To grow asparagus, plant 1-year-old asparagus plants in the ground outside as early in the spring as possible, once the soil is no longer frozen. Before planting asparagus, weed the area; dig the soil over; and mix a 2- to 4-inch layer of compost, soil mix or manure into the soil in the bed. In the soil, make trenches that are about 6 inches wide and 6 to 12 inches deep.
Place young asparagus plants about 15 to 18 inches apart in the trenches, with the roots of the plants along the ridge. After all the plants are in place, put about 2 inches of soil to cover the plants, and water. Because asparagus needs soil with good drainage, use raised beds to improve soil drainage if necessary.
While the plants are growing, add soil frequently until the trenches are full, but always leave about 3 to 4 inches of the stem uncovered. Once the trench is full of soil, place about 4 to 8 inches of mulch around the plants. Remember to water asparagus regularly.
During the first year of growth, get rid of dead foliage at the end of the fall instead of harvesting asparagus spears. After the foliage is gone, side-dress the plants with compost. In the second year of growth, make sure that there is plenty of mulch covering the soil all year. Side-dress the plants with mulch in the spring and the beginning of fall. Get rid of dead foliage at the end of fall, as you did the first year.