Rocky Mountain Penstemon - Penstemon strictus
This electric blue Penstemon looks like it glows in the dark. The tall showy spikes are visible a quarter mile away, and they last for over a month.
Native to the southern Rockies, this electric blue wildflower thrives in most of the western U.S. At home in zones 4-9, it loves fun sun, needs minimal water, and is one of the longest lived, most easily grown Penstemons.
Your plants will grow to 24' x 36" wide, and spread via stolons to form large clumps, though they're not invasive. Sow the seeds in fall (or stratify), then sow them just below the soil surface. They'll come up on their own every spring.