I have two Wisteria Brachybotrys, each growing in a 1200 litre tub, on either side of a gazebo. They are young, purchased in the spring, but have already entwined the trellis walls and the roof of the gazebo. They are each some 2.5m tall. The location is southern England and the location is in full sun from mid-morning to dusk.
Looking to the future, I want to know how long these plants can sensibly be kept in these containers before becoming potbound.
The RHS guidelines indicate that container growth is possible but don't indicate a timeline.
If the expected life in pots is only a few years, I would expect to try to transplant them into the ground. To do this would require cutting the plants out of the trellis, which, if I must do, I would want to do soon, before they become too entwined.
This is something of the inverse of this earlier question
Should I leave these plants alone? They're quite healthy and, given the size of the pots, transplanting them will be quite an exercise.