Asparagus is a hardy perennial that requires considerable work to establish a good asparagus bed but is well worth the effort since a well-planned bed can last from 15 to 25 years. Make sure you plant your asparagus at the side or end of the garden where it will not be disturbed by normal garden cultivation.
Although the list of common varieties has changed in recent years standard varieties like Mary Washington, Martha Washington and Waltham Washington can still be easily obtained. A number of new varieties that are predominantly all male have been introduced in to common usage. The female plant bears seed, which take considerable energy from the plant and they sprout new seedlings which causes overcrowding in the bed. The male plant produces thicker, larger spears since they do not expend the energy into producing seeds.
A line that produces only male plants was discovered and has been incorporated into some truly amazing varieties. Jersey Giant, Jersey Knight, Jersey Prince, Syn 53, Syn 4-362, UC 157 and Viking KBC are new hybrids with larger yields.
When To Plant
Asparagus should be planted as soon as the ground can be worked in the spring. The easiest and quickest way to start asparagus is to start with one-year-old crowns or plants. If you prefer you can start plants from seed but this will add a year to the process of establishing the bed.
Spacing & Depth
Start preparing soil about a year before planting by mixing in large quantities of organic matter, such as composted manure, compost, and green manure crops. Mix 2 to 3 pounds of 13-13-13 fertilizer per 100 square feet into the soil and lime to a pH of 6.0 to 6.5. Asparagus does poorly at a soil pH below 6.0.
Place the plants in a trench 12 to 18 inches wide and a full six inches deep. The crowns should be spaced 9 to 12 inches apart. Spread the roots out uniformly, with the crown bud side up, in an upright, centered position, slightly higher than the roots.
Cover the crown with two inches of soil. Gradually fill the remaining portion of the trench during the first summer as the plants grow taller. Asparagus has a tendency to "rise" as the plants mature, the crowns gradually growing closer to the soil surface. Many gardeners apply an additional 1 to 2 inches of soil from between the rows in later years.
As asparagus plants grow, they produce a mat of roots that spreads horizontally rather than vertically. In the first year, the top growth is spindly. As the plants become older, the stems become larger in diameter.
The female plants develop more spears or stems than the male plants, but the stems are smaller in diameter. With normal open-pollinated varieties, gardeners plant both male and female plants in an approximate ration of 1:1. After the first year, small red berries form on the female plants in late summer. These then fall to the ground, sprouting plants that essentially become perennial weeds in the asparagus bed.
Following freezing weather in the fall, the asparagus tops should be removed to decrease the chances of rust disease overwintering on the foliage.
Because asparagus remain in place for years, advance soil preparation helps future production greatly. Working green manure crops, compost, manure, or other organic materials into the proposed bed well in advance of planting is a good approach. Asparagus should be fertilized in the same way as the rest of the garden the first 3 years. In the spring, apply 10-10-10, 12-12-12 or 15-15-15 fertilizer at the rate of 20 to 25 pounds per 1,000 square feet of area or 2 pounds per 100 square feet and incorporate with soil tillage. Starting in the fourth year, apply the same amount of fertilizer but delay application until June or July (immediately after the final harvest). This approach encourages vigorous growth of the "fern," which produces and stores nutrients in the roots for next year’s production season.
Weeds and grasses are the worse problems with asparagus. They compete with the developing spears, make an unsightly area in the garden and significantly decrease yield and quality. Start frequent, light, shallow cultivation early in the spring in both young plantings and mature patches that are being harvested.
Asparagus can be harvested the third year after planting crowns, but for no more than one month the first season. The plant is still expanding its root storage system and excessive removal of spears weakens the plants. During the fourth year and thereafter, the spears may be harvested from their first appearance in the spring through May or June (as long as 8 to 10 weeks).
Harvest spears 5 to 8 inches in length by cutting or snapping. To cut a spear, run a knife into the soil at the base of the spear and carefully sever it. Because the spear is cut below the point where fiber develops, it becomes necessary to remove the fibrous base from the tender stalk. Cutting may damage some spear tips that have not yet emerged from the ground. To snap a spear, grasp it near the base and bend it toward the ground. The spear breaks at the lowest point where it is free of fiber.
Either method is acceptable. Cutting is often preferred by commercial growers and snapping by home gardeners. Asparagus deteriorates rapidly after harvest. If it is not eaten immediately, it should be processed or refrigerated.
Asparagus beetles are commonly found in home plantings. If numerous, they may be controlled by a suggested insecticide or by handpicking.
Asparagus rust can be a problem in the Midwest. Moisture left on the plant for 10 hours can help to spread the disease. Plant resistant varieties.