance.
Site Preparation for Colorado Conditions
Selecting the correct location for your asparagus bed is the most important step for success in Colorado. Asparagus needs full, direct sun for at least eight hours a day to maximize spear production. A permanent bed must be chosen carefully, as these plants will remain in place for fifteen years or more once established.
The plant requires deep, well-drained soil to prevent crown rot, which occurs when roots sit in standing water. Colorado soil is often heavy clay, especially in urban areas, which holds too much moisture. Amending the bed with organic material, such as four inches of aged compost or well-rotted manure, is necessary to improve drainage and fertility. This organic matter should be thoroughly worked into the soil to a depth of twelve to fifteen inches before planting to allow the extensive root system to develop. Asparagus prefers a soil pH that is slightly acidic to neutral, around 6.5.
Planting Methods and First-Year Establishment
The optimal time to plant asparagus crowns in Colorado is in early spring, just after the last hard frost, when the soil is workable. While asparagus can be started from seed, planting one-year-old bare-root crowns is preferred because it saves a year before the first harvest. Choose healthy crowns with eight to ten large roots and soak them in lukewarm water for two to four hours before planting.
Begin the planting process by digging a trench approximately six to eight inches deep and twelve inches wide. Place the crowns in the trench, spreading the roots out in a starburst pattern, ensuring the buds face upward, and space them twelve to eighteen inches apart within the row. Initially, cover the crowns with only one to two inches of the amended soil. As the spears emerge and grow throughout the first season, gradually add two inches of soil until the trench is completely filled and level with the surrounding ground. This gradual backfilling encourages the crown to establish a deep, robust root system, which is the sole focus of the first year.
Ongoing Maintenance in Arid Climates
Managing water is a primary concern for established asparagus beds in Colorado’s arid climate. While the plants develop deep, fleshy roots that store water, they still require consistent moisture. Established plants need approximately one inch of water per week, while younger plants require up to two inches weekly for the first two years. It is most effective to water deeply and infrequently, soaking the soil thoroughly rather than applying light surface water, to encourage deep root growth.
Applying a thick layer of organic mulch, such as straw or shredded leaves, is beneficial to retain soil moisture and suppress competing weeds. Asparagus struggles against weeds, so maintaining a weed-free bed is important, especially since the shallow crowns can be damaged by aggressive cultivation.
Fertilization Schedule
Fertilization should occur twice a year: once in the early spring before the spears emerge, and again immediately after the harvest season concludes in mid-summer. This two-part feeding schedule helps fuel the spring spear growth and replenishes the energy reserves the crown needs for the rest of the growing season.
In late fall, after the feathery green ferns have completely died back and turned brown from the first hard freeze, they should be cut down to ground level. Removing this dead foliage helps prevent disease and prepares the crowns for the harsh, dry Colorado winter.
The Multi-Year Harvest Cycle
Patience is the gardener’s greatest tool when cultivating asparagus, as the perennial requires a significant waiting period before the first harvest. Crowns must be allowed to use their first two to three seasons exclusively to develop and store energy in their extensive root systems. Harvesting too early or too heavily will deplete these energy reserves, resulting in weaker plants and reduced production for many years.
The first light harvest can begin in the third spring after planting, or the second spring if the crowns are vigorous. During this initial harvesting period, only pick spears for a short window of two to three weeks. In the fourth year and beyond, a mature bed can be harvested for six to eight weeks, typically from late April into late June or early July in Colorado.
Spears should be harvested when they are six to ten inches tall and at least the diameter of a pencil. They can be snapped off by hand at ground level, or cut just below the soil surface using a sharp knife. Stop harvesting immediately when the emerging spears become consistently pencil-thin or smaller, which signals that the crown’s energy stores are becoming depleted. At this point, allow all remaining spears to grow into the tall, fern-like foliage that photosynthesizes and provides the essential energy for the next spring’s crop.