So, I've never known a thing about asparagus until I read Animal, Vegetable, Miracle and read about this family that lived for a year on all local or homegrown things. And I thought, wow...a perennial asparagus plant would supply our desire for garlic roasted asparagus and asparagus soup.
So, I looked into it and planted an asparagus plant recently. And because we bought it mature, we've already been able to harvest one spear (though they can grow up to 6 inches in a day if you don't watch them--like this one grew four inches before I realized I should've cut it the day before).
In case you're unsure of how it works, you generally plant these dead looking long roots that look octupus-ish in a 12 inch deep trench and barely cover, then water. Each day you add more soil until it's back to ground level. They start shooting spears out of the ground. You cut them when 6-8 inches tall and 1/4-1/2 inch think. But don't cut the thin ones, because they either are the male spears that haven't gotten big enough this year, or the female spears that pollinate the other. So leave those all to reseed this fall and you'll start having a "weed patch" of lots of asparagus.
Be patient. These plants are perennial and will produce for up to two decades generally, but they take about 3 years to really establish most of the time (except we bought ours already 1-2 years old, which helps. The crowns are just a few bucks and since they proliferate you don't need many. But plant them in full sun, good soil (with extra phosphate and good drainage). But they love water, as long as they don't sit in it and get root rot. And they normally just are harvestable in spring for a few weeks.
So, hopefully it will keep growing well and be a faithful garden keeper and mulitplier. :)