These Erigeron, Erigeron karvinskianus are ideal for growing in cracks in paving or crevices at the base of walls. They spread their seed and look delightful for most of the summer. The outer petals start off by being white and gradually change to pink over time. I started off with one plant and now they have spread along the base of the walls around the house and at the base of this raised bed in the front garden. I have tried collecting seed but they seem to do best dispersing it themselves. It is also known as Mexican fleabane and first appeared in this country in the nineteenth century. Apparently the name comes from the fact that these plants and other daisy like plants were said to have insecticidal properties.