The Penstemon that doesn't quit
Dimensions: about 2'X2'
Blooms in warm weather
regular to moderate water (bottom to terrace zone)
Full to part sun
Hardy to about 0°F
It's hard to miss all the penstemons that are blooming in the spring. If you are like us, you are trying to collect them all, because you want to extend the season for as long as possible (different species bloom at different times, mostly in the spring). One species, however, has a giant growing season. Rock penstemon (Penstemon baccharifolius) can bloom from spring into fall. It will even cast out a flower or two during the winter if temperatures are spring-like.
Plants can take full sun to partial shade, but make sure they get enough sun to bloom. They are moderate water-users and require minimal care. Some people prefer to cut plants back to encourage a more bushy, compact look. We like ours wilder in our landscape. One thing to make sure of: plants should have good drainage. Rock penstemon does not like to sit in saturated soils.
Native from 2000 to 7000 feet of elevation on rocky slopes, limestone crevices and bluffs, and seemingly soilless cracks in limestone ledges. These habitats provide the required sharp drainage for rock penstemon in the Edwards Plateau and Trans-Pecos of Texas and south into Mexico.