some varieties are better than others at coping with shade, but if the area you've planted in gets half a day of sun, that should be fine, the time to worry is when a rose only gets an hour or two of sunlight., or possibly none at all.

It's a misleadingly described requirement - 'a sunny site'. What that means is three to four hours of direct sunlight a day, and even then plants will thrive if there's less, if the overhead light is good.