Fall is not typically the season that comes to mind when we think about putting new plants in the ground. Spring takes that title for me, and I imagine many folks share that notion. There are, however, some gorgeous perennial plants that perform great when you plant them in September and beyond, depending on your climate.
Many fall-blooming plants are perfect for late summer planting. This is when they are in their active growth phase, and are likely to establish roots quickly. Not to mention, the cooler soil and air temperature, paired with shorter days puts less stress on the plant.
September isn’t quite the time to start planting those things that go in the ground while dormant. It’s a great time to plant fall flowering plants and many spring bloomers that flower on old wood. Here are some perennial plants that you can put in the garden in September for color now and years to come.
Rose ‘Coral Knock Out®’
Knock Out ® roses are great for late summer and early fall planting. They are heat tolerant, so they will adapt even if the cool weather hasn’t arrived yet. The soil is still warm, and the water table is high, encouraging rose root development.
Get this shrub in the ground at least six weeks before your first anticipated frost date. ‘Coral Knock Out’ produces a bounty of bright coral, double petal flowers. It has great pest and disease resistance, especially to blackspot. Its ease of care is certain to please.
Forsythia ‘Lynwood Variety’
If you’re looking for a shrub that makes a bold statement in the landscape, forsythia is the top dog. You’ll be hard-pressed to find a brighter bush. You can plant Forsythia in fall or spring. In warmer climates, I would wait until a bit later in the season. In cool climates, September is a great time to plant this perennial.
Don’t prune this one in the fall because the buds form on old wood. Pruning too late in the year will reduce blooming. The ‘Lynwood Variety’ is spectacular. It’s a winner of the Award of Garden Merit from the Royal Horticultural Society. Fast-growing and low-maintenance, this shrub gives you a lot of bang for your buck. It has lovely fall foliage, as well.
If you live in northeast North America, check to ensure Forsythia x intermedia is not invasive in your area before planting.
Astilbe ‘Vision in Pink’
Astilbe should go in the ground at least eight weeks before your first expected frost date. This gives them time to establish roots before the cold comes. Give them a hefty layer of mulch to insulate the young roots. These plants bloom in summer, producing large plumes of highly textural flowers.
These make a nice plant for the more shaded areas of the garden. They grow to a solid height of two to three feet, making them great mid-ground perennials. ‘Vision in Pink’ has toothy foliage and wonderful, light pink flowers. It makes a great cut flower, and dries nicely, too.
Anemone ‘Honorine Jobert’
Anemones are members of the buttercup family, and they’re just as delicate and pretty as a picture. Their long stems and attractive flowers make them popular in floristry. Ideal planting should take place when the soil cools to about 60°F (16°C). In warmer climates, it’s better to wait a month or two longer.
Anemone bloom time varies according to species. ‘Honorine Jobert’ blooms in late summer for five to eight weeks, leading into fall. The tall flower sprays stand high above the dark green foliage, which has a purple tint. The flowers also have a slight blush, but appear white from a distance. This is another winner of the RHS Award of Garden Merit.
Daylily ‘Strawberry Candy’
Daylilies love a cool autumn day as much as the rest of us do. In warmer climates, you could wait a month to plant these. As long as the temperature is coming down, it’s prime time for daylilies.
Make sure to get these in the garden at least four to six weeks before the first frost. Give them a thick layer of mulch to regulate the temperature of the soil. Give them a bit of fertilizer, too.
‘Strawberry Candy’ is a stunner. The narrow, strap-like foliage forms attractive clumps that look nice nearly year-round. The blooms are large and apricot colored. A red, heart-shaped pattern toward the center resembles a large strawberry.
Helleborus ‘Ivory Prince’
Also known as Lenten roses, hellebore is the rose of the winter garden. They have very few issues to contend with and make an ideal addition to shaded areas in the yard. September is a good time to plant perennials these in cooler climates. Make sure to leave four or five weeks before that frost date.
Hellebore is a winter bloomer and an evergreen. Their basal clump of deep green foliage will keep things looking alive in the cold weather. ‘Ivory Prince’ has soft, pale green to ivory flowers with a cool blush here and there. Diverse hellebore varieties add a cozy woodland vibe wherever you put them.
Rudbeckia ‘Chocolate Orange’
Rudbeckia greatly benefits from vernalization, which is an initial period of cool temperatures, to become established. This helps them to form strong roots, which will result in larger, stronger flowers. You can plant starts, or drop seeds in the garden now.
There are many varieties of rudbeckia, all in warm shades. The classic yellow-petaled black-eyed Susan has a charming wildflower vibe. ‘Chocolate Orange’ is fancier, with a deep red center that fades to bright orange at the ends of the petals.
Azalea ‘Rosy Lights’
Autumn planting is just right for azaleas. Cool weather and long nights, paired with more regular rainfall are the perfect conditions for establishing roots. Their roots will continue to grow in soil down to 40°F (4°C), so give them some mulch to keep them growing late in the year.
‘Rosy Lights’ took home the Rhododendron of the Year Award from the American Rhododendron Society. It’s a mid-sized shrub that blooms on bare wood. The flowers are large, bright coral, and trumpet-shaped. They are a favorite food for pollinators in the spring.
Phlox ‘White Delight’
September is a great time to plant perennial phlox, even in cold climates. As long as they have about one month to establish roots, they should be ready for the winter. Make sure to keep them moist during that first month, and give them some mulch before the first frost.
