I like raised bed gardening because it is so much easier to weed and to apply mulch, compost, and fertilizers and maintain the balance you want in your garden. I did not know you could grow asparagus in one though. I love that you can since aparagus once planted is going to be there for many many years I think a raised would be perfect for it. Homeguidessfgate shares how to plant it in a raised bed.

http://homeguides.sfgate.com/grow-asparagus-raised-beds-40588.html