Asparagus is a perennial vegetable that can produce tender spears each spring for 15 years or more once established. Starting a new asparagus patch requires careful planning and the right planting material. The most common and efficient way to begin an asparagus bed is by planting an asparagus crown, rather than using seed. This article defines the crown’s biological structure and explains how this unique plant part establishes a long-lived, productive asparagus harvest.
The Anatomy and Function of an Asparagus Crown
The asparagus crown is the subterranean, dormant root structure from which edible spears emerge each spring. Biologically, the crown is a modified stem, or rhizome, that grows horizontally just below the soil surface. This rootstock serves as the plant’s permanent base, allowing it to return year after year.
Attached to the rhizome are two main structures that govern the plant’s life cycle. Fleshy storage roots radiate out to store carbohydrates, which are the energy reserves produced by the foliage. The rhizome also features numerous buds, or “eyes,” which are the growing points that initiate the new season’s growth.
These buds swell and push upward through the soil as the tender shoots harvested as asparagus spears. Unharvested spears grow into a tall, feathery structure known as a fern, which acts as the plant’s “food factory” through photosynthesis. The crown’s stored energy ensures the plant survives winter dormancy and produces a vigorous crop the following spring.
Crowns Versus Seeds: Understanding Propagation
While asparagus can be started from seed, crowns are the standard material for establishing a new bed because they accelerate the time to harvest. Crowns are typically one-year-old plants that have already developed a substantial root system and energy reserves. This pre-growth bypasses the slow, delicate seedling stage required when starting from seed.
Planting crowns saves a full year compared to starting from seed, allowing a light harvest to begin in the second year after planting, instead of the third year. Crowns offer a more established and resilient start, as they are less susceptible to environmental stresses and competition from weeds than fragile seedlings.
Establishing and Caring for New Crowns
Asparagus crowns should be planted in the early spring as soon as the soil can be worked, ensuring they have the entire growing season to establish. The process begins by digging a trench 8 to 12 inches wide and 6 to 10 inches deep. Well-drained soil rich in organic matter, with a pH between 6.5 and 7.0, is preferred for optimal growth.
The crowns are placed into the trench with their roots spread out and the growing buds pointing upward. They should be spaced 12 to 18 inches apart to allow room for the extensive root system to develop. The crowns are initially covered with only two or three inches of soil. As the spears grow and turn into ferns, the trench is gradually filled in over the season.
The most important rule during the first year is to resist harvesting any spears, allowing all growth to mature into ferns. The ferns must be allowed to grow and photosynthesize all summer long, creating and storing the energy the crown needs to produce a strong harvest in future years. Cutting the ferns back too early depletes the crown’s reserves and weakens the perennial plant.