Question
I have 3 miniature roses in pots sitting on my deck.  They get full sun about 8 - 9 hours a day.  They all have white mildew on their leaves.  My husband sprayed with a rose care product said to reduce mildew.  Nothing happened.  Can you tell me how to care for them.  Oh, I live in California in the San Francisco south bay area.

Answer
Mildew is a fungus so any fungicide should do the job for you. However there is another thing you could try. 1 tablespoon of baking soda in 1 quart of water sprayed on the leaves daily until they are clean should really help. If your roses are getting mildew then perhaps they are not getting enough air moving around them or even minis in a pot that is too small, will get mildew from roots that are too warm. All roses love cool roots. Mildew is usually caused by warm days and cool nights just like we get in the spring. Hope this helps.