CJ :One small requirements is needed in the Spring,after the pots have been taken out of ground.
The Drainage holes are now plugged by roots that were cut off but the results are the same.
Drainage holes are plugged.
So:
Remedy:
Drill extra Holes on Bottom side,or:
Loosen the tree from pot,turn it ,90 degree ,and ,fill it with potting soil again.
When turned,the roots usually come out of holes,so the tree is ready to grow new roots that will come out the pot,and find there way in the near ground.