powdery leaves on my rosemary plant

I received a rosemary plant for Christmas and it seemed to be doing fine, but I just noticed that the leaves look like they have dust or powder all over them. What do I do? It is in an upstairs room with a southern exposure. It gets sun during the day.

The whitish powder on your rosemary leaves is powdery mildew. This specific fungus (unlike other fungus) thrives in a warm and dry environment. It attacks healthy rosemary. Once the plant is back outdoors, it should be fine.  Spraying the plant with a baking soda ( 3 tsp of baking soda to 1 gal water) mix should be a safe solution to the problem.  Several applications may be needed. Provide good air circulation around the plant. If you use your rosemary in cooking , a chemical treatment should not be used.

More info on growing rosemary: http://hortchat.com/info/rosemary-care