Asparagus is a perennial vegetable that, once established, can produce tender spears for 15 to 30 years, making the initial planting steps important for its long-term success. The plant grows from underground buds called crowns, and planting these crowns at the correct depth is a significant factor in ensuring a robust and productive asparagus patch for decades to come. This process requires creating a deep trench and then gradually filling it in over time, which encourages the development of a deep, strong root system.
Preparing the Planting Site
Selecting the right location is the first step toward a successful asparagus bed, as the plants will remain in this spot for many years. Asparagus needs a site that receives full sun, meaning a minimum of six to eight hours of direct sunlight each day. The location must also have excellent drainage; waterlogged soil can quickly lead to crown rot.
The soil should be loosened deeply, ideally to a depth of 12 to 18 inches, to accommodate the extensive root structure. Prior to planting, incorporate a generous amount of organic matter, such as compost or aged manure, to improve both fertility and drainage. To begin the planting process, a trench should be dug, generally measuring about 12 inches wide. The depth should be between six and twelve inches, depending on the soil type. For heavy clay soils, a shallower trench around six to eight inches is better, while sandy soils can accommodate the deeper end of the range.
The Crucial Planting Depth and Technique
The goal of the planting technique is to achieve a final depth where the crown sits six to eight inches below the soil surface, but this depth is not reached all at once. Inside the prepared trench, small mounds of soil should be created, spaced 12 to 18 inches apart, running down the center of the trench. These mounds should be a few inches high and provide a stable base for the crowns.
Each asparagus crown is placed on top of one of these mounds, ensuring the buds are pointing upward. The fleshy, spider-like roots are then carefully draped and spread out evenly down the sides of the mound, allowing them to fan out into the prepared soil. This positioning is important because it prevents the roots from growing straight up, which can happen if they are simply bunched together.
After placing the crown, it is initially covered with only two to three inches of soil, which is enough to secure the roots and allow the first shoots to emerge. This initial, shallow covering leaves the rest of the trench empty. As the first spears, or ferns, grow three to four inches tall, more soil is gradually added to the trench, covering the new growth and leaving only the top portion of the fern exposed. This process is repeated several times throughout the first growing season until the trench is entirely filled to ground level. The technique of gradually backfilling the trench encourages the crown to produce new buds higher up on the root system, which results in a more robust and deeply anchored plant.
First-Year Care and Longterm Establishment
Immediately after the initial planting and covering, the crowns require a thorough watering to help settle the soil around the roots. Throughout the first year, consistent moisture is necessary for the crowns to establish. They should receive about one to two inches of water per week, either from rainfall or supplemental irrigation. Young crowns need this consistent moisture for strong root and fern growth, even though the plants are drought-tolerant once mature.
Weed control is important during the first two years, as weeds compete heavily with the young asparagus for water and nutrients. Weeds should be removed by hand or with shallow cultivation to avoid disturbing the newly forming crown and its roots. The most significant rule for long-term production is to avoid harvesting any spears during the first two full growing seasons.
Allowing all spears to grow into tall, feathery ferns for the first 24 months is essential. The ferns are responsible for photosynthesis, which stores the energy in the root system. If spears are harvested too soon, the plant cannot store enough energy, resulting in a weakened crown and reduced future harvests. Harvesting can typically begin lightly in the third year, once the root system has developed sufficient reserves to support sustained production.