15 Perennials You Can Plant This September

Are you looking to add some perennial flowers to your garden this September? There are plenty of perennials that can be planted in the fall, and bloom in the spring. In this article, gardening expert Jill Drago examines 15 of her favorite perennials to add to your garden in September.

September Perennials

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September is a wonderful time to add new perennial plants to your garden. The weather is typically cooling down, and there will be plenty of time for the plants to establish themselves before the cold winter arrives.

There are many benefits to planting in September. The soil is still warm and will encourage healthy root growth which is the main goal when hoping your plants will make it through the winter. Don’t forget to water as you normally would, even if the temperatures are cooling down.

The best perennials to add to your garden are the ones that early flowering perennials that bloom in the spring. Planting in September is ideal as it will allow the your plants time to get established before the winter frost so they can flower when spring arrives. Let’s dig into some of my favorite perennials that are sure to add to the beauty of your garden this month!

Allium

Purple Flowers Growing in a Sphere Shape
Allium blooms in purple, blue, white, pink, and sometimes yellow globe-shaped heads.
Scientific Name: Allium spp.
  • Plant Size: 1-6 feet, varies greatly between species
  • Sun Exposure: Full Sun
  • Bloom Time: Spring
  • Plant Zone: 4-10

Planting these ornamental onion plants in the fall is my favorite way to add a big spring impact to your gardens. There are many different varieties of allium in many different sizes. You may be most familiar with the very large globe flowers that are the perfect purple sitting on one tall stalk. But there are other shorter varieties with more attractive foliage and less dense florets.

These plants have an onion-like odor to them, making them excellent companion plants in many gardens as this scent is great at keeping wildlife out of your garden.

When these plants are done blooming they don’t have much to offer, so be sure to plant them behind some perennials or shrubs if you are worried about the yellowing foliage that comes with a bulb.

Artemisia

Shrub With Small Yellow Flowers and Silver Foliage
The silvery foliage of artemisia is a beautiful addition to perennial gardens.
Scientific Name: Artemisia spp.
  • Plant Size: 1-5 feet tall
  • Sun Exposure: Full Sun
  • Bloom Time: Summer to fall
  • Plant Zone: 3-10

This is a very large genus that is grown primarily for its soft silver foliage. These plants are tough, and thrive in sunny and dry areas, adding gentleness to hot weather gardens that may need some softening.

Use caution when selecting a planting site for artemisia because it is known to be highly toxic to pets, and mildly toxic to humans. Give these plants a final haircut in the fall, and be ready for them to return in the springtime. Enjoy these low-maintenance plants in your gardens or even in containers.

Beardtongue

Pink Penstemon Flowers Growing in a Sunny Garden
Commonly grown in shades of purple, beardtongue also comes in pink, white, red, and yellow.
Scientific Name: Penstemon spp.
  • Plant Size: 1-3 feet
  • Sun Exposure: Full sun
  • Bloom Time: Spring through summer
  • Plant Zone: 3-8

This pretty herbaceous perennial is a member of the same family as foxglove, the plantain family. Beardtongue will begin to bloom at the end of the spring, nicely filling in the gap after your spring bulbs have faded and your summer perennials have begun to bloom. The tube-shaped flowers appear on spiky flower stems, and the foliage is lance-shaped.

Deadhead these flowers after they have bloomed to neaten your garden as well as lengthen the blooming time. Beardtongue comes in shades of purple, red, pink, white, and even the occasional yellow. These perennials do best in rocky or sandy soil and can tolerate some summer drought.

Blazing Star

Purple Liatris spicata Flowers Blooming in a Garden
The tall spikes of purple or white blazing star flowers grow to be up to 4 feet high.
Scientific Name: Liatris spicata
  • Plant Size: 2-4 feet
  • Sun Exposure: Full sun
  • Bloom Time: Summer to Fall
  • Plant Zone: 3-9

Blazing star, also known as Liatris, is a great plant if you are looking to add something a little different to your gardens. These perennials have grass-like foliage, but their flowers are quite unlike any other plant. The blooms are a spike that is covered in tiny star-like flowers of either purple or white.

Blazing star is native to North America, which makes it a great choice if you are looking for a low-maintenance, drought-tolerant plant. These perennials are low maintenance, needing only the occasional trim. You can deadhead the blooms and foliage once they brown, or you can leave them in your garden for some fall interest.

