Asparagus is a highly valued perennial vegetable, celebrated for its tender spears that emerge early in the spring. Once properly established, an asparagus bed can remain productive for 15 to 30 years, offering a decades-long harvest with minimal effort. This longevity means the initial work of selecting the right site and planting correctly is necessary for long-term success. Starting a new bed requires patience and attention to detail, as the plant must first dedicate its energy to building a robust underground root system, or crown. This guide walks you through establishing a healthy asparagus patch that will reward you with years of delicious harvests.
Selecting and Preparing the Site
Because an asparagus bed is permanent, the planting location must be chosen with care. Full sun exposure, defined as a minimum of six to eight hours of direct sunlight daily, is required for strong growth and maximum spear production. Since the tall, fern-like growth of mature asparagus can shade other crops, position the bed along the northern edge of a vegetable garden.
Soil drainage is the most important physical characteristic, as crowns are prone to rot in soggy conditions. The soil must be loose and well-draining. Heavy clay soils should be amended with organic matter, such as compost or aged manure, to improve texture. Asparagus thrives in a near-neutral soil environment (pH 6.5 to 7.0), so a soil test is advisable before planting.
Completely remove all perennial weeds, which compete severely with young crowns. Deeply till the soil 12 to 15 inches deep to loosen it and ensure the deep-rooting crowns can spread without obstruction. Once the soil is prepared, dig a trench about 12 to 18 inches wide and 6 to 8 inches deep for the initial placement of the crowns.
Planting Asparagus Crowns
Asparagus is typically started from 1- or 2-year-old dormant, bare-root crowns, which are more robust and provide a quicker path to harvest than starting from seed. Plant these crowns in early spring as soon as the soil is workable to allow the longest possible season for establishment. Before planting, briefly soak the crowns in lukewarm water for 15 to 30 minutes to rehydrate the roots.
To position the crowns correctly, create a two-inch-high mound of soil in the center of the trench bottom. Place each crown on top of this mound, carefully spreading the long, fleshy roots out and down the sides. Space the crowns 12 to 18 inches apart within the trench to give each plant adequate room to develop.
Initial backfilling involves covering the crowns with only about two inches of loosened soil, gently firming it around the roots. This leaves the trench mostly open. As the first spears emerge and grow a few inches tall, gradually add more soil to the trench. Repeat this process until the trench is completely filled to ground level by the end of the season.
Essential Care During the First Growing Season
Consistent moisture is important during the first year of establishment while the young crowns develop their extensive root system. Keep the soil evenly moist, especially during dry periods, which may require watering up to one inch per square foot per week. Apply a layer of mulch, such as straw or shredded leaves, around the plants to help retain moisture and regulate soil temperature.
Rigorous weed control is essential, as competition will significantly stunt the growth of the newly planted crowns. Weeds must be removed by hand with care, since shallow hoeing or mechanical cultivation can easily damage the sensitive, spreading roots. Allowing weeds to grow unchecked compromises the plant’s ability to store energy for future harvests.
The most important rule during the first year is to resist harvesting any spears. All spears must be allowed to grow into tall, feathery ferns, which capture energy through photosynthesis. This activity fuels the development of a strong crown, storing the food reserves needed for future harvests. Once the foliage naturally dies back and turns yellow or brown in late fall or winter, cut the dried ferns down to a few inches above the soil surface.
Understanding the Initial Harvest Schedule
The harvest schedule is governed by the need to ensure the crown is fully established. The first spring after planting (Year One), no spears should be harvested, allowing all growth to transition into ferns to maximize root development. The second spring (Year Two) allows for a very light harvest, lasting only one to two weeks, and only if the plants appear vigorous.
The third spring after planting is typically the first year for a full, sustained harvest, which can last for four to six weeks. To ensure the long-term health of the bed, stop harvesting when the spears become noticeably thinner, often reaching the diameter of a pencil. This signals the crowns are depleting stored energy and need to grow ferns for the remainder of the season.
When harvesting, cut or snap the spears when they are six to ten inches tall, just before the tips open into the fern stage. Use a sharp knife to cut the spear at or slightly below the soil line, taking care not to nick emerging spears or the crown itself. Checking the bed daily is necessary during the peak season, as spears grow rapidly in warm weather.