A rose variety may be patented just like any other plant. A patent grants to the holder exclusive rights to distribute and propagate that variety of rose. Of course the patent holder can license others to distribute and propagate that rose. A patent lasts for 17 years, so most older roses aren’t currently under patent. After the patent has expired, anyone can distribute and propagate that particular variety.
Some nurseries divide their roses into patented roses and non‑patented roses, with the patented roses costing more. This is because they may freely propagate the non‑patented varieties, but their is usually a fee for propagating patented varieties.
It is illegal to asexually reproduce a patented plant, even for personal use. It is, however, legal to use a patented rose in hybridizing.