Planting asparagus in the fall? Help

I just moved and am starting from scratch. My local nursery has about 20 asparagus plants in pots that they are giving me a deal on. All planting information I can find states planting crowns, the plants I am buying are in the fern like stage. How do I plant these? Do I dig a 6 inch trench like for the crowns or plant like a normal plant? Please help

I would suggest maintaining them in the pots until the ferns die back, then the plant has already removed the sugars as much as possible from the upper portion. Then plant the crowns.

Like Tj says, leave the plants alone for now, once the ferns die back you can trim them and lift the crowns to plant per the crown planting instructions.
Do remember that for the next two years you won't be harvesting any asparagus spears, this is so the crowns can get well established and produce for you for around the next 20 years.
The third year you can harvest some, but not all of the spears (you always want to stop harvesting so the crown can be replenished by the ferns for the next years harvest).
Every year after year three you can harvest more and more spears, leaving the last sprouting to do the replenishing of the crowns.

I was looking at this thread with interest because in July my wife called my attention to a Walmart clearance sale of some bagged asparagus crowns that were entirely dried out and very very dead-seeming for $.75 per bag of 4-5 crowns per bag.  I was very skeptical that the dried-out crowns had any life or that I could bring them awake in high summer, but she was interested and the price was right and so I bought about a dozen bags and planted them densely in three of my container-garden containers made from old insulated plastic coolers.  (To not waste effort and water I also surface-planted the containers with cilantro.)  

Damn me if I didn't get a dense stand of asparagus and cilantro both by mid-August, which has been happily co-habitating (given the tally wispy frondy growth habit of the asparagus) ever since. (Although the cilantro is getting pretty bolty by now.) My assumption has been that I would let the asparagus grown until the fronds died back, then root the crowns out of the containers and fall plant them into a permanent bed, but I was very much guessing.  It's nice to see that confirmed.