Asparagus is grown from 1-year-old plants or "crowns," which are planted in early spring as soon as the soil can be worked. Asparagus plants take three growing seasons to reach full production, although light harvesting can begin in the second year. Once established, an asparagus planting will provide abundant harvests for fifteen to twenty-five years. Allow ten to twenty plants per person (15 to 30 feet of row).
Choosing a site to grow asparagus
Select a well-drained site in at least part sun; full sun is not necessary. Asparagus will thrive in slightly acid soil (pH of about 6.5), but will tolerate alkaline conditions up to 9.0.
Eliminate all weeds by repeated tilling. Loosen the soil to a depth of 12 to 15 inches, then mix in a 2- to 4-inch layer of compost. Prepare the bed by digging trenches 4 feet apart. The trenches should be 12 inches wide and 6 to 12 inches deep. Soak the crowns briefly in lukewarm water before planting. Draw a hoe along each side of the prepared trench to form a mound in the center running the length of the trench. Set the crowns 18 inches apart on the mounds in the trench, draping the roots over the sides. Cover the crowns with a mix of one part compost to three parts topsoil, burying the crowns 2 inches deep. Water the bed thoroughly. After about a month, once shoots have appeared, carefully add more soil to the trench.
First year: Weed the beds frequently, taking care not to disturb roots. Periodically add more topsoil/compost around the emerging shoots until the trench is filled. Then spread a 4- to 8-inch layer of mulch, such as hay or leaves, around the base of the plants. Water regularly. Do not harvest any spears the first year. Cut down dead foliage in late fall and side-dress with compost.
Second year: Cultivate lightly by hand until the new spears are several inches tall. Keep the bed thickly mulched. Side-dress with compost in the spring and early fall. Cut down dead ferns in late fall. You may harvest very lightly the second year.
Third year and beyond: Maintain as for the second year, and begin harvesting.
How to harvest asparagus
Plants started from crowns can be harvested lightly in the spring of the second year. Begin harvesting in earnest the third year. Harvest only those spears that are thicker than a pencil. Cut off the spears at or just above ground level when they are 6 to 8 inches tall.