I don’t know for sure, but I am going to split one of mine after it has finished flowering. In the past I have just sliced a wedge of it off with a lawn edging tool, and this bit rooted well. I think I did that after flowering. My main clump is now too big and the rhizomes have risen up in a mound because they are too congested. This patch is in full sun, which is not the best lace for lazica - my other piece is in a damp spot in dappled shade and looks much better there. If only the slugs were not so fond of the flowers.....