Asparagus is a long-lived perennial vegetable, capable of producing for 15 to 30 years once established. Because of this longevity, the initial planting must be handled with care to ensure a successful, multi-decade harvest. Aligning the planting time with the specific climate conditions of USDA Hardiness Zone 6 dictates the precise window for planting.
Decoding Zone 6 Planting Timing
The optimal time to plant asparagus crowns in Zone 6 is in the early spring, typically spanning from the last week of March through the end of April. This timing is determined by the condition of the soil, not the calendar date, and planting should occur as soon as the soil is workable. The soil temperature should ideally have warmed to around 50°F.
Planting the dormant crowns while the air is still cool, but after the danger of a hard, sustained freeze has passed, allows the roots to begin growing before the heat of summer arrives. This cool, moist period minimizes stress on the crowns and encourages rapid establishment.
One-year-old dormant crowns are the preferred planting material over seeds, as they reduce the time until the first harvest by at least a year. Starting with crowns ensures the plant’s energy is channeled directly into root development.
Preparing the Ideal Asparagus Bed
Since an asparagus bed can remain productive for two decades or more, preparing the site well in advance is a worthwhile investment. Asparagus requires a location that receives full sun, meaning at least eight hours of direct sunlight each day. The chosen site must also have excellent drainage, as the crowns are highly susceptible to rotting in soggy soil.
The deep root system of a mature asparagus plant can reach up to six feet deep, requiring the soil to be loosened to a depth of 12 to 15 inches before planting. It is important to remove all perennial weeds from the area, as they will aggressively compete with the young asparagus crowns for nutrients and water. Incorporating generous amounts of well-rotted compost or aged manure into the soil will improve both fertility and drainage. Asparagus thrives in a soil pH range of 6.5 to 7.0, so a soil test is recommended to determine if lime or other amendments are needed to adjust the acidity before planting.
Step-by-Step Planting Guide for Crowns
Planting begins by digging a trench that is approximately 10 to 12 inches wide and 8 inches deep in the prepared bed. A ridge or mound of soil, about 2 to 3 inches high, should be formed down the center of this trench. This mound provides a stable base for the crown and allows the roots to spread naturally downward and outward.
Place the dormant, one-year-old crowns on top of this ridge, ensuring the roots are draped evenly over the sides of the mound. Spacing the crowns 12 to 18 inches apart within the trench allows sufficient room for the mature plants to develop. If planting multiple rows, space the trenches 3 to 4 feet apart to accommodate the mature fern growth. Initially, cover the crowns with only 2 to 3 inches of the loose, amended soil, leaving the rest of the trench unfilled. As the first spears grow and emerge, gradually fill the trench with soil throughout the first growing season, being careful not to bury the emerging fern growth.
Crucial First-Year Establishment Care
The primary goal of the first year is to allow the crown to build a robust root system, so consistent care is necessary. New plantings require consistent soil moisture, which means providing 1 to 2 inches of water per square foot per week, especially during dry periods. Adequate water is essential for good root and fern growth.
Rigorous weed control is necessary, as young asparagus plants cannot compete with weeds. Hand-pulling weeds gently is the best method to avoid disturbing the fragile, newly establishing roots.
The most important rule for first-year care is the prohibition of harvesting any spears. All spears must be allowed to grow into tall, fern-like foliage, which collects energy through photosynthesis to feed the crown and store reserves for future production. In the late fall, once the ferns have naturally yellowed and died back, they should be cut down to the ground.