Asparagus is a highly valued, long-lived perennial crop that can produce tender spears for 15 to 20 years or more once established. Growing this vegetable successfully requires specific planning and patience because the plant demands a permanent, well-prepared location. Success in Ohio requires adapting to the variable climate and often heavy soil conditions. The two to three years of establishment before the first full harvest will pay off with decades of fresh spring produce.
Selecting the Site and Preparing the Soil
The selection of a permanent planting site is the determining factor for a successful asparagus bed. Asparagus requires full sun exposure, meaning the area should receive at least eight hours of direct sunlight daily to produce energy for the crown. Because the plants grow into tall, fern-like structures, the bed should be placed on the north or west side of the garden to prevent shading other annual crops.
Drainage is a non-negotiable requirement, as the fleshy root crowns are highly susceptible to rot in waterlogged soil. Since Ohio often has heavy clay soils, selecting a natural hilltop or a slight slope is ideal to ensure water quickly moves away from the roots. If naturally excellent drainage is unavailable, incorporating significant amounts of organic matter, such as compost or aged manure, will help create the necessary loose, crumbly soil structure.
Before planting, test the soil to determine its nutrient profile and acidity level. Asparagus thrives in a soil pH range of 6.5 to 7.5, which is slightly acidic to neutral. If the test results indicate a pH below 6.5, agricultural lime should be incorporated deeply into the soil well before planting to raise the pH. Incorporating a pre-plant fertilizer, such as a 10-20-10 blend or bone meal, into the soil can support strong initial root growth.
Planting Asparagus Crowns
The best time to plant one-year-old asparagus crowns in Ohio is in the early spring, typically from March to mid-April, as soon as the soil is workable. Planting should occur before the crowns break dormancy and begin to sprout. Avoid planting into soil that is still cold and excessively wet, which can lead to crown rot. One-year-old crowns are preferred over seed, as they reduce the waiting time before harvest by at least a year.
The planting process begins by digging a trench 10 to 12 inches wide and 6 to 10 inches deep, depending on the soil type. For Ohio’s heavier clay soils, a shallower depth of about six inches is better, while sandier soils can accommodate a deeper trench. A two-inch high ridge or mound of soil should be created down the center of the trench floor.
The asparagus crowns are placed directly on top of this ridge, with the buds pointing upwards and the long, brittle roots spread out evenly. Crowns should be spaced 12 to 18 inches apart within the trench to ensure adequate room for the roots to expand. Immediately after placement, the crowns are covered lightly with about two inches of soil, and the area is watered thoroughly.
Establishing the Bed: Care During the First Two Years
The first two years after planting are a period of establishment focused on building a robust crown system that will support decades of harvesting. During the first growing season, the spears must be allowed to grow into tall, fern-like foliage without any harvesting. This foliage performs photosynthesis, creating and storing the energy reserves in the crown for future spear production.
Consistent moisture is important for the developing crowns, especially during the first summer when roots are not yet fully established. If rainfall is insufficient, supplemental irrigation should be provided to ensure the plants receive one to two inches of water per week. This watering is important during dry spells to prevent stress on the young plants.
Aggressive weed control is required during these non-harvest years, as young asparagus crowns cannot effectively compete with weeds for water and nutrients. Hand-weeding is the safest method, since cultivation tools can easily damage the shallow, developing roots. Gradually filling the planting trench with soil as the spears grow provides a natural way to smother small weeds and complete the planting process.
In the fall, after the foliage naturally turns yellow or brown, the ferns have completed transferring energy back to the crown. Although the dead ferns can be cut down in the late fall, leaving them standing over the winter provides insulation and helps catch snow, which delays early spring emergence. The dead stalks must be cut down to the ground before new growth begins in the early spring.
Harvesting and Maintaining a Productive Bed
Harvesting begins in the third year after the crowns were planted, allowing the plants two full years to mature. In this third year, the harvest period should be limited to only two to four weeks to allow the crowns to fully recover and continue building energy stores. From the fourth year onward, the bed can be harvested for a full period of six to eight weeks.
Spears should be harvested when they are seven to nine inches tall and have tight, unopened tips. The spears can be harvested by snapping them off with your fingers at or just above the soil line, or by cutting them with a knife about one inch below the soil surface. Snapping is the preferred method because the spear naturally breaks off where the tender part meets the tougher, woody base.
The harvest season should stop when the emerging spears become noticeably spindly, reaching the diameter of a pencil or thinner. Once harvesting stops, all remaining spears must be allowed to grow into full ferns for the rest of the season to replenish the crown’s food reserves. Asparagus beetles are a common pest, and the ferns should be monitored throughout the summer for signs of insect feeding, which can reduce the next year’s yield.
Annual maintenance involves applying a balanced fertilizer, often rich in nitrogen, immediately after the harvest season concludes. This application supports the vigorous fern growth needed to generate energy for the following spring. In the fall, after the dead ferns have been removed, applying a layer of compost or aged manure to the bed will help maintain soil fertility and structure.