This thread is the reason forums are so very helpful. I started gardening around the time when every magazine had "The English Border" garden on their covers. The advice regarding cold tolerance was spot on. When the perennials popped out of my spring soils, it was exactly as promised. Vibrant lovely plants left me feeling like a real gardener, not the novice I was. August temps, however brought me back down to earth, as I was staking and watering and removing plants that were ready for fall to come back, right when I had about 3 weeks of hot sun left for them to endure.
I will be thinking of this very good question every time I am considering a new plant for the yard.
