You should dig a hole, in the same area, fill and I mean fill, with water and check how fast it drains.
Time it takes to drain will tell you what you have.
You should remove ALL surface weeds/grass from an area at least 16 inches in diameter from where the rose is planted, or you will be amending weeds.
I have heavy black gumbo, but it drains well and is very, very good soil, at that, I dig a hole much deeper than I plant IF I am putting a rose in an area where I have not before , OR, if I am putting a new rose in an old location.
I do not want old rose soil in the area I plant a new rose.
I generally use some bagged manure mixed with bagged top line garden soil mixed with native soil from my vegetable garden.
