There's lots of interesting and rather unknown trees and shrubs capable of thriving in zone 3, especially if provided with a protected location. Friends of mine have planted an acacia, I have not seen this in bloom, though they say it has wonderful very long clusters of a pink/purple. Considering the open windy location it's sited in, I'm surprised it has lived, let alone flowered! Years back, I had seen a katsura tree (probably about 20 ft tall) in someone's backyard while attending a plant exchange in west Edmonton. The tree has very nice small heart shaped foliage. Unfortunately, I do no not recall the location and also have never come across Katsura available from any nursery here :(

For several years I had grown a 'Prairie Silk' honeylocust. Any new wood that was gained, this was always killed back to the trunk, the tree had added no height in seven years. It was not planted in the most ideal location and neither was the soil all that particularly good. I will try the tree again in my protected backyard, the soil is much better here also :)

Katsura photo

http://www.flickr.com/photos/myriaddesign/3930299595/

Terry

Here is a link that might be useful: Katsura