I upended most of my ailing plants on the balcony. And found that their demise has mostly been my error. I recall now, I had read somewhere advice to put a layer of shredded leaves at the bottom of outdoor containers, to retain moisture in the heat. And thinking of our hot summers, I did just that. It retained moisture too well. Even with the bottommost layer of crocking in place, the lower two or three inches of every pot were completely waterlogged. These are pots that were dry on the surface, and drain pretty well out the base when I do water them. So I scraped off the layer of compacted leaves, inwardly cursing my folly, and repotted them into drier soil with extra crocking just in case. Some had their root system half-rotted away. Not sure if they will recover. Even my Mints failed. Yeah, they like dampness. No, they do not live in a bog.
Plants this applies to were: Mint, miniature Rose, Dogwood sapling, Tithonia (which still hasn't flowered yet), sprawling Marigold (also not flowering) and a pot of Mums.
I also found that my Echinacea suddenly had a lot of leaves limp and blackened. Plucked a few off and found a mass of tiny dark caterpillars under the curl of one leaf. Errrgh. My older daughter was delighted at the caterpillars and didn't want me to throw them out, I was upset at the devastation they have already caused and how quickly they could eat through my entire little garden if left in place.