Root Pruning shrubs in pots

twopenny

I've heard about it, seen it and looked on the net and it looks straightforward.

But it's scarey not wanting to kill a favourite plant and I wondered if anyone has any advice, hints or tips please.

I have a Magnolia Stellata and a conical Bay tree. I can't accommodate them in the garden or pots that are any bigger.

  

There is also a lilac in a pot I might be able to go larger but the problem would be watering an enormous pot throughly as it gets no rain in the location  so not sure where to go with that. It currently has a pipe in the soil to take water to the bottom.

goldfinches

I've seen these pots recently in one of the college gardens Air-Pot® – The Experts’ Choice 



and here they are in one of the photos I took that day.

I generally get the strong impression that these pots are now used so that professional gardeners can avoid the difficulties and risks of root pruning because it is so much easier to simply pop the plant into this type of pot and think it will look after itself provided you keep it adequately watered. 
I don't think I'd feel at all confident about tackling either of your two trees alone because of the sheer physical difficulty and the danger of damaging them above or below soil level.
So, I don't really have any suggestions except maybe invite @Davesnave round for the day.

theoretica

goldfinches said:

I've seen these pots recently in one of the college gardens Air-Pot® – The Experts’ Choice 

I generally get the strong impression that these pots are now used so that professional gardeners can avoid the difficulties and risks of root pruning because it is so much easier to simply pop the plant into this type of pot and think it will look after itself provided you keep it adequately watered.

That is the key point - I gave some of those pots to my mum to try - with all those holes the soil dries out really fast and you need to water much much more often.  Great/fine if you have an automatic watering system.

The thing to remember in root pruning is you want to chop the big thick roots and leave the small ones alone - so tempting to do it the other way.  But I would only do any if I am repotting anyway, every few years, and the plant is root bound.  Do you know how rootbound they are?  How long have they been in those pots?

twopenny

I've repotted this autumn

twopenny

I've repotted this week so the Bay has an inch or so and the Magnolia a couple of inches at the bottom. They should be ok till next year but I'm planning ahead as decisions will have to be made this year.

The Lilac I still have to tackle but it will be compost on top or repot. It's grown about 2ft a year. It's the tough old original strain from a sucker which I intended to throw out but gives shade, privacy and a feeling of nature in my somewhat exposed bedroom.

In fact the pots have cost more than the plants!