Our Native Penstemons

By Bobbie Stephenson, President CNPS-SD in San Diego Horticultural Society-Let's Talk Plants!

Penstemon centranthifolius

During these hot summer days, you might want to spend some time thinking about the native species you would like to plant this fall. Fall is the perfect time to plant natives so they can take advantage of the winter rains that we receive in our Mediterranean climate. Some of the showiest natives are the penstemons, of which we have several native species in our area.

Formerly placed in the figwort family (Scrophulariaceae), new genetic research has led to the reassignment of Penstemon and other closely related genera in the vastly expanded plantain family (Plantaginaceae), which includes many showy genera, such as Antirrhinum, or snapdragon (yes, we have native snapdragons!) and Digitalis (including Digitalis purpurea, the non-native foxglove), as well as other genera that are not showy at all. The plantain family is named for the genus Plantago that consists of small, inconspicuous plants, commonly called plantains or fleaworts, that bear stalks with cream colored, almost translucent, flowers. Note that these are not to be confused with the unrelated, edible plantains.

Penstemon spectabilis

One of our most popular native penstemons in horticulture is the showy penstemon (Penstemon spectabilis), a perennial that grows naturally inland from about Poway and Lakeside to the foothills on the coastal side of the mountains, and up onto the slopes of Palomar Mountain. Showy penstemon, seen at left with its clusters of purplish, almost two-toned flowers, generally reaches three to four feet high and can be a focal plant in the garden or a tall background specimen for a colorful border against a wall or fence. It is generally easy to grow if planted in the sun and not overwatered.

A lower growing but no less stunning species is foothill penstemon (Penstemon heterophyllus). It’s a long-lived perennial about a foot high with flowers in bloom April through August that are similar to those of showy penstemon, but borne singly in the axils of its leaves. It prefers to be planted on slopes and takes minimal care and maintenance. Again, don’t overwater it.

If you are interested in red flowers, try scarlet bugler (Penstemon centranthifolius). With its bright red tube-shaped flowers that bloom from April through July, this species draws in the hummingbirds, its primary pollinators. Scarlet bugler likes dry slopes and lots of sun, and naturally grows from Baja California through the foothills and mountains of San Diego County northward into the southern Sierra Nevadas at elevations of up to 6,500 feet. They couldn’t be missed along the Sunrise Highway when I drove up to Laguna Mountain in July.

Drought tolerant and easy to care for, native penstemons provide a big splash of color in the garden.