Acer tataricum ssp. ginnala grafts

Back in yearly spring 2009 I did two thread grafts on this tree.
It looks like the holes that I drilled have close nicely, but I am not too sure if the cuttings can actually survive on their own just yet.
Could it be that Finnish growing season is not long enough to do this kind of things in 1 year?

Here is the tree today. For some reason this tree has never given me nice fall colours. Don't know what I am doing wrong. Maybe I give it too much nitrogen. Any tips would be welcome. :)