Hi Jennie...spend some time at the Bluestem.ca website linked below. They specialize in ornamental grasses for cold climates. Start with the comparison chart, which will give you sizes, habits, culture and hardiness. Then it will lead you back into fuller descriptions and numerous photos for each grass.

Here is a link that might be useful: Bluestem Comparison Chart

Jennie,
You might try checking out a previous post titled grasses in zone 3/4. There were some very helpful replys posted there
a.

Here is a link that might be useful: grasses in 3/4