Asparagus is a highly rewarding perennial vegetable, offering fresh spears each spring for many years once established. These plants are grown from structures called crowns, which are essentially one-year-old root systems. The depth at which these crowns are planted is the most important factor determining the success and longevity of the asparagus bed. A properly planted bed can remain productive for 15 to 20 years or more. Achieving the correct depth ensures the crown is protected and has sufficient soil support to produce thick, healthy spears.
Preparing the Permanent Planting Bed
Selecting the correct site is the first step. Asparagus requires full sun exposure and soil that drains very well, as waterlogged conditions lead to root rot.
To begin, excavate a trench approximately 12 inches wide and 8 to 10 inches deep. This creates a spacious environment for the extensive root system that will develop over time.
Once dug, loosen the soil at the bottom and amend it with organic matter such as compost or manure. This provides a nutrient-rich base and improves drainage. A small mound or ridge, about 3 to 4 inches high, is then formed down the center of the trench floor.
The Crown Placement and Initial Depth
Planting the crown correctly is a precise maneuver that sets the stage for the plant’s entire lifespan. The one-year-old crown is placed directly over the prepared mound in the trench, ensuring the roots are carefully fanned out and draped down both sides of the ridge. The roots should be spread evenly to encourage balanced growth and strong anchoring in the soil.
This placement allows the crown’s central growth bud to sit at the highest point of the mound, with the roots extending downward like the legs of a spider. After positioning, the crown is covered with a layer of finely sifted soil, gently filling the trench until the crown is buried by exactly 2 to 3 inches of earth. This small layer of soil is sufficient to protect the crown while allowing the plant to push through easily.
The top of the crown should initially sit roughly 6 inches below the surrounding ground level. This deep positioning protects the root mass from freezing and cultivation damage, ensuring the crop is long-lived. Planting too shallowly risks desiccation and winter cold, while planting too deep can exhaust the plant as it struggles to send up spears.
Backfilling the Trench and First-Year Care
The planting process is not completed by simply covering the crown; the remaining portion of the trench must be filled gradually. As the first spears begin to emerge and grow approximately 2 to 3 inches tall, an additional 2 inches of soil should be added back into the trench. This process is repeated several times throughout the first growing season.
The slow, staged filling continues until the trench is completely level with the surrounding garden surface. This method ensures that the young spears always have light exposure while simultaneously encouraging the development of new feeder roots higher up on the crown. By the end of the first year, the crown will be buried a full 8 to 10 inches beneath the soil surface, fully established at its permanent depth.
First-year care requires leaving the plants completely undisturbed, meaning no harvesting of spears. All spears must be allowed to grow into tall, fern-like foliage, which photosynthesizes and generates the energy reserves necessary for future production. The crown relies on this energy to fuel the next year’s harvest and ensure its long-term viability.
Consistent, deep watering is necessary, especially during dry periods, to promote vigorous root growth. The bed must also be kept free of weeds, as young asparagus plants cannot compete for nutrients and moisture during this establishment period. Following these steps ensures the crowns will be ready to provide a light harvest in the second spring and a full harvest by the third year.