What household products can be used to spray/treat/prevent powdery mold on Petunias?
Powder Mold on PETUNIAS
Certified GKH Gardening Expert
There isn't really a "household" product that will be effective, but you can use neem oil, in addition to correcting whatever is causing the powdery mildew. This article will give you some additional information: https://www.gardeningknowhow.com/ornamental/flowers/petunia/problems-with-petunias.htm