if things are too big for the space.. just get rid of them ...

dividing is not really an option.. in most shrubs ... but regardless of that.. given a few years.. you will be right back to the same monsters taking up the given space ...

dig them out... or cut flush to the ground.. and apply stump killer or round up to the cut stumps ...

but before you do.. google REJUVENATION PRUNING OF FLOWERING SHRUBS .... and see if you want to try just cutting them down.. and then annually following that program ...

one system involves a lot of work.. and be done with them ..

the latter involves a lot of work now.. and work every year after.. forever ...

and at that point you are back to my first line ... lol

ken

Late last winter, I thinned my Spirea with very good results. I simply chopped out the oldest branches at the base. It sent up new sprouts both at the base and on remaining branches. I do this with most of my bushes to keep them from growing out of control and taking over.

DO NOT TRIM bushes in the fall. It will stimulate new growth that will be killed of if you have cold winters. Wait until late winter for all pruning.

I inherited a bush and when it was dug up, it was discovered that the base had separated in two and we planted them separately. So, yes, in a strange sort of way, they can be divided....

Depending on how much root you can get with each part, you can chop the base but this will be a bare root transplant and take a bit more care to encourage it to live.