Documents: Regional Gardens (Canada) - Prairie:

Fall Wildflowers Create Interest
by Nancy Pollard
October 5, 2014

Some of the best garden perennials for fall are also good at supporting our native wildlife.

“Native wildflowers and their cultivars—yellow goldenrod, purple asters, golden sunflowers, and dusty rose Joe Pye—create a lot of interest not only because of the attractive flowers but also for the amazing variety of native butterflies, moths, and other insects that feed on them,” said Nancy Pollard.

“Fall wildflowers are particularly outstanding at attracting adult moths and butterflies, which lay eggs that hatch into larva (caterpillars). The larvae provide a high-protein source of food for many birds, particularly warblers and neo-tropical migrant birds of conservation concern. Birds are very good at keeping populations of these insects in check so it is a very good situation for all,” Pollard explained.

Flowers that bloom in the fall can to be tall, up to 2 to 6 feet or more depending on the species and cultivar. Pollard said these often work best at the back of the flower border.

“Some varieties have been selected and given cultivar names because they are shorter, more compact or more disease resistant than the average species plant. Cultivars are usually propagated by cuttings. Because cultivars do not always come true from seed, you may want to cut back stems after flowering to prevent self-seeding of cultivars,” she said.

Goldenrod (Solidago sp.) thrives in sun to part sun and is a deer-resistant perennial. Pollard described the flowers as “stunning” when paired with blue and purple New England asters. Many species are available. Great performers include:

• Solidago flexicaulis 'Variegata': with variegated foliage it brightens semi-shaded wooded areas. This goldenrod is over 4 feet tall and has a spreading nature. It blooms from early September to mid-October.

• Solidago rugosa ‘Fireworks’ has graceful fine textured foliage with arching branches. The stems of the golden blooms arch in many directions like fireworks. It grows three to 4 feet tall. It tolerates wet soil and grows slowly by underground rhizomes but generally doesn’t get out of hand. It blooms mid-September to late October.

• Solidago sphacelata ‘Golden Fleece,’ which has pyramidal densely flowering stems that form a compact groundcover, grows to 18 to 36 inches depending on site conditions. It is drought tolerant and is also good for fall container gardens. September flowers attract hummingbirds, bees, and butterflies.

Asters (now in the genus Symphyotrichum but widely sold as Aster) do well in sunny sites with good air circulation or their foliage might suffer from mildew. “Pinch back the taller varieties until June as you would chrysanthemums. Most will tolerate sandy, clay, poor soils and some drought. There are mixed reviews whether these are deer resistant or not, leaning toward not. It depends on many factors,” Pollard said.

Two favorite asters trialed at the Chicago Botanic Gardens are New England aster, A. novae-angliae 'Alma Potschke', a 3-foot, showy reddish pink and 'Purple Dome,’ a dwarf (18 inches) purple.

Aromatic aster (Symphyotrichum oblongifolium, formerly Aster oblongifolius) was also a Chicago Botanic Garden favorite. Abundant sky-blue flowers are borne on stiff, 1- to 3-foot stems into October or later before frost. The cultivar 'October Skies' is a winner at just 18 inches high.

Pollard said aromatic aster 'Fannys’ is also a good cultivar with abundant 1.5-inch, dark purple and yellow flowers. This blooms very late in October or even November. The gray-green, rust-resistant, fragrant leaves spread to form large clumps 3 to 4 feet tall. “It grows easily and quickly in dry to average conditions and tolerates clay or sandy soil,” she said.

Joe Pye (Eutrochium, formerly Eupatorium) is a great plant not favored by deer. The showy 'Gateway' has burgundy stems 4 to 6 feet tall, topped by dusky rose nosegays that are 1 foot across. “Cut back the tips in June to create a bushier plant. It is a magnet for butterflies and birds in the fall,” she added. Joe Pye prefers full sun and likes average to abundant water.

Pollard said that while there are some perennial sunflowers (Helianthus sp.) available commercially, helianthus annuus, the native annual, is so beloved, it is a garden staple. “There is a sunflower for every garden situation ranging from the 16-inch Elf to the 3-foot Solar Flash, to the 12-foot Mammoth. The color palette has expanded from the always alluring Van Gogh painting’s yellow with a brown center, to whites, burgundies, and rose pink, with many tints and shades of colors in between,” she said.

“While they are easy to grow from seed, sunflowers prefer sun,” Pollard noted.

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