The long, blistering-hot dry period we just went through proved the garden value of a pretty, hardy succulent from the American mid-west. Rock Pink (Talinum calycinum) is a member of a genus which includes some summer-rain-intolerant species from the Rockies, collectively called Fame Flowers.
We are growing Rock Pink for the first time this year. It produces lovely vivid purple pink flowers on long wiry stalks, above the succulent green foliage. The flowers do not open until noon, last only one day, but are continuously replaced by new blooms.
Rock Pink’s home range is Texas to Illinois. William Cullina of the New England Wildflower Society, who is usually a pretty reliable authority, says the plant is hardy in Zone 4 if given excellent winter drainage. A south-facing rock garden would be an ideal home for this plant, in the north. We have recently planted several in groups of five and seven or more in our newly expanded rock garden. With the flowers a bit on the wispy side, they seem to call out for planting in groups. We need some vivid colour and we can certainly use a plant which loves heat in our summer garden. It is visited by bees. 
Beaux Arbres has this plant for sale in the nursery, if you would like to give it a try. I cannot absolutely guarantee it will be winter-hardy but it is both charming and easy to raise from seed. It might even spread a bit by volunteer seedlings.
Beaux Arbres Plantes Indigènes / Native Plants 