I am landscaping an area in my front yard about 8x8 feet. My front yard is elevated from the sidewalk and retained by a 3' tall fieldstone wall. The area gets about 5 hours of morning/afternoon sun. I want to plant a JM as a focal point, and I was thinking of a 'Garnet' or 'Crimson Queen'. Looking at the spot from the street, the area calls for a tree that is about 5ft tall and wide.

Unfortunately, the trees in that size are out of my price range, so I found ones that were about 3-4' tall, but somewhat sparse in branches. How much growth can I expect in the threadleaf varieties? Is it possible to plant the tree in a large containter above ground for a few years until it gets larger? I live in zone 5/6, we get a good amount of snow and cold!!