You will have to trust me on this one that the roots I have dug up will grow. It’s a lovely plant and it’s no trouble at all, the slugs and snails seem to ignore it. It will spread slowly and come up every year. All I do is cut it down at the end of the year when it seems to be finishing. The first picture is in my garden, it’s the one with the white spikes. Mine is grown in full sun. They die down and come up in the spring. As you can see, it is dormant at the moment.
Ready to plant right away.

White Lysmachia roots (Morden SM4)