For freeze hardy plants the magic combination is 40 degrees of soil temps and 6 weeks to let the roots grow. Once the soil dips below 40 degrees, the roots stop growing. This is, of course, just a general guideline. For my zone 5 the magic date is around October 15-20, for your zone I'd guess (only a guess) you're about at the limit.

tj

I'm in zone 4, it's been as cold as 16 degrees...and I'm still planting/transplanting perennials. I still have some 'clearance' shrubs on the porch, I have to finish planting, this afternoon!

If your perennials are okay until spring, you might want to wait, but if your area is like mine (lots of clay) it's easier to move them now, then waiting until late spring, when the ground is finally dry enough to dig. Start too early and it ruins the soil...clay is wonderful to grow in, but it's slime in early spring and cement in the summer, unless you water a lot :)

Hmmm...I think I need a soil thermometer. Thanks for the advice!