The Mexican Blue Penstemon, Penstemon amphorellae, is a Mexico native, and hardy in the Tucson and Green Valley areas to well below freezing.
This tough perennial has lovely soft blue flowers, quite a change from the many penstemons you might be familiar with on the pink, red or orange side. It is fast growing, reaching under 2 feet tall and about a foot wide. The leaves are narrow and light green. As with all penstemons, this plant attracts hummingbirds because of the tubular flowers.
As a native to Mexico, the Mexican Blue Penstemon prefers light shade in the hot desert. Planting under a native tree such as the velvet mesquite is ideal. At least provide afternoon shade to protect it from our scorching west sun.
The Mexican Blue Penstemon needs additionally moisture other than rainfall to perform well. If conditions are right, it may reseed itself throughout your yard.
Reference: Mountain States Wholesale Nursery and Gregg Starr Nursery Plant Info Sheet, 1999.