I recently acquired a collection of trees that the owner was unable to maintain. The worst suffering had not been repotted for some time, to the extent that the drainage holes are occupied with roots almost as thick as the hole itself, and drainage is non-existent. In the canopy, branches have been lost and growth has been extremely limited for at least one year. The trees were inadequately watered and though I can’t be sure, I’d say haven’t been fertilised for a long time.
Common advice is to slip pot into a larger container without doing any root pruning. But I’ve been bitten by that in the past with conifers.
Does there come a point where a tree is so badly in need of repotting that it is too weak to be repotted?
Should one perform a very conservative repot - simply aim to free up the drainage holes and remove any dead matted roots from the bottom, so that water/oxygen can drain/enter the system (respectively)?
Should one avoid repotting completely for a season and instead use the various techniques for improving percolation and water removal in the hope the trees can regain enough strength to survive a repot?
The species I’m concerned about are western hemlock and japanese larch. Broadleaf species that were in the collection I am more confident to handle.
Any advice appreciated.