Family Plantaginaceae, Genus Penstemon
3-9, although some varieties may only be hardy to zones 4 or 5
Most penstemons are one to three feet tall, but the Palmer’s penstemon can grow up to six feet.
Early to midsummer
Penstemons are easy to start from seed, which is just as well, as many of the species are short-lived perennials. Seeds may germinate better after a period of aging, mimicking their conditions in the wild, so you can store seed for several years before planting. If you sow the seeds in the garden, do so in autumn, to allow a natural stratification period. Alternatively, you can stratify the seeds in the refrigerator for three months if you plan to start them indoors. If you purchase penstemon seeds, be sure to check the growing zone, as tender varieties like the ‘Tubular Bells’ series are often sold alongside the hardy perennial types.
Penstemons don’t compete well with other plants, so give them plenty of space in the garden. Plant penstemons in the spring, and choose a site with full sun and very well draining soil. These plants are prairie natives, and prefer rocky or sandy lean soil types over rich garden loam. It’s OK to amend the soil with compost to achieve proper tilth, but avoid manure applications.
- Penstemon plants look best in groups of at least three to five plants.
- Include the smaller varieties of penstemon in the rock garden.
- Penstemon flowers are a valuable source of nectar for bees, butterflies, and hummingbirds in the wildflower garden.
- Plant tall penstemon types in the middle or back of the sunny mixed perennial border.
- Penstemon flowers make good cut flowers, although most people don’t think them as bouquet candidates.
- Browsing deer avoid penstemon plants.
- Dark Towers: Similar to Husker Red, but with pale pink flowers and darker foliage.
- Elfin Pink: Topping out just shy of 12 inches, a good rock garden plant.
- Husker Red: Perhaps the most well known variety, due to being named perennial plant of the year in 1996. Plants feature reddish-purple foliage and white flowers.
- Jingle Bells: Reddish orange flowers are a beacon to hummingbirds.
- Piña Colada series: Blue, rose, or white flowers on compact plants.
- Red Riding Hood: Monrovia’s successful introduction has red flowers and an upright growth habit.