This is the front welcome garden viewed from the house. Although I call it the "established side" of the front garden, it was only finished 2 years ago and still has to fill in a little in spots. This view was calling for a little something extra so this morning I grabbed some short, orange asiatic lilies from a spot in the back garden (where I had always intended to move them from anyway), and plunked them in here. They sure brighten things up, don't they?
The general rule is to move spring-flowering perennials in the fall, and fall-flowering perennials in the spring. The reason for that is that if you move plants close to their bloom time, they will be putting energy into blooming rather than into establishing their roots in their new home, and thus the plants may suffer.
Bah! Suffer, shmuffer! Once you have some experience in the garden and know which plants are super tough, go ahead and experiment. I've moved plenty of plants against the rules (I also just moved a dianthus in bloom and this spring I moved bleeding hearts, for example). That said, some fussier plants might not do so well or they just might not flower as well this year. I'm sure there are a few plants I've moved against the rules and which didn't do so well, but sorry, I can't think of them right now! I generally don't grow fussy plants anyway.
I sure like moving perennials while they're blooming or at least while they're at full size for the instant gratification you get! This wouldn't have been nearly as fun if I'd waited until fall to move those lilies.