This post has a little more detail about growing asparagus then the last one.
When growing asparagus choose a site where your plants won’t be disturbed, and where you and they can happily coexist for 10 to 15 years. Grow asparagus in partial or full sun (does best in full sun) in soil with a pH of 6.5 to 7.0; be sure to use plenty of organic matter that is rich in potassium and phosphorus.
Buy asparagus crowns (established root systems with dormant top growth) at your nursery or though a catalog. In cool regions, plant them in early spring when the soil temperature has reached about 50 degrees. In warm regions plant in late winter.
To prepare the soil for planting make a 7-inch deep V-shaped furrow (or more, depending on how many crowns you’re planting) and in each one a handful of wood ashes, a handful of Bonemeal, and an inch layer of compost or well rotted manure.
Soak the crowns in compost tea for about 10 minutes or so and lay them on their sides on top of the organic matter, 12 to 16 inches apart, in rows 4 feet apart. Fill in the furrows gradually as shoots emerge, taking care not to cover any foliage, eventually the furrow will be level with the soil surface. Don’t bother spreading out the roots, they will find their way down.
Weed regularly and mulch heavily with chopped leaves or straw after you have filled in the furrows. Side-dress plants with a balanced organic fertilizer in the late summer, and top the bed in organic mulch in the fall.
Give new plantings one to two inches of water a week, after that water only when rainfall is scant. Refrain from harvesting any spears during your plants first year in your garden. Each spear needs to develop so that the roots can grow stronger and more productive. The second year you can pick a few that reach the size of your index finger. The third year pick finger sized spears for two to four weeks in the spring. In later years take all the finger sized spears you want for six to eight weeks, or until the spears that come up are thin and spindly.