Roses prefer a heavy clay loam, with a high amount of organic matter.  This makes it necessary for extensive soil renovation to accommodate their root systems which get quite large and deep with age.  The planting hole should be no less than 18 inches deep and wide and 24” is preferred as it cannot be redone once the rose has been planted.  Save 2/3rds of the original soil, breaking up clods to a finer grade.  Then add organic matter to the remainder of the fill and work well.  If the pH of the soil falls out of the preferred range of roses, which is between 6 to 7, it would be a good time to throw lime(If below 6) or sulfur(If above 7) to the soil as well.  Place some of the amended soil back into the hole, so that once it is firmed, the graft of the planted rose sits 1-2 inches below the finished grade.  The graft of the rose is located right where the main stem crooks out from a 90 degree angle from the rootstock.  Once the rose is properly situated, carefully cut the plastic pot from top to bottom, and then continue around the bottom until you reach the top of the other side.  Gently slide the two halves of the pot away from the rose.  This method allows the soil to stay intact which greatly decreases transplant shock.  Refill the rest of the planting hole with the amended soil, firming with your hands (not your feet) eliminating air pockets.  Water in well and you are done.  A 2-3” layer of mulch applied after planting will help conserve soil moisture, suppress weed growth as well as improve the appearance of the area.  It is neither necessary nor recommended to prune potted roses when you plant them.