When I think of early season vegetables from the garden, one that comes to mind is asparagus, which I consider the “Cadillac of vegetables.” Asparagus is low in calories, high in Vitamin A and riboflavin and a good source of thiamin and fiber, which is important in one’s diet. Once established, your asparagus planting can be expected to produce for 25 years or more.
Asparagus is a perennial plant producing shoots, called spears, from buds formed on a rooted crown. Asparagus is dioecious, which means that it produces male and female flowers on separate plants. The female plants tend to produce larger spears than the male plant, but the male plants produce a larger number of spears per plant. The seedpod produced on the female plant turn bright red at maturity, which attracts birds, which feed on the seedpods and then distribute seeds over a wide area when the seed is dropped or passes through the digestive tract of the bird. In addition, the foliage that turns brown in the fall is attractive against the white snow during the winter.
Asparagus grows best in deep, well-drained, friable soils. Poorly drained soils may cause the plants to lose vigor and make them more susceptible to root (crown) rot. It is important to improve heavy soils prior to planting by adding aged manure or organic matter (such as compost), which will improve soil drainage.
Asparagus prefers a soil pH between 6.5 and 6.8. This is important because asparagus does not do well at pH levels below 6.0. Medium soil fertility is best to provide a balance between top growth and root growth, but the plant needs adequate phosphorous and relatively high amounts of potassium for maximum spear production.
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The asparagus planting should be located at the side of the garden since it is a perennial. Asparagus plantings can be established from healthy 1-year-old crowns or from transplants anytime throughout April. Crowns with buds facing up can be planted in the bottom of a 6-8 inch deep, W-shaped furrow and covered with 2 inches of soil.
Transplants can be planted on small mounds in the bottom of a similar furrow and then covered with 2 inches of soil. Both crowns and transplants should be planted 18 inches apart within the rows and with rows spaced about 4-5 feet apart or an equal distance from other vegetables in the garden. As the asparagus grows, carefully fill in the furrow with soil but avoid covering any foliage. Furrows should be filled in by the end of the first growing season. Suggested hybrid varieties for planting are: Jersey Giant, Jersey Knight, Jersey King and Viking kB3 (non-hybrid).
It is important that asparagus plants have two full growing seasons before their spears are harvested to allow them to develop an adequate storage root system. During the third growing season, snap off 7- to 10-inch-long spears with tight heads. The plants should produce 15 to 20 spears. Harvest all spears that come up during the harvest period, which should be 6 to 8 weeks.
Maintain the asparagus patch by keeping the beds weed free and fertilizing early in the spring each year with 2-3 pounds of a complete garden fertilizer (10-10-10) per 100 square feet. Work fertilizer into the soil.
After harvest, adding 1-2 pounds of ammonium nitrate or a fertilizer high in nitrogen per 100 square feet will ensure healthy summer growth. Take time to plant your own asparagus patch so you can enjoy the “Cadillac of vegetables” in the future.
Bill Lamont is a professor and extension vegetable specialist in the department of plant science at Penn State and can be reached by email at email@example.com.