Gentianopsis crinita
Fringed gentian
 
The blooms of Gentianopsis crinita are deep blue and appear in late summer to fall, usually around August or September. They open in the cooler days and close in the heat. Fringed gentian does well in moist soils, and it prefers full sun. It's a great choice for a spot with consistent moisture, but make sure it’s not in standing water – it doesn’t like wet feet for too long.
 
Its flowers attract various pollinators, including bumblebees like Bombus impatiens, who visit for nectar. It also tends to be deer-resistant, so you won't have to worry about your garden visitors munching on it.
 
Photo credit to: Doug McGrady