It has been a dry spring and summer on Cape Cod. This is good news for roses because it means less black spot, but bad for garden Phlox because it means more powdery mildew. This fungal disease is always worse in dry weather because when there are periodic downpours the spores get washed off the leaves, so it’s not as quick to establish. This year that fine, white-gray powder hit my Phlox early and hard.
I don’t bother spraying in an attempt to control powdery mildew. (And by the way…that rumor that spraying with milk will control the problem? Just a rumor and it doesn’t work.) If the Phlox is flowering well despite the problem I just try to see it as a silver-foliaged plant. A flowering Artemisia, if you will. But at a certain point, if the mildew covers the flowers as well as the foliage, the plant starts to lag and become unattractive.
The question I use for judging how things are doing in my garden is this: “What is this bringing to the party?” If the answer is “Not much!” the plant has to go. As soon as I get some fill-in annuals to place around these phlox they will get cut to the ground. They’ll be back next year, and perhaps we’ll have the perfect combination of periodic rain, and dry periods, that will keep the plants mildew free. Perhaps. In the meantime, I’m saying, “Thanks for coming. Goodbye!”
Plant annuals in August? Why not! Here on Cape Cod the annuals that I put in the garden now will flower well into October. I’ll get almost three months of pleasure from them, so it’s well worth doing.
Even if you live where a first frost arrives in September, look at it this way: for the same cost as going out for a nice dinner you can have flowers that last for many days instead of a meal that only lasts for a couple of hours.