Some 15 years ago I had a neighbour with a big aviary (and lots of birds in it) in his backyard. Behind the fence of our properties it was forest. Once a week he cleaned the aviary and threw the sand and the fallen (and not eaten) birdseeds over the fence. Don't know exactly how lang after that but the most beautiful flowers (some I had never seen before) started growing there. Let nature do it's job I would say.