Can you tell me about the spread of Ranunculus ficaria ‘Green Petal’?
The Royal Horticultural Society’s A-Z Encyclopedia of Garden Plants (ed. Christopher Brickell; DK Publishing, 1996) indicates that Ranunculus ficaria (now known as Ficaria verna) spreads a foot or more, but the following information, from a local gardener (Paghat) who grows several cultivars of this plant, suggests that “more” may be quite a bit more. Excerpt: Due to their being potentially invasive, we placed them where it would not matter, but might even be rather nice, if they spread a great deal.
The species is considered invasive, as these sites indicate:
It is possible the cultivar is less invasive than the species, but I would certainly keep an eye on it.