Trimming roots of bigger plants in pots?

[Vodkacranberryplease]

I've got various plants that have been in pots since I got them and I really need to keep them in said pots as they are the biggest I have. But they aren't doing very well and the pots are filled with roots (especially the hebe and jasmine)
Is taking them out, trimming the roots, putting fresh soil in and re potting them an option? If so when is best?
I have nowhere else to put them so would be great if I could do this.
Included in this is
A big Hebe (re potted one earlier this year snd has to massacre the roots to get it out - now flowering)
A honeysuckle lonicera heckrotti (45cm sq pot)
A star jasmine (45cm sq pot)
A large Phlox paniculata
A large viburnum
A climbing rose Madame Alfred Carrere (45cm sq pot)

None of the pots are stupidly small. If I really had to I could buy bigger square pots for the climbers I guess I am just worried that they will promptly fill those up!

It's not really the best time of year to do it, unless you reduce the tops by a similar proportion. Otherwise they won't be able to take up enough water to supply all the top growth, and they might keel over and die before they get the chance to grow new roots.

Around March would be best, if the weather is mild, or alternatively late September, which will still leave time for them to grow new roots before winter.

Just thought of another thing, have you given them a dose of vine weevil killer?

They could probably all do with some tomato fertiliser once a fortnight until the end of August. It doesn't just work on tomatoes.

In general, if you're growing for foliage use a "balanced" general purpose fertiliser, if you want flowers or fruit, use tomato fetiliser.

I've been using tomato fertiliser - I only just bought it last week! On dahlias, begonias, petunias and the jasmine which now has a very few flowers.

Ok so I will hold off and do it in sept and March - I did my other hebe in April or so and it's flowering now plus I need to work out how to prune the bigger one.

Also I've just checked and I can divide my Phlox! So I'll do that in autumn/spring