How To Grow And Harvest Asparagus
Have you ever tried to grow asparagus? We can tell you how to grow and harvest it. It is a delicious vegetable and is easy to grow and take care of once established.
Asparagus is a highly productive vegetable best suited to cooler areas. Grown for the stems or spears, a well-tended planting yields 8 to 10 pounds or more per 100 square feet of bed or 24 to 30 pounds per 100 feet of row. For most home gardeners, one row is adequate.
An asparagus planting lasts 15 to 25 years without replanting if it is well cared for and the climate is suitable. It does not do well if summers are extremely hot and long and winters are mild.
Asparagus is grown from 1-year-old plants or "crowns" planted in January or February. Crowns grow from seeds planted in flats or peat cups in October for January transplanting, or they are transplanted from an existing asparagus bed. To get healthy, vigorous plants, buy 1-year-old crowns from a nursery or garden center or order them from a seed catalog. It takes 1 year to grow a good crown.
It requires 3 years from the time the crown is planted until the bed is in full production. Do not harvest the spears until your plants are three years old. Buds emerge from the soil when the soil warms in early spring and develop into edible spears. If these spears are not harvested and are allowed to continue growing, they develop into "fern-like" stalks.
From these "ferns", the mature plant manufactures food and stores it in "storage roots." This reserve supplies the energy necessary to produce spears the following year.
Asparagus does best in deep, well-drained soil with full sunlight.
Soil Preparation
Since an asparagus planting lasts many years, good seedbed preparation is essential. The soil should be free of trash, soil insects and weeds before planting.
In late fall, spread a 3-inch layer of organic matter such as manure, rotted sawdust or compost over the beds. Till or spade to a depth of 10 to 12 inches and turn the soil so all organic matter is covered. Asparagus grows well in high pH soils but does not do well if the soil pH is below 6.0. Test the soil before planting the beds and add lime if needed to adjust the pH to 6.5 to 7.0.
Fertilizing
Before planting new asparagus beds, mix in 2 to 3 pounds of 10-20-10 or a similar analysis fertilizer per 20 feet of row. If you have had your soil tested, follow the instructions from your soil test. When fertilizing you should always follow the instructions on your fertilizer bag.
For established beds scatter 1 to 2 pounds of 10-20-10 fertilizer per 20 feet of row before growth begins in the spring. After your harvest your asparagus, add an additional 1 to 2 pounds per 20 feet of row. Use a nitrogen fertilizer such as 21-0-0 for this feeding. Water the fertilizer into the soil. If you find your spears are fibrous, you need to fertilize your crop of asparagus.
Varieties
Martha Washington, UC 157, Jersey Giant and Mary Washington are the most common types of asparagus varieties and they produce well
Planting
Since asparagus will be in the same place several years, it is important to select the right spot. Asparagus plants make a good border around the edge of a garden or along a fence.
After asparagus beds are tilled, mark rows 4 to 6 feet apart. Dig a furrow 4 inches wide and 6 to 12 inches deep. Place the crowns in the furrow, cover with 2 to 3 inches of soil and firm the soil around the roots. Do not fill the entire furrow at once. Plant crowns 6 to 12 inches deep in loose soils and 4 to 6 inches in heavier soils.
Place crowns 12 to 14 inches apart. Planting too closely can cause small spears. Wider planting results in larger spears but lower total yield. Control weeds but do not injure the crowns. Fill the furrows gradually as the shoots grow. This covers small weeds, and they die from lack of light. By the end of the first season, the furrow reaches its normal level (figure 1). Deep planting of the crowns allows cultivation with garden tools or tiller (do not till too deep) without damage to crowns.
Watering
Asparagus plants like frequent, deep watering. Water the beds thoroughly as they become established Allow the top 1 inch of soil to dry before watering again. The time varies from 3 to 5 days depending on temperature. Asparagus roots reach 10 feet deep if the soil is adequate and moisture is available. Once established, watering should not be an issue.
Care During the Season
Keep weeds pulled or hoed from the beds. Asparagus beds require little care after the first 2 years. Control weeds without damaging the spears. In early spring, mix in the fertilizer before the spears begin growth (figure 2). Control weeds during the season by raking lightly or mulching. After the last harvest, cut back all top growth. Apply fertilizer and till lightly 1 to 2 inches to kill weeds.
Cover the bed with a 3-inch layer of clean straw, compost or other mulch material, water thoroughly and allow the plants grow the rest of the year. This helps insure a good harvest the next year (figure 3).
After the first hard frost/freeze of fall, cut fern tops off at ground level and mulch with manure. In southern areas the fern may not be killed by a freeze and should be removed in late November. Any spears which sprout may be removed and eaten.
Harvesting
Harvest asparagus spears from established beds for about 8 weeks. Do not harvest too soon from new planting. Wait three years.
Harvest spears when they are 4 to 10 inches long. To prevent spears from becoming fibrous, harvest at least every other day. The fibrous condition is caused by the spears being too old, or inadequate amounts of fertilizer. Spears with loosely formed heads are overmature.
Cut asparagus spears 1 to 2 inches below the soil level. At least one-half the length of the spear should be above the ground. Never cut the spear within 2 inches of the crown to avoid damage to the developed buds. Never cut asparagus spears above the ground and allow stubs to remain (figure 4). Discontinue harvest when spear diameter becomes less than 3/8 of an inch.
Some gardeners prefer white or blanched asparagus. This is grown by shading the spears with mounds of soil or mulch to exclude light.
