How much snow do you have on the ground?

How cold is it expected to get?

tj

No snow, single digits.

I can't speak to zone 7, but up here the reason to protect rhodies and broadleaf evergreens is from wind damage and reduce transpiration. You mentioned they're new transplants -- generally speaking, a thick layer of mulch prevents heaving from the freeze-thaw cycle something to be concerned about with new transplants, so putting down mulch around the bases would be good idea, if you haven't already. If you'd like to take an extra step, you can fashion some sort of cage around them and stuff it loosely with straw - that way you'd get the benefit of wind protection, too. But, if they're not in an exposed area, that might not be necessary.

How cold is it expected to get?

Overnight tonight for us it is predicted to reach a low of -21C/-6F....with very little snow cover :(.