Cold hardy vegetables such as leeks, Brussels sprouts, arugula, and
carrots can withstand some frost. Annual flowers such as snapdragons and
violas can too. But what about those plants that you want to keep
growing in spite of the cold?
Late summer is known for tons of tomatoes, asters and goldenrod in
bloom, and white patches on lilac, birch, phlox, bee balm, squash and
other leaves. It all sounds ideal, except for those white patches. They
are the sign of powdery mildew disease.