Asparagus is one of the few perennial vegetables that can be grown in most home gardens successfully. The edible spears are harvested year after year, and the fern-like appearance of the plants in late summer is attractive in many ornamental gardens. Asparagus usually is planted from purchased transplants, allowing you to harvest your first fresh spears in as little as one year. Planting asparagus crowns requires minimal work to ensure up to 20 years of harvest.
Lay a 3-inch layer of mature compost over a full-sun garden bed that isn't prone to standing water. Add ½ lb. of complete 10-20-10 analysis fertilizer per every 100 square feet of bed. Till the compost and fertilizer into the soil to a 16-inch depth using a spade or power tiller.
Dig the planting holes 10 inches deep and 10 inches wide. Space each hole 18 inches apart in rows also spaced 18 inches apart. Set the asparagus crown in the hole, spreading the roots out and around the crown. Cover with 2 inches of soil.
Lay a 2-inch layer of organic mulch, such as wood chips, over the entire bed to help preserve soil moisture and to prevent weeds. Water the bed once a week, providing about 1 inch of water. Keep the soil moist but never let it get soggy.
Cut off the tops of the asparagus in fall once they have browned and begun to die back, often after the first frost. Do not harvest spears the first year. Mulch over the bed with a 2- to 4-inch layer of straw mulch to protect the asparagus crowns over winter.
Remove the straw and apply a fresh 1-inch layer of compost over the bed in spring once the spears begin actively growing again. Harvest the spears by cutting them off at ground level when they are 6 to 8 inches long. Harvest until mid-summer, then allow the spears to leaf out for the rest of the season.