Asparagus is a cool weather (Zones 4-9), perennial vegetable that takes 2-3 years to produce a harvest. However, patience is rewarded by a crop that may last 20 years. 

Asparagus seed should be sowed in light sandy soil, early in the spring. Seed 2 to 4 inches apart 1/2 inch deep, in 15 to 24 inch rows. As asparagus germinates slowly, mix in a few radish seeds to mark the row for early cultivation. Roots may be transplanted either the following spring or left in seed bed for two years. Transplant 18 to 24 inches apart to trench 8 to 10 inches deep and wide enough to spread roots out evenly around crown. Cover with 2 inches of soil, packed tightly. Gradually fill the trench as the plants grow. Rows should be 4 feet apart. Rotted manure may be used in bottom of trench. Minimum soil temperature of about 50 degrees Fahrenheit at a 4 in. depth.

From our 1902 catalog: One of the earliest spring vegetables, of excellent flavor, taste much resembling peas, but as it becomes more generally known is much preferred to peas by many. It requires a deep, rich, mellow soil. Sow early in the spring in drills 2 inches deep and 12 inches apart if to be cultivated by hand. Mine are 24 inches apart and thus are easily worked with a. horse, and this also gives the plants a better chance. One ounce of seed will will make about 600 plants. When the plants are one or two years old (one year is best, as a better crown will form) transplant to rows 5 feet apart and 18 inches apart in the row. Cover the soil 4 to 5 inches deep with well rotted manure and disc well, then plow as deep as possible and fine with the harrow. Then with the plow turn furrows 5 feet apart, about 6 inches deep. Place the plants in these about 18 inches apart, one in a place and with the roots well spread out. Then turn a light furrow back over them and level with the harrow by cross harrowing. If the soil be dry and you have water, after you cover them run water through the furrows before leveling. Give the surface a good dressing with manure each year. Cultivate often.

Good companion crops for asparagus are basil, parsley, tomatoes and marigolds. Bad companions for asparagus are garlic, onions and potatoes.