My Carpet Roses of 3 years have very small blooms?

I have had my carpet roses for 3 years and I noticed that the blooms are not opening. They look as though the cold got to them even though it is spring. I read that humidity will cause small blooms. I have searched the website for answers. I also read that thrips may be the reason. I also recently put down weed block and covered it with peat moss. Any help would be appreciated.My Carpet Roses of 3 years have very small blooms?
Do you feed them regularly? I like Scott's Rose Food - it's EXCELLENT! Also, banana peels are great for roses. Just place them around the roses, under mulch if you'd like. I've never had carpet roses, but I have other types. =)