not really any facts to opine on . if plants dont flower.. its usually too much of the wrong fert ... or not enough sunshine... are hers potted and indoors?? ken

I've never had issues with Dianthus coming back other than the voles eating them, and even then some sprigs usually survive. I've planted in the fall without issues and I am north of you, I think. Gaura is hit or miss regardless. It wants well-drained soil, and will die in cold winters, especially if there isn't good snow cover, but might survive in milder, dry winters.

The first frost usually isn't for at least another couple of weeks to a month. (mid-late October) Yes, they die back to the ground, but I leave the dead stems as they are, over the winter and prune them back in the spring when I start seeing new growth at the base of the plant. Yes, I am positive they are aphids. I've even noticed a lady bug or two feasting on them. (just not nearly enough ladies to make a difference) No, I've not had a problem with bugs in previous years. Not every year, but I do remember planting Petunia's around them at least once or twice - not knowing they are aphid-deterrent plants - so perhaps I need to do that for next year? The only thing different this year is that I added 8 new Gaura bushes to my existing 3. I'm not so much worried about my established bushes, just the newbies.

Babs I have Gaura 'Summer Emotions'. It was touted to be hardier than all others. I put in 6 and strangely the one that is still going years later is in an area that developed a drainage issue and is almost soggy. The others were in a well drained position but had Juglans cinerea - Butternut trees in relatively close proximity. Some plants cannot survive the juglone at all. I blamed it for their demise.