If you can believe it, fall arrives this month! Much of the country is still wading through the dog days of summer, while others have their first snow. Days are growing shorter, with the slightest hint of changing sunlight, leaf shades, and those blue-sky fall days. Fortunately, there’s plenty of time for fall seed sowing.
Such variable conditions in September make sowing perennial seeds highly specific to your growing zone, climate, and first frost date. There are numerous seeds to sow for cool climates this month as fall rounds the corner. In areas still contending with heat, wait until temperatures mellow to sow. The aim with a fall sowing is for seeds to overwinter. Many perennial seeds require a chill period (cold stratification) to develop, which means September-sowing is ideal. They’ll germinate in spring as temperatures warm.
To sow in fall, rely on plants that naturally drop seeds this time of year. Hardy perennials, including natives, bear seeds well-suited to overwintering outdoors. We also have a few selections to get going now in mild climates before the first frost. Get a jump start with easy fall sowing, and delight in seeing what pops up come spring.
California Poppy
California poppies have feathery blue-green foliage and cupped orange blooms. Tough as nails, they grow in challenging situations, including poor soils and along slopes.
The bright blooms emerge on stems above foliage in late spring to early summer. A cool-season annual or short-lived perennial, they pop up in California in the winter in mild microclimates.
Showy in a naturalized planting, nothing beats a stunning poppy super bloom when they emerge en masse. Scatter plenty of seeds for a mini version in your garden. Sow poppies in early to mid-fall for a spring flower. Mild climates benefit from late summer and early fall sowing for winter and spring blooming.
Joe Pye Weed
Joe Pye weed lends a wild, naturalized look to the border, though the plants aren’t actually weeds or aggressive spreaders. The tall natives grow in tough situations like roadside ditches, but they’re outstanding with clouds of domed flower clusters. Dwarf cultivars make them easy to fit into various garden spaces.
In summer and fall, the purple-pink flowers attract beneficial insects. Coarse, long leaves are dark green with purple-hued leaf nodes. Seed pods last into winter and extend the interest.
Joe Pye weed thrives in rich, moist, well-drained soil conditions but tolerates poor soils, too, including clay. Plant perennial Joe Pye weed seeds in September for a beautiful show next season.
Foxglove
Foxgloves are cold-hardy biennials that bloom in spring and summer in cool climates. They put on a showy spring display in warm climates until temperatures rise. In areas with hot summers, treat them as annuals.
Foxgloves produce lines of bell flowers on tall, sturdy stems. Blossoms in purple, rose, peach, and creamy white often have freckled throats.
In mild climates, surface-sow Digitalis seeds in the late summer and early fall after temperatures have cooled slightly. Without burying, lightly rake the area to nestle in seeds so they don’t drift or wash. Foxgloves grow best in consistently moist, organically rich soils with good drainage.
Black-Eyed Susan
Black-eyed Susan is a native prairie wildflower that blooms continuously from summer through frost. The golden ray flowers have chocolate centers. They rise prolifically on slender stems above dark green basal leaves.
Black-eyed Susans are adaptable plants that thrive in heat, humidity, and drought. These easy-care perennials make the most impact planted in groups. They divide easily to share them among garden locations.
To direct seed rudbeckia, scatter seeds and lightly tamp them into place. Seeds need sunlight to germinate and don’t require much cover.
Prairie Coneflower
Prairie coneflowers are long-blooming and have red, yellow, or dark purple-red flowers. The unique ray petals droop below a central gold-brown disc—a bit like a badminton shuttlecock.
Flowers rise on tall stems and reach one to three feet tall. Pollinators and songbirds enjoy the nectar, pollen, and seeds as a food source.
Prairie coneflower is fast-growing, drought-tolerant, and withstands competition from other plants. It grows aggressively in optimum growing conditions and may overtake weaker growers.
Columbine
Columbine is a graceful native wildflower with delicate blooms and attractive compound leaves. Depending on the variety, the nodding flowers range from vibrant red and yellow to rich blues, purples, and pinks.
Columbine occurs naturally in cold climates and benefits from a cold period of 30 days (or more) to germinate. Scatter seeds on the soil surface and cover lightly with soil to keep them in place.
With a habitat along woodland edges, clearings, and riverbanks, columbine grows best in moderately moist, well-drained soils. Foliage is semi-evergreen unless temperatures become too cold or too hot, where it enters dormancy.
Milkweed
Butterfly milkweed is a heat-loving bloomer whose seeds benefit from cold and moist stratification. As milkweed finishes blooming, collect seeds or let them drop naturally to expand the colony.
The vibrant blooms and sweet nectar attract important pollinators like monarch butterflies and beneficial insects. Milkweed is a food source for monarch caterpillars and shelter for their chrysalis.
Scatter seeds generously to create large patches. Monarchs rely on masses of reliably blooming milkweed in the summer.