Gaillardia

Orange and Yellow Blanket Flowers Blooming in a Sunny Garden
The daisy-like petals of the gaillardia, or blanket flower, start as orange and fade to a bright yellow at the tips.
Scientific Name: Gaillardia x grandiflora
  • Plant Size: 2-3 feet
  • Sun Exposure: Full sun
  • Bloom Time: Summer- Fall
  • Plant Zone: 3-10

Gaillardia is also commonly known as a blanket flower. This perennial is easy to grow and loves hot weather and is very tolerant of poor soil. The flowers of gaillardia come in many colors but the most popular is probably the bright red, orange, or yellows.

Gaillardia does not need to be deadheaded but will continue to rebloom all summer and through the fall. This plant is native to North America and makes a great addition to a low-maintenance garden. Plant this perennial in borders or containers, you will love it no matter what.

Gaura

Pink and White Whirling Butterflies Flowers Blooming in a Garden
If you are looking for a low-maintenance and beautiful September perennial, guara is an excellent option.
Scientific Name: Gaura lindheimeri
  • Plant Size: 2-3 feet
  • Sun Exposure:
  • Bloom Time: Summer to Fall
  • Plant Zone: 5-9

Guara, known to many as Whirling Butterflies, is a really pretty plant. Its original form was invasive but it has since been hybridized to be more manageable in our garden beds. Gaura does have a taproot and does not like to be moved, so if you love this plant be sure to choose a location that you will be happy with for many years to come.

This perennial looks to me a lot like ornamental grass with sweet white or pink flowers sort of dancing on the reeds. It’s great used as a backdrop in a perennial garden, or in a xeriscape because it is quite low maintenance.

Heather

Pink Calluna vulgaris Flowers in Evening Sunlight
Heather blooms in pretty pink to white flowers and the foliage turns purple-bronze in color when cooler weather arrives for multi-seasonal color.
Scientific Name: Calluna vulgaris
  • Plant Size: 2 feet
  • Sun Exposure: Full to partial sun
  • Bloom Time: Midsummer to Early Fall
  • Plant Zone: 4-6

You may know this plant by Scotch Heather, and if you don’t, it is an important hint to how to care for this plant. Heather is native to Scotland and is found beautifully decorating the moors. This plant is great in coastal climates and prefers moist, well-draining soil.

Heather grows in a nice mounded form and is slow growing. Its flowers are white or a mauve pink and spiked in nature. The foliage will offer pretty autumnal color as the temperatures cool.

Helianthus

Yellow Perennial Sunflower Up Close
Bright and cheery, this yellow flower is often referred to as the perennial sunflower.
Scientific Name: Helianthus spp.
  • Plant Size: 3-10 feet, species dependant
  • Sun Exposure: Full Sun
  • Bloom Time: Midsummer- Fall
  • Plant Zone: 4-8

Helianthus, or the perennial sunflower, is a great addition to any full sun garden. Its growth habit is whimsical and it keeps the beauty of sunflowers in your garden all summer long. Helianthus is an easy-to-care-for perennial that grows beautifully, even in poor soil.

Unlike the annual sunflower, this September perennial is multi-stemmed. Each stem has at least one flower on it, growing along a central stem. The blooms arrive in midsummer and die off in the fall or at the first frost.

Hosta

Purple Flowers Blooming From Long Stems and Lush Green Foliage
There are many varieties of hosta that can suit your garden’s aesthetic.
Scientific Name: Hosta spp.
  • Plant Size: 6 inches – 4 feet, varies greatly with species and variety
  • Sun Exposure: Full to partial shade
  • Bloom Time: Summer
  • Plant Zone: 3-9

If you are looking to bump up the beauty of your shaded gardens, hostas are a perfect solution. These perennials come in a variety of sizes, as well as hues. While most of them are green, they will come in variations with swirls of white.

The flowers of hostas are tube-shaped and are either white or purple. Plant your hostas on a border, or speckled throughout your shady perennial gardens. You can’t go wrong with these September perennials that come back consistently year after year!

Lavender

Bee Pollinating Purple Lavandula Flowers
Lavender attracts pollinators, such as bees, to the garden, making is a good choice as a companion plant.
Scientific Name: Lavandula spp.
  • Plant Size: 2-3 feet
  • Sun Exposure: Full Sun
  • Bloom Time: Summer
  • Plant Zone: 5-10

Lavender is a very well-known herbaceous perennial known both for its beautiful flowers as well as their calming aroma. In its native region of the Mediterranean, lavender grows in rocky areas. This makes it a great choice for areas that may experience drought or have less fertile soil.

