Not heard of these so looked on the RHS site, which says best sown in situ in spring.

Thanks Stera - it's difficult to know what to believe sometimes, isn't it. Luckily I've saved half the packet, so can do both, but SR is not so helpful on aftercare!

Good luck anyway. Apparently its related to Bishops weed aka ground elder.

A lot of things are related to Bishop's Weed, Stera--carrots, celery, dill, etc. I guess that every family has a black sheep! Bishop's flower (Ammi majus) isn't nearly as persistent and invasive as Bishop's Weed (Aegopodium podagraria).