17 Perennials to Plant in August

With many regions experiencing heat waves, August in the garden is a time for trimming crispy stems, plucking spent annuals, and deadheading perennials to encourage a late-season flush of flowers. Many plants are still in full swing or at least gearing up for their late summer and early fall burst of energy.

Depending on the climate, August temperatures and weather can bring extremes. You can still add perennials to the collection and fill in any gaps, with regular attention to moisture and light requirements. For large installations, it’s best to wait until the dog days of summer are behind us, as temperatures mellow. 

To plant perennials in August, avoid particularly hot spells. Plant early in the day for the least stress on new transplants and the most moisture uptake. Give your new plantings extra water as they get established under the summer sun.

Our list of late-summer additions has showy characteristics that extend into fall. Given proper cultural requirements, these easy-going perennials are the most likely to adapt to varying climatic conditions. Enjoy the color and buzz surrounding the resilient selections. 

Scarlet Rose Mallow

	common name Scarlet Rose Mallow
	botanical name Hibiscus coccineus
	sun requirements Full sun to partial shade
	height 6-8’
	hardiness zones 5-9

Scarlet rose mallow, or Texas star hibiscus features large scarlet flowers from mid-summer into fall. It is a perfect perennial for August planting. Five broad petals swirl around a showy central column of stamens. The red petals are more precisely cut and pointed than those of other mallows.

Texas star produces flowers on tall stalks lined with fine-textured leaves. Foliage is deep green and deeply palmate with serrated edges.

This mallow grows along roadside ditches, marshy areas, and wetland edges. It prefers moist soils but adapts to both wet and dry conditions. Provide supplemental moisture during dry spells for the best flowers, especially to nurture those planted in August.

Top dress with a thick layer of mulch for winter protection. The native mallows may withstand zone 5 temperatures with good insulation. Leave fading stems in place as plants enter dormancy for added protection.

Holly Fern

	common name Holly Fern
	botanical name Cyrtomium falcatum
	sun requirements Partial to full shade
	height 1.5-2’
	hardiness zones 7-10

These durable ferns have broad, dark green fronds with a lustrous finish. Each frond has coarse leaflets that resemble holly leaves but with a soft texture. Like hollies, the perennials are evergreen (at least in warm climates).

Holly ferns make excellent specimens in shady raised beds with a lush, full form and arching fronds. These easy-to-grow ferns prefer rich soils with even moisture, though they withstand periods of drought once established. 

Holly ferns are evergreen in areas with mild winters and provide lasting seasonal interest. Let dormant fronds remain in place over the winter for added crown protection. Remove ragged fronds in spring as new growth emerges.

Japanese Anemone

	common name Japanese Anemone
	botanical name Eriocapitella hupehensis
	sun requirements Full sun to partial shade
	height 2-4’
	hardiness zones 4-8

These fall-blooming anemones shine in border plantings with buttercup blooms. The clump-forming perennial sends up tall stems with clusters of petals in pinks, purples, whites, and golds—hues that beautifully complement fall tones. The tissuey outer petals (actually sepals) frame a central cluster of tiny florets.

Eriocapitella hupehensis and hybrida are fall-flowering cultivars with single, semi-double, and double blooms. Some have extended bloom seasons and flower well into November. Deep, ferny foliage supports sprays of buds and wanding blooms.

Anemones must have good drainage to thrive. During the growing season, they prefer humusy, moist soils. Protect plants from drying winds and sun.

Chrysanthemum

	common name Chrysanthemum
	botanical name Chrysanthemum spp.
	sun requirements Full sun
	height 1-3’
	hardiness zones 5-9

Sometimes, I forget about the delicate-leaved chrysanthemums creating a lovely “filler” in the garden. The hardy garden mums grow patiently, offering a softly mounding cushion of leaves. Then, with autumn on the horizon, they produce a spectacular blanket of blooms in seasonal jewel tones. Scarlet, gold, orange, pink, or purple blooms cover the dark green lobed leaves.

Hardy chrysanthemums grow vigorously with upright or sprawling stems and a clumping habit. ‘Ryan’s Pink’ has lovely trailing stems and pale pink flowers. ‘Mrs. Robinson’ yields prolific pincushions of deep red. ‘Miss Gloria’s Thanksgiving Day’ has daisy-like rose pink flowers. ‘Coppersmith’ is bold in orange tones with a cushion form, ideal for cutting and arranging.

Easy-care chrysanthemums grow best in moist, organically rich soils. Planting these perennials in August might bring some blooming, but they’ll shine by next fall.

