Hi Emily, and welcome to ATP. I live in Florida now but garden in Salt Lake City still, where we lived for 20 years before moving to warmer climes. (my kids and grandkids still are there) Salt Lake is fairly similar climate to you in Calgary, although you may get colder in the winter.
One word for winter prep: Mulch. A good mulch will keep your soil cool and moist in summer, stop erosion, slow down weeds, and keep the ground from heaving and tearing up your plants' roots in winter, too. So you can start mulching now, but don't bury the crowns of the plants until they've died back after first frost, then put another good deep mulch over the whole thing.
I never cut back anything until spring, then just cut whatever had died back during the winter. If the dead stems are unsightly to you, by all means cut them off, chop them in pieces and add them to the mulch - they are made up of what your plants need most!