Aster
Asters, native to North America, have deep blue-purple ray flowers with contrasting yellow centers. Their late-season blooms last well into fall and bring an infusion of color. They benefit bees and other pollinators with their blanket of nectar-rich flowers.
In mild climates, sow aster in late summer for winter flowering. In colder zones, sow them after spring’s last frost. Some species benefit from a period of cold stratification. Do some research to determine if it’s best to sow the species you’ve selected ahead of winter’s freeze.
Asters prefer moist, organically rich soils with good drainage. To prevent foliar diseases, allow plenty of air circulation.
Anise Hyssop
Anise hyssop is a showy native mint with purple-blue bloom spikes rising above gray-green, aromatic foliage. Its flowers are a rich nectar source for bees, butterflies, and hummingbirds.
Plant perennial hyssop seeds shallowly in September for spring germination, tamping them lightly for contact. They need light exposure to develop and benefit from a short chill period.
Suited for the herb garden and perennial bed, anise hyssop blooms profusely in summer through frost. The minty, anise-flavored leaves make refreshing iced or hot teas.
Beardtongue
Many species of Penstemon are native to the U.S. and widely cultivated because of their brilliant blooms and dark green foliage. Tubular blooms in shades of violet-blue to scarlet produce nectar that pollinators find irresistible.
Penstemons are long-lived, heirloom perennials tolerant of varying soil conditions and drought. They grow best in dry, light, well-drained soils. Seeds benefit from fall or winter sowing to allow exposure to cold temperatures and moisture.
Blue Flax
Flax is valuable for its seeds, oils, fibers, and flowers. These carefree, low-maintenance plants tolerate hot and cool weather and make good transitional-season growers.
Every cultivar produces edible seeds from deep crimson flowers. Direct sow perennial flax in September by scattering seeds on moist soil and gently tamping for contact and good light exposure. Plant them in late summer for fall and spring color. They reseed freely.
Echinacea
Echinacea is a favorite native with purple ray flowers surrounding a center of orange florets. It provides a prime nectar source for beneficial insects and is high-color with a long bloom season.
Purple coneflower flourishes in the summer heat and full sun in soils with good drainage. Plants reseed naturally. Let flowers go to seed to expand the colony and provide food for foraging birds.
If September in your area is very warm warm, wait until after the first heavy frost of fall to scatter this tough perennial’s seeds. They’ll benefit from a winter spent outdoors for successful growth. Those in milder climates can still enjoy these lovely blooms without cold stratification.
Gaillardia
Gaillardia, or blanketflower, brightens the garden in a riot of gold, orange, and red ray petals. Brown button centers contrast the bright rays.
Gaillardia blooms throughout the summer until frost and is a carefree performer with drought and heat tolerance. It grows in poor, sandy soils and adapts to various site conditions as long as the soil has good drainage.
The perennial seeds do not require special conditions to germinate, and do well with September-sowing in most climates. A tough native species, it’s a good one for a late winter direct sow in colder regions. In areas where it’s cold in winter, this plant is a resilient annual.
Liatris
Blazing star holds dense flowers in purples, pinks, and whites on tall, upright stems. Arching, fine-bladed foliage mounds and clumps beneath the leafy stems.
Liatris are native to North America, from Canada to Florida, depending on the species. Once established, blazing star is cold-hardy, withstands heat, and is drought-tolerant. It benefits from four to six weeks of cold and moist stratification from fall planting.
Lupine
Lupine enchants with lovely bell-shaped blooms in blues, purples, pinks, whites, yellows, and bicolors. These graceful ornamentals grow in various site conditions, including moisture fluctuations and less-than-ideal soils.
Lupine species are native to eastern North America (wild lupine) and western North America (meadow lupine). In addition to the striking blooms, palmate leaves form an attractive base.
Sow lupine seeds by scattering them in fall or winter. Snowfall provides insulation for overwintering. A cold, moist period is best for these hard-coated seeds.
Monarda
Beebalm is native to the eastern U.S. and is a favorite performer due to its hardy nature and outstanding scarlet blooms. Flared flowers cluster on stems above minty foliage. The bloom season is long, lasting from early summer through frost.
Plant seeds in September or October before the first autumn frost. Once established, monarda spreads by both seed and rhizome. Thin plants to control the spread. Monarda grows best in organically rich soils with consistent moisture and good air circulation.
Feverfew
Feverfew produces bushels of petite daisy-like flowers from early summer through frost. Foliage is feathery and aromatic, and plants have numerous herbal uses.
Sun-loving feverfew is easy to grow in moist, well-drained soils. Use feverfew in naturalized areas where it can reseed freely or deadhead spent blooms to prevent spreading.
Seeding feverfew in cold weather yields good germination results. Scatter the seeds of this perennial in September and lightly tamp them in, allowing exposure to sunlight.
