Revision Date: 02/01/2004 Ed Kee, Extension Specialist HG-10 Asparagus Asparagus is a perennial vegetable that can thrive for 15 years or more when well cared for. However, plants must grow two years in a garden before they can be harvested. Storage roots are attached to an underground stem called a rhizome. Storage roots and rhizomes make up the asparagus crown. When the soil is warm and soil moisture is favorable, buds sprout from rhizomes and develop into edible spears. Unharvested spears develop into attractive green, fernlike stalks (brush). Through photosynthesis, a mature asparagus plant produces carbohydrates and other essential nutrients that are translocated to the storage roots. These supply the energy required to produce spears during the following growing season. For this reason, it is important to protect the asparagus' fern-like foliage from insects, disease, and other injury. Spears should not be removed from plants during the first two growing seasons in their permanent location. In the Northeast, Rutgers Beacon, Jersey Giant, Jersey General and Jersey Supreme are recommended for home gardeners. These are available through major nursery and garden supplier. Temperature, Soil, and Fertility Asparagus grows best under maximum photosynthesis conditions: a long growing season and sunny days. Ideal day temperatures are 75 to 85 degrees Fahrenheit (23.9 to 29.4 C) with night temperatures from 60 to 70 F (15.6 to 21.1 C). Asparagus is most productive on deep, well-drained, sandy loam soils. The plants lose vigor, become more susceptible to root rot, and die in poorly drained areas or following prolonged high rainfall. Soil acidity (pH) should be maintained between 6.5 and 6.8. Medium fertility is best it produces a balance between top growth and root growth. Growing Asparagus http://ag.udel.edu/extension It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, color, sex, disability, age, or national origin. Plant healthy 1-year-old crowns. The Horticultural Standards of the American Association of Nurserymen are often used to identify the size of crowns. The terms "2 year" or "3 year" refer to the size the crowns have attained in one year's growth. A "2-year" crown is larger than a "1- year" crown. One-, 2-, or 3-year crowns may be used. Larger crowns have more vigor. It is difficult to get commercial crowns free of Fusarium root rot. One way to avoid Fusarium is to plant disease-free seed and grow your own crowns or seeding transplants. Crowns are produced by seeding in a nursery about two weeks before tomatoes are normally transplanted into the garden. Sow the seeds 1 inch deep and 3 inches apart in the row, with rows 2-1/2 feet apart. Sow 3 to 4 seeds for each crown you want to plant in the permanent bed. The following spring, when the ground has thawed but the plants are still dormant, carefully dig the crowns to minimize damage to the root system, and immediately plant them in the permanent bed. Plant asparagus with other perennial crops on the north or east side of the garden so the plants will not shade other vegetables or low-growing fruits. Asparagus can be planted along a fence if there is plenty of sun. In fact, the beautiful fern-like foliage grows 5 to 6 feet high and can be used as an ornamental summer screen. Female plants produce berries that become bright red in late summer and fall. The tops turn from green to an attractive yellow in fall and brown during winter. Before planting, broadcast and turn under 1.2 pounds of 5-10-10 fertilizer (or equivalent) per 100 square feet of area. If pH is below 6.0, include lime with the fertilizer. Plant crowns with the buds up in the bottom of a 6 inch deep V-shaped furrow, and cover with 1 to 2 inches of soil. Plant seedlings 1 inch deep on 3-inch-high mounds in the bottom of an 8-inch-deep furrow. Protect seedlings from water that may stand in the furrow and from soil that can wash into the furrow. Spacing for crowns and transplants is 12 inches apart within the row and 4 to 5 feet between rows. If only one asparagus row is planted, allow at least 3 feet between the asparagus and the closest vegetable crop. As the asparagus grows, gradually fill in the furrow with soil without covering any asparagus foliage. Furrows should be filled level by the end of the first growing season. Sidedress with 1.2 pounds of 5-10-10 fertilizer (or equivalent) per 20 feet of row in late July or early August. Spread the fertilizer on each side of the asparagus and cultivate it lightly into the soil. Adequate soil moisture is important during the first growing season. Weekly applications of irrigation sufficient to wet the soil 8 inches deep should be adequate. Thorough watering (2 to 3 inches of water) slowly applied every two weeks during dry weather is sufficient. After the first growing season, asparagus plants do not require frequent irrigation because of their deep and extensive root system.. In late winter or early spring of the second growing season remove the brush (old stalks) and overwintering weeds. Broadcast lime as needed to maintain the proper soil pH, plus 1.2 pounds of 5-10-10 fertilizer per 100 square feet of bed. In July, sidedress another 1.2 pounds of 5-10-10 fertilizer per 100 square feet. Remove brush during each succeeding winter or in the spring before the asparagus emerges, and broadcast lime if needed. At the same time, spread 3.5 pounds of 5-10-10 fertilizer (or . equivalent) per 100 square feet of bed. Rake the fertilizer and lime 1 to 2 inches into the soil, taking care not to damage the asparagus crowns. Maintain good foliage growth. Weeds shade asparagus, compete for water and nutrients, and reduce yields. Varieties Several hybrid varieties of asparagus are available. They usually give better yields and larger spears than standard varieties. They are, however, more expensive than standard varieties. Standard varieties can still be very productive in a home garden. Pests The most serious disease of asparagus is Fusarium root rot. Plant only disease-free seeds or crowns and select varieties that are tolerant to the disease (FT). Planting infested seed or infected crowns leads to a rapid buildup of the disease, causing drastically reduced yields. That area of the garden will also be permanently contaminated so that asparagus can never be grown there again. Fusarium infects the root system and kills feeder roots. As a result, plant vigor declines, spear size decreases, and weaker plants die. Fusarium can be identified by the reddish-brown color of affected feeder roots, reddish-brown spots and streaks on the storage roots, and large lesions on the base of spears and stalks at or below the soil line. Symptoms are much more severe when plants are under stress because of excessively long harvests, poor drainage, competition from weeds, and damage from insects and diseases. Rust is another common fungus disease in asparagus. It appears on the surface of stems and branches as small rust-colored spots containing spores that spread the disease. In the fall, the rust-colored areas produce black, overwintering spores that can infect the plant the following year. Severe rust destroys much of the foliage and reduces yields of the next year's crop. Fungicides can partially control rust. All the above listed varieties have some rust resistance. The asparagus beetle is a serious pest every year. There are two generations per year to deal with. The first does some feeding damage to the spears but they also lay small black eggs which stand out ward. Destroying the fern early in winter will reduce the number of beetles that survive the winter. If there only a few beetles, they can be handed picked and crushed. They beetles are somewhat hard to catch because they drop to ground and feign death. Washing the spears will remove the eggs. The adult beetles resembling slender ladybird beetles or they are bluish with white spots. The second generation lay rows of small, black, elongated eggs on asparagus brush. The larvae (small, gray to dark-green worms) cause most damage by eating the green fern, but beetles can also kill very young seedlings and seriously damage fern growth of mature plants. Insecticides, like carbaryl, cyclrpopencarboxylic acid, permethrin, pyrethrin, and methoxchlor be used control to them. When used in the harvest season, cut the spears, spray and then wait until required days to harvest interval is met. . Pesticide products included in this publication are generally listed as "active ingredient." The active ingredient is the material in the formulation that has the pesticidal activity. You will need to read the pesticide label on to determine if they contain the appropriate active ingredient. Regardless of the insecticide you choose, be sure the type of plant you want to spray and pest you want to control is listed on the label. Disclaimer: Mention or exclusion of any product is not intended to discriminate for or against any products. No endorsement is intended for the products mentioned, nor is criticism meant for products not mentioned. Please read labels before purchasing and then read them before using to ensure that target sites are p listed Harvesting Asparagus The crops must be grown in the permanent bed for two full growing seasons before harvest can begin. This is necessary for the plants to develop adequate storage root systems to produce spears during the first harvest season and beyond. Any harvesting or damage to the brush during the first two growing seasons dwarfs the plants and can reduce yields for the life of the bed. When the first spears emerge in the spring of the third growing season, merely snap off those with tight heads 7 to 10 inches long, leaving the tough stub on the plant. The upper portion that snaps off should be all green and all tender. Harvest all spears that come up during the season. The 2-4-6 week sequence is a good general rule for length of harvest season. Harvest for two weeks the third year the plants are in the garden, four weeks the fourth year, and six weeks the fifth year and subsequent years for the life of the bed. Two to three weeks after beginning harvest, 5 to 6 inches of soil may be carefully ridged over the rows. This lowers the temperature around the crown and increases spear size. Rake the ridge level right after the last harvest. If one day's harvest is not enough for a meal, or if the asparagus is to be consumed later, wash the spears, place the cut ends in a shallow pan of water and immediately refrigerate them. Good quality can be maintained for several days if the spears are kept at 35 to 40 F (1.67 to 4.44 C). One 40-foot row of asparagus will yield approximately 10 to 25 pounds of spears during an average season. Information for this fact sheet obtained from NE Region Extension publications. .
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