I have had crocus in my front garden for many years. In the last two or three years I have found them popping up in the field which is the far side of the stream which runs next to our house. Our field is not treated with fertilizes or chemicals. They have also appeared behind our two beehives which are behind our house. (There may have been some crocus planted behind the house at some stage but not there.) Every year there are more bright orange crocus in the field. I have heard of a similar situation with Iris Reticulata. Could you please tell me how these crocus are spreading?