I grew up in an area where asparagus was grown in big fields. My dad grew it in his garden 30 years ago. It's a great plant and I love to eat asparagus with potatoes, cooked ham and melted butter. Some like it with sauce Hollandaise.
You need a sandy soil and for a harvest worth wile you need at least 900 square feet or 100 square meters. And, as moyboy said, you need a lot of time. After planting it it has to grow three to five years without harvesting anything. As soon as you grow it for harvesting you pile up "beams" ("beam beds") of soil 1 to 1,5 feet high with a path between the beams (German: "Spargelbalken", "Balkenbeet") in early spring. About beginning to mid of may the first tips of asparagus peep out of the soil. You then dig along the stem with two fingers of one hand and cut the stem as deep in the ground as you can reach it with a long knife. Then you close the beam again with a trowel. In Germany traditionally June 21st is the last day of harvesting asparagus. After that the plants are supposed to grow out until fall. Then you cut down the plants, compost them and wait until next spring. I don't remember exactly how long asparagus plants are good producers. But it's only a few years.