This may be a pain now, but it will be worse later if you don't take care of it before you plant your roses. Second, get your soil pH tested. It should be around 6.5 or so. Be sure to follow the directions on the lime and sulfur packages. This applies to any type of soil.
Organic matter is essential for making healthy soil, which results in well fed and healthy plants.
Compost is one of the best sources of organic matter. Organic matter loosens up the soil, improves aeration and drainage, and provides food for all living organisms in the soil. Fourth, if you have clay soil, add some gypsum, sand and organic matter to help loosen it up. If you have sandy soil, just plan on adding more organic matter or even some black topsoil to increase its water-hold capacity and fertility. Phosphorus that is in the soil doesn't move much, so it needs to be placed where the plant can use it.