My British gardening book says to divide them in late summer or early spring - presumably, early spring means something different where you are than it does here in London - late March rather than early March, maybe?

My book says divide after flowering in early spring or late summer. If you wait until they have flowered it will be the right time for your area.

My books say much the same, but has anyone actually done it then?

I've just had a look at the RHS info on these - they certainly do not say anything about their disliking being moved or disturbed, and echo the advice about dividing either late summer or early spring, except for 2 varieties. The one you have, Owdboggy has a note that specialist growers prefer to divide this particular one in late summer rather than spring because they feel it gives better results.

I have divided hybrids in the past, dusted the break with green sulphur with only a 50/50 success rate which proves they are better off left alone. If you would like any seedlings of the green ones H. Argutifolius Viridus, I will send you some if you PM your address to me. Best planted in an area on their own as they self seed every year like mustard and cress.

They don't like being moved at all. Cuttings will work but don't expect flowers for 2-3 years. Have tried this. Eventually there is success, you just need time and patience. Cuttings replanted 3 years ago in Hatfield, Worcestershire, are still just leaf and just showing flower buds now. Worthwhile in the long term, but for instant success you cannot beat the garden centre!!!

I am not really in the market for new hybrids, we have probably near 300 plants as it is. I have 2 plants of the one I really want to spread out so I may try dividing that one, or not as the case may be.
H. argutifolius is certainly a prolific spreader by seed. Now if H. purpurascens or H. thibetana were as good,,,,,,,,,,sigh.

Cuttings and patience it is then ... ... Once you get started with the cuttings it will be easy peasy every year! I gave up following the first lot - no hassle involved and very easy to take care of, it was just the time-scale!

Well I have just been reading the Elizabeth Strangman book and she and Graham Rice say that the Oriental hybrid types should be done in late August early September as this type grows new roots over Winter. They go into great detail as to how to do it too. I think I will give it a whirl then. Must remember to mark the plant I want to propagate since the flowers and seeds will have gone by then.

Go for it, owdboggy! Best wishes with your project ...

The thought which occurred was that places like Ashwoods and Farmyard Nurseries who specialise in Hellebore hybrids, must propagate by division to get the numbers of identical colours. From seed the variations are immense and sadly many are not worth the effort. There is no way that a commercial operation could afford to operate on that basis.