Question
I have several minature roses bought at stores, then planted outside. Some are in pots, some are in the ground.
I live in Bakersfield, CA and lately the rose leaves have started turning yellow.

Answer
There are two distinct mini rose classes. Most are hardy little roses that do well outside with the same care as the big garden roses. But there is another one on the market which  is sold mainly for show and won't survive in the garden. To check and see what type of mini you have just look at the leaves if they are very soft to the touch and end to droop, then you have the ones that won't do well outside. If they are firm and don't bend easily, you have the regular ones. Your temperature is getting colder and most roses do benefit from a period of dormancy. I wouldn't worry if you have the normal minis just pull back on the watering and let them rest for a month or two. The other type you could try to save by bringing them inside and placing them on a south window sill. But even that may not please them and they will start dropping their leaves. Best to let them go dormant and place them in a garage until next spring when the weather warms up again and then replant outside. Hope this helps.