If its finished flowering then it will benefit from a trim to keep it tidy and compact. If it has yet to flower then wait or risk no flowers. I find with my Sedums I dont actually split but take rooted pieces from around the edges either to contain them or grow on.

Agree with Drc I would not consider giving a sedum a proper Chelsea Chop tidy up the deadheads if it has flowered and later in the season you'll be able to remove rooted pieces from the outer edges. Out of interest which sedum do you have?

If it is sedum spectabile, then I would say no it,s not too late, I reduced mine by about 1/3 ten days ago and am already seeing new growth from the leaf joints, so chopping them now will not make a lot of difference, maybe a week or so later flowering, you can also propagate them at the same time, any pieces you cut off, just push them into the soil, and they should root easily, Derek.

Many thanks for your swift responses! It's a Sedum Spectabile Moongrower; I thought they were supposed to benefit from a chelsea chop at the end of May/beginning of June to prevent them becomming too leggy. Hence my question. But now I'm confused...

Thanks very much Derek. In that case I will give it a go tomorrow!

Ah what, as a child, I knew as an 'ice plant'. Certainly one of the more thuggy sedums but I still wouldn't try a Chelsea chop on - these are succulents.

I didn't know what is meant by the "Chelsea Chop" so I looked it up and the BBC described it for me!

One of their examples was Sedum........see here;

http://www.bbc.co.uk/gardening/basics/techniques/pruning_pruningflowers1.shtml

The RHS says that the chelsea chop is suitable for amogst a few others, the larger robust sedums Moongrower and their examples look good. So I'm going to give it a go anyway. I just wanted to know if it was too late.

Do let us know if it works Digginfit, our sedums are all low to the ground and in general well behaved.