Asparagus is a highly valued perennial vegetable, celebrated for its tender spears that emerge early in the spring. This long-lived plant can produce a harvest for 15 to 20 years or more, making site selection and proper planting a long-term investment. Asparagus requires a location that receives full sun (ideally eight or more hours daily) and thrives in loose, deep, well-drained soil. Selecting an appropriate site and preparing the bed correctly are the first steps toward establishing a productive asparagus patch.
Optimal Planting Time in Pennsylvania
The best time to plant asparagus crowns in Pennsylvania is in the early spring, as soon as the soil is workable. This timing allows the crowns to establish a strong root system before the onset of summer heat. Gardeners should aim to plant two to four weeks before the last average frost date for their specific region, which generally falls between March and early May.
Planting in early spring ensures the crowns are dormant, which minimizes transplant shock and promotes rapid root growth once the soil warms. Ideally, the soil temperature should be around 50°F for the most vigorous growth. Starting with one-year-old crowns is the standard method, as it significantly reduces the waiting time compared to planting from seed. This early window provides maximum time for the plant to store energy in its roots during its first crucial growing season.
Site Preparation and Crown Placement
Thorough site preparation is necessary for a perennial crop like asparagus, which will remain in the same location for decades. The soil should be loose and deep, with a neutral pH of around 7, so it is recommended to perform a soil test before planting. Before planting, remove all perennial weeds and their roots, which can compete heavily with young asparagus plants for resources.
To plant the crowns, dig a trench about 6 inches deep and 12 inches wide. A generous amount of well-composted manure or compost should be incorporated into the soil at the bottom of the trench. The crowns should be soaked in water for about twenty minutes before planting to rehydrate them.
Lay the crowns with the buds facing upward, spreading the fleshy roots out along the bottom of the trench, and spacing them 18 to 24 inches apart. Initially, cover the crowns with only two to three inches of soil. As the first spears emerge, gradually add another inch or two of soil, repeating this process throughout the season. Continue backfilling the trench until the soil is level with the surrounding garden bed, ensuring the crowns are buried deep enough to support future harvests.
Essential Care During the Establishment Year
The first year of growth is dedicated entirely to developing a robust root system, which requires consistent maintenance. The most significant threat to newly planted asparagus is weed competition, so the bed must be kept completely weed-free. Hand-pulling weeds gently is the best method to avoid disturbing the delicate, shallow roots of the young crowns.
Consistent soil moisture is necessary, requiring watering once or twice a week during dry periods, ensuring the bed does not become saturated. Allowing the spears to grow into tall, fern-like foliage is the most important action in the establishment year. This fern growth is responsible for photosynthesizing and sending energy back down to the crown for storage.
In late fall, after the foliage has turned completely brown following a hard frost, cut the ferns down to about one inch above the ground. Remove the dead foliage from the bed to prevent it from harboring disease or pests over the winter. Applying a layer of mulch, such as straw or aged compost, helps suppress weeds and regulate soil temperature for the dormant crowns.
Understanding the First Harvest
Patience is a requirement when growing asparagus, as a full harvest takes three years to establish. In the planting year, no spears should be harvested; all growth must be allowed to turn into ferns to strengthen the crown. Harvesting too early will deplete the plant’s stored energy and could severely stunt its long-term productivity.
A limited harvest can occur in the second year, if the plants appear strong and healthy, lasting about two weeks. The first full harvest begins in the third year, when the patch is mature enough to sustain a longer harvest window, typically lasting six to eight weeks. Harvestable spears are at least the thickness of a pencil and six to eight inches tall. The proper technique is to snap the spear off at or slightly below the soil line, or to cut it with a sharp knife, which encourages more spears to emerge.