thanks, smilingcat. Two of the things I often do/did was to water at night and get the leaves wet...

I'll try the baking soda route, though I do believe it's too late for my plants. Even with no mildew I think it's getting too cool now. I shall remember for next year and fertilize it properly. They all started out so beautifully, it's such a shame to see them go downhill like that.