You could get them into larger pots right now with the addition of gritty soil around the whole ball, no need to fuss about roots otherwise til either of the two times you mentioned.

Thanks Lucy
I have already put them in larger pots with soil around the root ball but still would like to know the best time to root prune and transplant and anything else that will help them survive a drastic root pruning.
Paul

I thought you made two good (time) suggestions that I agreed with... Once you do the job, keep them in filtered sun or light shade for a few weeks and well watered. Maybe someone else will have more ideas for you.

I will do as you suggest; It's the drastic root pruning that is needed that's bothering me.
I would hate to lose the trees.
Paul

With a root bound plant it is critical that water gets all the way into the root ball. When watering right now, completely submerge them in a pail/container of water until they are totally saturated (wait 5 minutes or until bubbles stop coming up). Then remove and let the plant drain. Repeat when the surface of the soil is dry.

You will want to repot in early Spring. If the plants are as rootbound as you describe, most of the roots will be dead anyway, so it's not like you are cutting healthy roots. Soak the trees thoroughly beforehand, then completely untangle the rootball, cutting long and dead roots and removing ALL the old soil. When repotting you will want to make sure the tree is well anchored so that new fragile roots will not be irritated by the tree moving.

When repotting don't forget to cut back the foilage hard - with fewer roots the tree will not be able to sustain as much foilage. Always remember to balance roots and foilage.

Finally, leave the tree in shade for at least two weeks after repotting and only gradually return it to full sunlight after you start to see new growth. Do not do any other training or repotting work for at least one season.

Alex

www.bonsainut.com

I really don't agree with a few things you said here - assuming most of the roots will be dead - that's just not a given, nor necessarily expected at all. Certainly he'll need to do some serious work, but wholesale chopping is not recommended just on the principal of an assumption. I also don't necessarily think he needs to submerge the trees now or later - just being attentive to frequent watering is needed. And, the business about cutting back foliage to (presumably) balance the root system is really old hat - it just doesn't hold up and people like Brent Walston of Evergreengardenworks and others don't do that anymore.