‘White Delight’ is perfect for the border. This creeping phlox stays low to the ground and creates a lovely carpet of foliage. In late spring, small, delicate, fragrant flowers cover the carpet of green, lighting up your beds and borders. Naturally, ‘White Delight’ has pure white blooms with a tiny yellow eye.
Sedum ‘Autumn Joy’
In cool climates, make sure to get your sedum in the garden by the end of the month. It needs ample time to establish roots but will appreciate the cooler weather while it does so. If you’ve still got plenty of warm temperatures on the horizon, it’s still a good time to grow sedum.
‘Autumn Joy’ is probably the most popular variety of sedum, which is also known as stonecrop. It’s won the Award of Garden Merit twice and has excellent heat, cold, pest, and disease resistance. What more could you want?
Tickseed ‘Moonbeam’
Perennial tickseed is very cold tolerant. In fact, it will survive a frost. I’ve seen them retain their foliage after several nights of temperatures in the 20s (~-7°C). Plant them now to help them get established before winter, they will hold their foliage longer this way.
‘Moonbeam’ won the 1992 Perennial Plant of the Year Award, making it extra special. It’s known to be an excellent performer, forming a lush mound of foliage that’s covered in lemon-yellow flowers for most of the summer. It works well in beds and containers.
Coneflower ‘Secret Affair’
If you have six weeks to spare before the first freeze rolls in, you have time to plant coneflowers. They need this amount of time to establish roots, so they will return in the spring. These long bloomers are great for the pollinator patch, and they make long-lasting cut flowers.
‘Secret Affair’ is no average coneflower. Its voluminous flower heads practically glow in neon pink. There is no keeping them a secret. Unlike the standard, single-petal form flowers common in nurseries, these are much showier. They have a large, rounded cluster of petals covering their spiky cone.
Helenium ‘Waltraut’
Helenium, also known as sneezeweed, is a great perennial to directly sow in the garden in fall. In cooler climates, September is a good time, in warmer ones, hold off until the soil cools off. Simply sprinkle these seeds on moist soil, two to three weeks before your first frost.
This is another plant that likes vernalization. The seeds need to experience some cold weather to germinate. Once they do, you will adore these pretty flowering perennials. In areas without frost, you can simulate this process in your refrigerator. They are so easy to care for! ‘Waltraut’ has lovely brown eyes and brick-red petals tipped with the slightest bit of yellow.
Coral Bells ‘Palace Purple’
Fall planting is perfect for coral bells, and they love a partially shaded area in the garden. Four hours of morning sun is about perfect for these leafy perennials. They should go in the garden about four to six weeks ahead of the first freeze, at least.
Protect your coral bells’ roots during winter with a heavy layer of mulch. The young plants will appreciate this insulation. ‘Palace Purple’ is a popular variety with large, star-shaped leaves in shades of green, brown, and, you guessed it—purple! When they bloom, coral bells are attractive to butterflies.
Chrysanthemum ‘Clara Curtis’
Chrysanthemums are perfect for fall planting. They can go in the ground as soon as the weather begins to cool, preferably while they’re still blooming. Give them at least six weeks to establish before winter. Mid-September is ideal in most places.
‘Clara Curtis’ is famous for her early and bountiful display of flowers. The blooms are large and daisylike, with soft, pink ray petals and a cheerful, yellow eye. This variety also goes by the name ‘Country Girl.’ Water your mums at the soil level to avoid fungal issues on the foliage.
Hosta ‘Fire and Ice’
Hostas make beautiful borders in partially shaded areas. Some tolerate full exposure, but the afternoon sun can burn the pretty leaves. The sweet spot for planting these perennials is while the soil is warm and the air begins to cool. Give them at least three weeks before the first freeze, more if possible.
There are so many excellent varieties to choose from. Different colors and variegation mix wonderfully. ‘Fire and Ice’ is a variegated hybrid. The leaves are deep green and creamy white, with a high contrast between the two. It’s a smaller variety and a winner of the RHS Award of Garden Merit.
Peony ‘Pink Hawaiian Coral’
Late September is perennial peony planting time. Though, in warmer areas, you can plant all the way into November. Fall-planted peonies tend to have a stronger constitution in general. Planting in the spring can add an entire year of lag time in your peony’s growth.
It’s hard to select just one peony to grow. They are such spectacular bloomers. ‘Pink Hawaiian Coral’ flowers heavily and has strong stems, perfect for cutting. Pink to coral petals surround a dense cluster of golden stamens. These are a standout in any garden.
Iris ‘Royal Storm’
September marks the end of iris planting season, so if you don’t have your perennial bulbs yet, order some now. These bulbs, like many others, need some cold weather to grow. Planting them while the soil is still warm will help them to establish some roots before the cold sets in.
There are an amazing number of varieties of bearded irises. The color combinations seem endless. ‘Royal Storm’ is an award-winning variety with bi-colored petals. Pale lavender, and deep violet, deeply ruffled petals adorn the ends of tall, slender stems.
Ranunculus ‘Pink Picotee’
Ranunculus is a warm-climate perennial that is sometimes grown as an annual in cooler climates. If you live north of Zone 8, plant these in the spring and then dig up the corms when they die back in summer. In Zones 8-11, fall planting is best.
You can hold off on planting this perennial until late fall if you prefer, but any time between September and December should work. I adore the tight rosettes of petals that make up these beautiful blooms. As cut flowers, they are surprisingly sturdy as long as you cut them in the bud. ‘Pink Picotee’ has buttery petals rimmed with varying shades of pin.
