Free rose photos online can be found at freepik, all-free-download.com and FREEBigPictures.com. These sites have rose photos that can be downloaded for free by anyone, as of 2015.
freepik has pictures of real roses, drawings and computer generated images. These feature a free license that allows users to download the images and use them as long as attribution is given. The images can be used for commercial and personal use with attribution. Attribution requirements and restrictions are listed clearly on the site under the "How to attribute?" link on the image's page.
all-free-download.com has mostly pictures of real roses, though drawings and CGI versions are also available in the search results. The results can be sorted by relevance, date and popularity to quickly find the best images. These images can be downloaded for free and used for commercial purposes. This site searches through multiple free image sites to find relevant pictures, so duplicates are possible.
FREEBigPictures.com has a small selection of rose pictures, but they are high resolution and good quality. They can be downloaded for free and used with attribution in a variety of ways that are listed on the site's "Terms and Conditions" page. Each picture has a form where users can submit comments about the image.