My favorite plants that flower non-stop until autumn frost are Angelonia and pentas. I haven't had any luck in wintering them over though. In my experience, these two flowers have never been bothered by any disease, bug or critter. Hummingbirds especially love the pentas, which by the way, has self-sowed in my garden, but late in summer, like the fibrous begonia I mentioned.
I could write another book on the subject, but ... well all right - one last remark -
Plectranthus argentatus - silvery, pebbled leaves with enormous candelabras of tiny ice-blue flowers at the end of summer. Usually they don't survive outside in z7 winter here, but when we have winter temps typical of z8, they winter over outside okay with no protection. One winter after bringing in some plants to overwinter indoors, I crushed a few plectranthus stalks that had gone to seed and sprinkled them over a pot in which another plant had not survived. How uncouth is that for sowing seeds? Anyhoo, tons of baby seedlings appeared and they all did well in the garden the next year - and note that this is a plant that does equally well in sun or shade - for me - and is highly drought tolerant.
Thanks everyone for an enjoyable thread - may your gardens all flourish.
karen
