This is a picture of the daisy steps- or daisyless steps!
Every year we find that the Erigeron karvinskianus struggles to establish at the top of the daisy steps. No matter how many we carefully plant up thay always look thinner at the top than the bottom.
And here's why......
some kind of animal- possible badger as there are sets nearby, or possibly squirrel- are digging them up. They are not interested in eating the plant but whatever is buried behind it. That's why I think it must be the badgers listening out for bugs and grubs moving in the soil and then digging them out.
Just part of a series of constant battles with nature!