Is it too late to divide perennials? I started to dig up my veronicastrum a month ago but was defeated by an unexpectedly huge rootball which I needed help for & didn't get so I covered it back round again.
If I do manage to get it out of the ground, how small should the clumps be after dividing & how far apart should I space them? would they benefit from some bonemeal?
I would still do it now as soil is still warm here anyway while plants are dormat !
But get a move on
As to when, the broad rule is that perennials that flower in the first half of summer (ie before the end of July) are divided in autumn - allowing them plenty of time to recover. Similarly late-summer or autumn performers aren’t divided until spring. Split them just when as new growth is beginning to get going.
Thanks - I finally did this in February eek as I had no help and it was a huge weight. I had to just dig a hole where I wanted it to go & drop it in to fit. It has got new shoots on it now, a good 4" high, but then it was a simple 'move' in the end rather than tearing it up. Although that's still going to have to be done at the next window I feel.