Garden asparagus is a perennial vegetable commonly grown from one-year-old-plants or crowns. Garden asparagus plants require three seasons to achieve full production but may be lightly harvested in their second year. Harvest asparagus spears in spring, cutting just above ground level when they reach 6 to 8 inches in height and are slightly thicker than a pencil.
Asparagus thrives in most soils provided they are well drained. Soak garden asparagus crowns briefly in lukewarm water before planting. Loosen a foot or more of soil and add several inches of compost. Trenches should be a foot wide, 6 to 12 inches deep, and dug 4 feet apart. Form a center mound in the trench using a garden hoe, and place crowns on the mound 18 inches apart with roots draped over the side. Crowns should be 4 inches below the soil surface.
With first year asparagus plants, weed often, avoiding roots. Periodically spread topsoil and mulch. Water regularly and do not harvest. Cut dead foliage in late fall. Second year plants can receive mulch when they are tall enough. Fertilize well between rows. Harvest lightly if at all. In the third year, cut back ferns and remove mulch and fertilizer. Harvest when ready, leaving some spears to grow into ferns. After final harvest, pull weeds, mulch, and fertilize.
Garden asparagus plants should provide harvests for 15 to 25 years. To store asparagus after harvesting, place spears upright in 1 inch of water and keep refrigerated.