Last year I happily planted nine roses. They lined the back of my garage on the patio and bloomed very well. It was beautiful! This year there are no roses. It appears they are all dead. I have been watering them anyway just in case but with no sign of life. Obviously I did something wrong. I used potting soil mixed with peat and soil improver of some kind. They get about 6 hours of sun each day. I saw no disease on them or in them. What did I do wrong?!!!!