|Is there any kind of weed spray that I can use around rosemary plants?|
I don't think you'll find any with a label allowing such use. Weed control really depends on the type of weeds. If they weeds you are seeing are primarily grassy weeds there are products containing fluazifop and sethoxydim which kill grass but not broadleaf plants, of which rosemary is one. But you will need to check labels to see if rosemary or herbs in general are on the label.
Many weeds can be prevented by use of a mulch. I like to lay newspaper 4-6 sheets thick, wet it and then cover it with leaves or other organic materials. This keeps weed seeds from growing in the area for several months.
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