established potted climber...how

Something thats always puzzled me. How do you care for the roots of an established climber living in a pot? How do you repot it without damaging the stems/branches that are attached to whatever its growing on (assuming its growing on a wall, pergola, arch or something that can't be moved)

i had two clematis which lived in large pots but they were growing up a wigwam of bamboo canes so it was possible (although very awkward) to repot & do a little root pruning but.....i dont know what to do with my Nelly Moser Clematis its been growing in a large-ish pot for quite a number of years now, its growing up an arch which is clad in green gardening mesh (the clematis is well entwined with it at this point) well poor old Nelly is suffering & desperately needs repotting but....how do i repot it without damaging it or the arch?

What do you guys do?

Edit: ok so i screwed up the heading & i dont know how to change it lol

 

You could simply try removing the top couple of inches of compost and replacing with fresh.
Or hopefully the arch could support the top growth then one person could support the lower stem and take the weight of the plant while the other manoeuvres the old pot off and the new one on.

 

I just moved two established Clematis into taller planters this February. I do think Clematis perform better in an approx 18" deep planter . I cut them back to about 2 feet long then repotted in a mix of soil , mpc and sharp sand. Trimmed them back to the lowest bud in March. They are growing really well now.
Maybe not the answer you need if you are trying to repot them without cutting back. Nelly Moser is a group 2 (see below)so could be cut back to 1 metre . Not sure this is the right time - maybe our clematis guru's can advise.

Group 2 (light) - are the large-flowered varieties that begin to bloom in May or early June with the first flush of flowers appearing on the previous year's growth, followed by a smaller flush on new growth. Pruning should consist of cutting shoots at a height of 100 - 150 cm from the base (the younger a plant the lower it should be cut). This is a safe way of pruning if we are unsure which category our plant falls into.

 

Thanks nigel & harry. All the new growth is right at the top & what with it not looking the healthiest im reluctant to cut back too much into old wood as im not sure poor old Nelly would recover tbh. Im thinking i may cut the green mesh completely off the arch and attempt to go over it inch by inch cutting the wire to free as much of Nelly as possible. I'll buy new green mesh to clad the arch.

Is that what people do with large pots that cannot be repotted? Does it stop plants becoming rootbound? Nelly is beyond this now (shes severely rootbound) but perhaps if I'd done this annually she'd not be in the state she is now?

 

@Ian Taylor may have some thoughts on this. He has quite a collection of Clematis.

 

Update if anyone's interested lol Well, last year i dug out as much compost from the top of the pot as i dared, cutting my way through roots as i went along. I replaced with my own compost mix which must've been quite rich cos poor old Nelly responded wonderfully! She put on lots of new growth very quickly & even managed to put out a few last minute flowers in late Autumn! growth this spring already looks very healthy & vigorous too! thank you @NigelJ