Julie, I had this with planting new ferns and cytisus plants - replanted three times, then washed the roots thoroughly and replanted and they were not touched. All the explanation I could come up with was that the nursery had used Fish, blood and bone meal as fertiliser!! It was only because I had loads of plants to put in that I had not washed the roots, as I try to keep imported vine weevil out of my garden. So perhaps you could wash the roots of your roses. As for the crocuses, plant them quite deep as they will find their own way up if need be, but it could be squirrels.