Take care when you are choosing your lavender variety, their growing conditions vary, and choosing the incorrect plant will lessen your success with this beautiful plant. Lavender is useful for keeping deer away and is an excellent companion plant for just about anything in your garden.

Lenten Rose

White and Purple Hellebore Flowers Up Close
These beautiful flowers tolerate winter conditions and do not like summer heat.
Scientific Name: Helleborus x hybridus  
  • Plant Size:  12-18 inches
  • Sun Exposure: Partial Sun
  • Bloom Time: Early Spring
  • Plant Zone: 4-9

If you are looking to add spring-blooming perennials to your garden, give the lenten rose a try. The Lenten Rose is a really pretty bloomer that could begin flowering as early as late winter or spring depending on where you live.

Lenten rose flowers are available in a large variety of colors from white, pink, red, or purplish-black. This plant has attractive evergreen foliage, meaning you don’t even need to cut this perennial back unless the flattened foliage bothers you. 

Lily Turf

Purple Flower of Liriope muscari Blooming From Grassy Foliage
Lily turf makes an excellent low-growing option for planting along the edges of gardens, as long as it is maintained.
Scientific Name: Liriope muscari
  • Plant Size: 12-15 inches
  • Sun Exposure: Partial Sun
  • Bloom Time: Summer
  • Plant Zone: 5-11

This is a group of fun perennials that are grasslike with small spiked flowers. The foliage is deep green and lush, and the flowers can range from purple, pink, or white. This is an excellent plant to use as a border, or in an area where you are looking to prevent erosion.

Lily turf will grow and spread quickly, so take care to plant it in an area that has enough space for its growth habit. This is a great low-maintenance plant for new gardeners that are looking for a great impact.

Monkshood

Tall Purple Aconitum napellus Flowers in a Sunny Garden
Add colorful height to your garden by planting monkshood this September.
Scientific Name: Aconitum napellus
  • Plant Size: 2-5 feet
  • Sun Exposure: Partial sun
  • Bloom Time: Summer to fall
  • Plant Zone: 3-8

Monkshood is a beautiful tall perennial with gorgeous colorful blossoms that will accent your shade gardens perfectly. Before we get into the details of monkshood it is important to remember that monkshood is toxic to humans as well as pests, so be careful where you plant this perennial. It’s well acclimated to lower light conditions, making a great shade-friendly perennial.

The flowers can range from a bluish purple, pink, white, and even yellow. Plant monkshood in an area with well-draining soil that can remain moist, possibly alongside your hostas or hydrangeas!

Rose of Sharon

Pink Hibiscus Flowers Blooming in a Garden
Otherwise known as hibiscus, the Rose of Sharon adds a tropical feel to gardens in zones 5-8.
Scientific Name: Hibiscus syriacus
  • Plant Size: 8-12 feet
  • Sun Exposure: Full to partial sun
  • Bloom Time: Summer to Fall
  • Plant Zone: 5-8

Rose of Sharon is a relative of those tropical hibiscus flowers you see on your tropical vacation, or may plant as an annual, and also as a perennial. This shrub is a hardier version of those plants. These shrubs are woody and can grow quite tall if you don’t prune them back.

The flowers come in more subtle hues of white, pink, purple, and blue all of which feature a darker throat than the petals. This shrub can grow almost anywhere and once they are mature they don’t require much care at all. Prune for shape, and pull young seedlings if you wish!

Sea Holly

Blue Eryngium planum Flowers Blooming in Evening Sun
The unique sea holly is a delightful perennial that blooms for many months.
Scientific Name: Eryngium planum
  • Plant Size: 2-3 feet
  • Sun Exposure:  Full sun
  • Bloom Time: Summer to Fall
  • Plant Zone: 5-9

Sea holly is a really interesting perennial that you should try adding to your sunny and hot garden. The flowers of sea holly are purple or white, and spiky. They remind me of globe thistle, surrounded by decorative petals that are spiky.

These flowers will stay in bloom for a long time. Sea holly is a low-maintenance perennial that prefers sandy soil and does not need much water.

Final Thoughts

Get out in your garden in the beautiful month of September. The weather will be cooling down, and your plants will be very happy about that. Try adding some beauty to your gardens that you will be able to enjoy for years to come! Give one of these September perennials a try, I promise you won’t be disappointed.

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