Hole's Greenhouse in St Albert has a large selection of perennials. I think they have some alpines. There are several good garden centres in the area. I'd suggest calling around when you get to Edmonton.

You must check out Wellington Garden Center just off St.Albert Trail.. It is a wonderful place. Here is the address and they also have a website. Have a wonderful trip!!
Wellington Garden Centre
13648 - 142 Street
Edmonton, Alberta
T5L 4Z2

T: (780) 455.2281*
F: (780) 447.4741
E: info@wellingtongardencentre.com
http://wellingtongardencentre.com/index.htm

Greenland Garden Centre is the very best in town for service and price. Holes and wellington are just too darn expensive.

greenlandgarden.com

I think they are all too expensive, or maybe I'm too cheap. However, I like Walmart, Superstore and Canadian Tire. At the end of Summer, early fall you can get some pretty good bargains. The only time I would get anything from a Garden Center is if I need a tree/roses on own roots/some evergreen shrubs. With trees you get what you pay for, and also roses on their own roots.