In my climate yews should be repotted around end of April. But slip-potting is OK any time. This means just taking the tree with full root ball totally intact and place into a pot without disturbing. Anyway, it worked very well. The explosion last fall was bad when it happened. One can still see some brown branches. But they all have enough new buds. So in the end nothing happened. Now the tree will have to settle for a year. in 2013 it will be styled finally. I will report.