Gritty mix and root pruning?
First of all, I want to give a big shout out to Al for the 511 mix! I used it for my first time vegetables this year, and had great results. Even was able to get five cantaloupes from 2 4gal pots.
Anyway, I was considering moving a few trees into the gritty mix. They are sweetbay magnolia which reside in built in brick planters, 4x4x4.
I know that I will need to root prune them if they are to last a long time. But I can't find anything specific to these type of trees. In my area they keep their leaves all year. (zone 7b, Memphis) I mentioned root pruning to someone at a local nursery, and they said that the sweetbay would probably die if I go that route. However, these planter also house my pool descents, so I have to either root prune or pull them out before the roots can become a problem. Which would probably mean I have a max of 8 years left. And I would like them to have a long beautiful life where they are.
So my question is, when can I root prune these, and at what outcome? Will they lose their leaves? How often to root prune?
On a side note, I want to put some boxwood topiaries into some planters. Do I root prune prior to transplanting? Should I wait until fall? Spring?