Two days after reinstalling our quick hoop, the soil temperature underneath the protective fabric was already four degrees warmer than soil temperature on a neighboring bed!  Granted, I had raked back the mulch on the neighboring bed just like I did on my quick hoop bed, but hadn't applied juicy, warm manure, so it's possible the manure application is part of the reason for my fast soil heating.

Truthfully, though, I don't care if it's the quick hoop or the manure that kicked my soil temperature up to 36.  I'm just thrilled that it's finally warm enough to plant my first lettuce bed.  Fresh lettuce in four weeks if all goes well!