Hi Aniyan,

from another Port Orange, Florida resident!
When you water your roses, are you perhaps getting water on the petals? From my very limited experience, Roses prefer to be watered from the bottom; try to keep water from sitting on the buds, blooms and leaves.
Thrips are another possible suspect of brown petals; they feed on the petals. I only have three or four roses, all in containers and a week or so ago I found thrips on one of them and sprayed with an insecticidal soap which seems to have helped.
Hopefully some of our more expert rose growers will pop in with tips and suggestions since as I said, I am not real knowledgeable about roses.
Again, Welcome!