with Dave, and I'll add:
Once the late season rains start and the soil is moist but not wet, I usually start planting perennials first; smallest root-balls before the larger ones. The smaller ones usually need the most time to settle in. Once those are all in, I start planting shrubs and trees.
If your area doesn't receive a lot of snowfall that sticks around, mulching these new transplants would probably be a good idea; especially through the late winter thaw-and-refreeze cycles.
to ATP!
