@A_dinosaur ....
Spider mites prefer a HOT, dry climate to flourish. For me, they are easily controlled by washing the plants throughly with water ... especially the undersides of the leaves .... with just water for three days in a row. This breaks the breeding cycle. After that, you only need to wash your plants down once a week.
I have followed this practice for years and grow over 100 roses and have always been successful in controlling spider mites in my garden;
I have one rose that I call the canary-in-the-mine. It always gets spider mites first. As soon as I see it start to get spider mite damage, I go into action and wash down all of the roses to break the breeding cycle. I have never used any chemicals to control a mite infestation.
Of course, there are a lot of right ways to grow roses ...