Asparagus is a long-lived perennial that will provide you with tender spears for years to come if you take the time to prepare a bed and plant the dormant roots in a suitable site. You can amend the soil to a degree, but you must make sure that the site has good internal drainage or the roots will be susceptible to disease and rot. Early spring is the time to plant your dormant one-year old roots, when the soil is warming up from winter.
Pick a spot in your garden or yard where you can grow the asparagus. It needs to be an area off to the south side so it will not block the sunlight from the garden in the summer when you allow the ferns to grow. You also do not want to be doing any tilling in this area since the roots are just below the surface. Plan on a spot where you can leave it for the next ten years.
Prepare the asparagus bed by digging up the soil to about 6 inches deep. Work a good amount of well-rotted compost into the soil. Asparagus likes alkaline soil, so you can work in hay or straw mulch as well as bone meal or wood ashes for a good boost for the roots. Drag 6-inch deep furrows in the bed with a garden hoe, in rows 12 inches apart.
Plant your asparagus roots into the furrows, keeping them 12 inches apart from each other. Pull the soil in over them and tamp it just slightly with the back of the hoe. You do not want to compact the soil or the new shoots will have a harder time working their way up to the light.
Water the area so that it gets soaked at least 6 inches down, immediately after planting. Keep weeds handpicked from the bed, adding straw mulch as needed to keep the weeds under control. Further watering should not be necessary if the soil has plenty of organic matter incorporated.
Allow the first year shoots to grow unhindered. Do not pick any spears from the young plants, as they need the ferns to grow and collect nutrients for the developing root system below. The following year, you can pick them lightly for about two weeks, snapping them off at ground level. Allow the ferns to grow again into the winter. The next year, you should be able to pick for several weeks without hindering the growth of the plant.
Mulch the bed in the late fall with a 6-inch layer of hay/straw mulch after you have cut back the dried ferns.