Published Oct. 9, 2016, Wyoming Tribune Eagle, “Fall color for next year’s perennial flowerbeds.”
Find fall color for next year’s perennial flowerbeds (full version)
Text and photos by Barb Gorges
In September, I had the opportunity to visit three public gardens: Chanticleer near Wayne, Pennsylvania; Berkshire Botanical Garden in Stockbridge, Massachusetts; and Yampa River Botanic Park in Steamboat Springs, Colorado.
What struck me was the colorful perennial flowers that were blooming in the fall. Of course, not everything that grows outside Philadelphia grows here in Cheyenne where we are two Plant Hardiness Zones colder, Zone 5.
We match the western Massachusetts mountains for zone, but they get four times our 15 inches of annual precipitation. Plus, they have acidic soils supporting those billowing mounds of hydrangeas I saw everywhere.
Even in Steamboat, only 700 feet higher in elevation, there are plants that require the protection of a thick layer of snow all winter which we don’t have.
So I decided to look around town, especially our own Cheyenne Botanic Gardens, to see what blooms late, for the benefit of bees and our own enjoyment.
Annual flowers are colorful right up to first frost, average date Sept. 20 (though in the last few years in some parts of town it may be as late as mid-October). But unless they self-seed, I can’t justify buying flats of annuals every spring to cover all my garden beds, nor have I the greenhouse to start my own. Instead I turn to perennials. Here are suggestions for you to add to your garden next spring. Or if we haven’t had a frost yet, find them on sale and plant them this fall.
I’ve done well with black-eyed Susan, Rudbeckia species. Their golden yellow petals and brown centers must have inspired the University of Wyoming’s selection of school colors. There are many varieties based on native species: short or tall, diminutive or gigantic flowers, mid-summer bloomers or later. Some bloom a long time—over a month. Some are better at coming back year after year.
My other success has been the fall-blooming asters, Symphyotrichum species. One variety is a 2-foot-tall shrub of lavender-colored, 1-inch flowers. It’s come back every year for over 20 years, waiting until mid-September to bloom. But another, brighter purple aster in a sunnier spot started blooming three weeks earlier and is still blooming well. Perhaps it is a newer variety bred for a longer bloom time than the native plants.
I hesitate to give you actual variety names because nurseries so often move onto the next best thing. You might as well go for what’s available rather than mourn what you can’t find. However, if you are interested in native perennials, check sources like www.alplains.com.
Blanket flower, Gaillardia species, is another hard-working perennial native to North America. It can start blooming in early summer. Horticulturists have had a field day designing varieties with different color patterns. A member of the aster family, it has petals that can be plain yellow, yellow with bands of red, or nearly all red-orange with a little yellow trim. Some are short, some tall. The seed heads are prickly little balls. If you deadhead them when they are finished blooming, they will put out more flowers. If you don’t, they will drop seeds that will sprout next year, like many other easy-to-grow perennials.
I’ve noticed that some of my summer bloomers will bloom into fall if I water them enough. I have a bed with a row of hollyhocks growing along the back. It gets watered by a sprinkler head that does a good job at one end but hardly gets water to the other end. Thus, the hollyhocks on the dry end finished blooming a month before the hollyhocks on the wet end.
Perennials that bloom in early summer may start blooming again in early fall—perhaps they don’t like hot mid-summer temperatures. I’ve had ‘Hot Pink’ Salvia, Salvia gregii, come back into bloom this year.
Microclimates make a big difference as to when perennials bloom. Nettie Eakes, assistant education director at the Cheyenne Botanic Gardens’ Paul Smith Children’s Village, said visitors are always telling her how the same flower in their yard is either behind or ahead.
The Children’s Village is lucky to be protected by high stone walls. On their north-facing sides, they provide shade and make a cool, slow-growing microclimate. On the south-facing sides, they absorb sunlight and make a warmer, faster-growing microclimate which can also extend the growing season.
The most noticeable perennial I found blooming September 18 at the Children’s Village was sneezeweed, Helenium autumnale, a 6-foot-tall plant with multiple small sunflower-type flowers, each with yellow petals and ball-shaped yellow centers. Nettie said they increase by sending out underground stems, but are not very invasive. Helenium comes in many other variations and bloom times.
Over by the office door, three-foot tall giant hummingbirds mint, Agastache pallida ‘barberi’, does not have shout-out-loud color. But it is a nice contrast: silvery spikes of tiny purple flowers. And maybe it will attract a late hummingbird—or hummingbird moth.
At the front entrance to the Children’s Village is ‘Karl Foerster’ feather reed grass, Calamagrostis acutiflora ‘Karl Foerster’. It’s a go-to plant for landscape designers these days, but that’s because it looks so neat. Growing around four feet tall, it starts out green in summer. Then the seed heads ripen to a golden wheat color. Finally, the whole plant turns gold. It is tough enough to stand and provide color all winter before getting cut back in spring.
A wispy, shrubby perennial also favored by landscape designers in our area is Russian sage, Perovskia atriplicifolia. Each branch sprouts from ground level, with silvery leaves on the lower half and small blueish lavender flowers on the upper half of each stem. It likes sunny spots and will spread.
Chatting with my Laramie County Master Gardener friends, Steve Scott and Kathy Shreve, I also have this list of fall bloomers for you to think about planting next year:
—Autumn crocus, Colchicum species. Corms are planted in July or August. The blossoms are much larger than spring crocus.
—Blue sage, Salvia azuria, native to central and eastern North America.
—Goldenrod, Solidago species, blooms are branches of tiny yellow flowers. Many are native to North America.
—Joe Pye weed, Eutrochium species, another North American native, sometime varieties are 5 feet tall, with panicles of purple-pink flowers.
—Maxmillian sunflower, Helianthus maximiliani, native to the Great Plains, 2 to 10 feet tall, branches with many yellow flowers.
— Purple coneflower, Echinacea purpurea, daisy-like, native to North America, many varieties, 1 to 4 feet tall.
—Snakeweed, Gutierrezia species, a shrub with yellow flowers native to western North America.
—Rabbitbrush, Ericameria nauseousus, or Chrysothamnus viscidiflorus. Both are yellow-flowered shrubs. The native varieties grow on our drier prairies.
—‘Autumn Joy’ sedum, Sedum telephium, is a stonecrop. The fleshy stems grow 1-2 feet tall, topped with bunches of tiny purple-pink blossoms. It can be found in the Cheyenne Botanic Gardens perennial bed.
— Obedient plant, Physostegia virginiana, looks like a 2 to 4-foot-tall snapdragon with pale lavender-pink flowers. It is also at the Gardens.