How many dogs does it take to move a greenhouse?

Just one...

(plus 5 human helpers)...
After stripping it down to the basic frame, and prying it off the earthquake-proofing rebar and pins, we moved the greenhouse from here:

to here:

to here (which is apparently the perfect spot for a supersized dog house) :
to here:
Which, in hindsight, is where it should have gone in the first place... except there were two trees, a large bush and a bunch of perennials there. 

So, "move greenhouse" is checked off the to-do list (along with "demolish the playhouse"), which just leaves "tear down the shed".