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Index : Flowers - Perennials
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- 5. Penstemons - Spring Color for Desert Landscapes - Top
- One of the best groups of flowering perennials for desert landscapes are the spring flowering Penstemons. Penstemons are native throughout North America. Although the number of Penstemon species is greatest for temperate climates, there are several excellent species that flourish in dry climates, and are in fact native to the desert southwest.
As a group, the desert Penstemons have showy flower spikes arising from rosettes of attractive gray-green to blue-green leaves that grow in a mounding fashion 12 to 30 inches tall. Flower spikes shoot up 2 to 3 feet above the leafy base and are lined with showy tubular flowers in bright colors from red to rose pink to purple depending on the species. The blossoms are a great attractant for hummingbirds.
Desert Penstemons are hardy and adapted to Arizona low, middle and high elevations. As you expect, there very drought tolerant and do not require fertilization. They grow easily from seed, and once established, reseed readily on their own. The first year’s growth is vegetative. Come the following spring, flowering begins. Plants remain viable and continue to bloom for several years.
Penstemons require full sun or light-filtered shade. Plants grown in full shade will thin and sparsely flowered. Although they grow just fine in their native desert soils, penstemon do respond to the incorporation of organic matter into the soil with thicker vegetative growth and more bloom spikes. Water requirements vary somewhat between species, but in general they’re quite happy with applications of water twice monthly during hot weather. However, to establish young plants water twice weekly during the first few weeks after planting to develop a strong root system.
Parry’s Penstemon (Penstemon parryi) (Penstemon parryi) is a favorite because of it’s numerous bright pink flowering spikes, a color not often seen among desert bloomers. Flowering begins in early March and continues for several weeks. Leaves are a silvery green and oblong to lance-shaped. Plants vary in overall height from 2 to 4 feet.
Scarlet Penstemon (Penstemon barbatus) (Penstemon barbatus) is a large Penstemon growing up to 5 feet tall and three feet wide. It has bright red blossoms which appear in late spring in the low desert to early summer at higher elevations.
Firecracker Penstemon (Penstemon eatonii) (Penstemon eatonii) as the name implies has bright scarlet-red flower spikes rising above attractive green to blue-green foliage. Plant grow to an overall height from 2 to 4 feet. Flowering occurs in late winter and early spring. As with other Penstemons, eatonii benefits from organic matter in the form of compost, chipped or ground bark as a mulch placed over the soil to conserve moisture and keep roots cool.
Superb Penstemon (Penstemon superbus) (Penstemon superbus) blooms beginning in mid-spring to early summer with flowers ranging in color from corral-red to scarlet-red. Leaves are dark green to blue-green in color. Usually 2 to 3 feet high, with extra watering superbus can stretch up to 5 feet, making it ideal for backgrounds to lower growing desert shrubs. In windy areas, the tall flower spikes of superbus may need staking to hold them upright.
Finally, Penstemons benefit from grooming to remove flower spikes after bloom. However, if you desire plants to reseed themselves, wait until seed has formed and dropped before pruning off the spent flower spikes.
“Making New Plants from Cuttings & Layerings” will be the topic for this week’s garden demonstrations. They will be presented on Wednesday at 9 a.m. at the University of Arizona - Pima County Extension Center, 4210 N. Campbell Ave (central); and at 1 p.m. at the Wilmot Library, 530 N. Wilmot Road (east), and on Friday at 1 p.m. at the Oro Valley Library, 1305 W. Naranja Drive (northwest).
Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona,
520-626-5161. - Updated: March 29, 2006
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