Many gardeners focus on tree planting in the fall. Now is a great time to shop for trees because you can catch a glimpse of what trees will look like in your landscape during the fall. Right now, our maples, tupelos, and witchhazel are starting to turn a beautiful array of colors. Planting in fall also helps reduce the risk of transplant shock or forgetting to water in the heat of summer.
Now is also a great time to shop for perennials.
Many associate flowering perennials with spring and summer but there is a surprising amount that flower in fall. By adding fall flowering perennials, you can extend the floral interest of your landscape by at least 2 months. Perennials that flower this time of year are also critical to pollinators before they prepare to lay eggs and hibernate.
I think some people view fall as a season of decline (with trees beginning to lose their leaves and all) but they should realize that fall is peak season for many garden plants.
Many summer flowering perennials are still showing color in early fall such as Black Eyed-Susan (Rudbeckia spp.) and Coreopsis (Coreopsis spp.). These transitory perennials are important as they bridge the two seasons. That said, I want to share with you my favorites that are strictly fall flowering perennials.
One of the most ecologically important plants east of the Rockies, goldenrod should be utilized more by more gardeners and landscapers alike. Goldenrod is adaptable, long-lived, and remarkably deer resistant. It flowers for a lengthy period and attracts a diverse number of pollinators. It’s also beautiful!
Two hold-ups for why this perennial isn’t popular in the garden is that many consider it a “weed” and think it causes allergies. I define a weed as a plant that doesn’t belong. Since goldenrod is a native flower to Pennsylvania, I’d say it absolutely belongs. With that said, the species most people are familiar with is Canada goldenrod (Solidago canadensis) which is the most aggressive species. We carry other species of Goldenrod that are more behaved in the garden.
Contrary to common belief, goldenrod is not responsible for fall allergies. Goldenrod pollen is heavy and sticky and requires pollinators to move it around. Ragweed (Ambrosia spp.) and other wind pollinated plants, which flower at the same time, are the true culprits of fall allergies. Wind pollinated plants create enormous amounts of pollen as they rely on mere chance, rather than pollinators, to reproduce.
I like the cultivar “Solar Cascade” (Solidago shortii ‘Solar Cascade’) which has a graceful arching habit. It looks best when planted along rock walls or in mass plantings. I grow “Fireworks” (Solidago rugosa ‘Fireworks) in my garden which has a strongly upright habit and cascading flower stems. “Little Lemon” (Solidago ‘Dansolitlem’) is a dwarf hybrid, perfect for small spaces or in groupings at the front of a garden bed.
Asters are quintessential to any landscape that tries to have fall appeal. Asters come in hues of purple, pink, and white. When planted with goldenrod, the complimentary colors give a “pop” of contrast which quickly draws the eye. Most cultivars available are hybrids of New York aster, New England aster, and Aromatic aster, including the “Woods” series and the cultivars “October Skies” and “Purple Dome.” I grow Bluebird (Symphyotrichum laevis ‘Bluebird’) and Woods Pink (Symphyotrichum ‘Woods Pink) in my garden.
Like goldenrod, asters are durable, native garden plants that provide necessary food for pollinators late in the season. Most species flower September through October.
Though it blooms in late summer, I should give credit to the wood aster (Symphyotrichum divaricatus), which has dainty white flower and is a great choice for the shade garden. I grow this beauty in one of my shade beds.
This perennial has flowers that resemble the appearance of an aster which is why it’s alternatively called False Aster or Thousand Flowering Aster. Boltonia is a larger perennial, growing 4 to 5 feet tall, so its best suited in the back of a garden bed. We usually carry the straight species and the cultivar “Snowbank”, the latter which is somewhat more compact. Like other tall perennials, you can cut Boltonia in half in early to mid-summer for a shorter, fuller habit. Boltonia flowers from August to September though a summer chop will delay the flowering by a couple weeks.
Boltonia is very adaptable but keep in mind that too much moisture may cause flopping and too dry may result in less vigorous flowering. Site it in a good spot and it will reward you with fall flowers for years to come.
Like goldenrod, perennial sunflowers bring vibrant hues of yellow to the fall landscape. Sunflowers amidst showy ornamental grasses and trees in fall color is a sight to behold. There are many species but most of them flowering from August through October, with Willowleaf sunflower (H. salicifolius) flowering well into November.
I wish people didn’t call native perennials “weeds” but here we have it. This is another fall flowering plant that’s tough (hence the name) and unpalatable to deer. Ironweed has small purple flowers that I think resemble little paintbrushes. There are several species in cultivation, such as New York Ironweed (the most common) and Tall Ironwee, but my favorite is a selection of Letterman Ironweed called “Iron Butterfly” (V. lettermanii ‘Iron Butterfly’) which I grow in my garden. This perennial grows knee high with a lacy, upright habit, and sports hundreds of small purple flowers in September.
I consider “Iron Butterfly” to be a foliage plant as well as a flowering plant. The foliage also resists flopping during the winter which adds texture and interest (so don’t trim them back in the fall!)
This species of monkshood flowers late, usually from August to October, sometimes November. Unique azure flowers bloom atop tall stems with interesting foliage underneath. Azure monkshood does best in part sun.
Stonecrop is a popular succulent plant that is a great choice for hot, dry areas. It grows well in shallow, rocky or clay soil. Be aware if the soil is too rich or moist, it will flop. This sedum has attractive foliage and great flower power in fall. The most popular cultivar is “Autumn Joy” but we carry many others.
Toadlily is an excellent perennial for the shade garden, and as a native of east Asia, fits perfectly in a Japanese or Zen Garden. This 1-3 foot tall plant boasts attractive foliage and unique flowers in early fall.
If you read my last post, you’d remember that the “feathery” ornamental structures on grasses are their flowers (and subsequently, the seedheads). Most ornamental grasses flower in early fall. Any landscape that cares about fall aesthetics should also be utilizing ornamental grasses. You can read my last post here: https://www.plumlinenursery.com/2020/09/22/kicking-grass-and-taking-names/
While other nurseries offer limited selections this time of year, we maintain a reasonably extensive selection up until mid-November when we officially wrap up for the year – including perennials. Come on in and see what’s flowering and get them planted while the ground is still warm. Happy planting!