Caryopteris

	common name Caryopteris
	botanical name Caryopteris spp.
	sun requirements Full sun
	height 3-4’
	hardiness zones 5-9

Caryopteris (also Bluebeard or Blue Mist) offers an abundance of tiny blue flowers that rise in clusters above mounding foliage. The purple-blue tones in late summer and fall contrast highly with attractive foliage. Leaves are bright and full even when plants aren’t in flower.

Caryopteris x clandodensis creates a misty spray of blooms surrounding leaves. ‘Gold Crest’ has showy bright green-gold leaves, while ‘Emerald Crest’ features true green. ‘Blue Mist’ produces powder blue flowers, while ‘Dark Knight’ has deep royal purple petals above silver-blue leaves.

Look to C. divaricara ‘Snow Fairy’ for minty green leaves with a white margin. Deep lavender flowers create a pretty cloud above the crisp, light foliage.

Caryopteris grows well in average, medium-moisture soils. It prefers loose, light loams and sandy conditions and tolerates periods of dryness. It withers in wet soils that lack drainage. The mounding plants take shearing and shaping well and divide easily.

Epimedium

	common name Epimedium
	botanical name Epimedium spp.
	sun requirements Partial to full shade
	height 6-10”
	hardiness zones 5-8

Epimediums (also barrenwort and fairy wings) are low-growing, compact perennials that bring color, texture, and form to shady spots for multi-season appeal. Their colorful foliage has dramatic patterns with mottling, blotching, and venation.

Columbine-like flowers with delicate spurs emerge in summer. While an August planting misses the summer bloom, the foliage is a draw. It also allows plants to establish over the fall. 

Epimediums are low-maintenance and grow in conditions other perennials may find challenging, like deep and dry shade. They’ll need regular moisture on the tenuous dog days of summer. Plant them in August among other shade-loving perennials, such as ferns, astilbe, hellebore, wild ginger, columbine, bleeding heart, and hosta. 

Sage

	common name Sage
	botanical name Salvia officinalis
	sun requirements Full sun to partial shade
	height 1-2’
	hardiness zones 4-8

Sage is a favorite herb with velvety silver leaves and an earthy scent. The Mediterranean plant withstands hot, arid summers and is ornamental in addition to its culinary value. These fragrant herbs make excellent rock garden and perennial border additions.

Common sage thrives in medium to dry soils—even poor ones—as long as they’re well-draining. It is both cold-hardy and heat-tolerant and grows across a range of climates.

Look for S. officinalis ‘Berggarten’ (also called ‘Herrenhausen’) for a variety with increased mildew resistance. It features broad, blue-gray leaves and lavender bloom spikes in summer. ‘Berggarten’ received the Royal Horticultural Society’s Award of Garden Merit for its ornamental value and landscape performance.

Fountain Grass

	common name Fountain Grass
	botanical name Cenchrus setaceus
	sun requirements Full sun to partial shade
	height 3-4’
	hardiness zones 9-11

Ornamental grasses are a signature of fall. They add texture, movement, and lasting seasonal interest. Pennisetum, available in various heights, colors, and hardiness levels, has thin, arching blades and showy plumes. 

The foliage and seed heads are showy even after the plants are dormant. For the best display, wait to cut back fountain grass until late winter before new growth emerges in spring. Or gently rake the grass with your gloved hand to remove dead leaves.

When choosing fountain grass, note that many varieties self-seed aggressively in optimal conditions and may become invasive, depending on your growing area.

The University of Georgia breeding program has several infertile options that won’t self-sow. ‘Hush Puppy’ is as cute as it sounds at three feet tall with fuzzy pink plumes that become tawny brown. ‘Cayenne’ has dark red bottlebrushes, and ‘Praline’ has sprays in pecan and taupe. 

However, there is a lot of discussion about whether or not sterile cultivars of invasive species have a negative impact on the surrounding ecology.  

Mexican Marigold

	common name Mexican Marigold
	botanical name Tagetes lemmonii
	sun requirements Full sun to partial shade
	height 4-6’
	hardiness zones 8-11

Mexican marigolds produce masses of yellow-gold ray flowers from late summer and fall until heavy frost. Their feathery, deep green foliage is aromatic. When other bloomers fade, Mexican marigolds bring a burst of color with single daisy-like flowers.

Mexican marigolds perennialize in moderate climates. They occur naturally from Arizona and northern Mexico, from mountains to canyons. They grow in clay and sandy soils. Drought tolerant, they’ll prefer moist, well-draining soils for the prettiest form and flowering.

Lemon Balm

	common name Lemon Balm
	botanical name Melissa officinalis
	sun requirements Full sun to partial shade
	height 2-3’
	hardiness zones 3-7

Lemon balm has lemony-scented leaves in fresh green. The mounding, spreading plants produce small bloom spikes in summer and fall. The foliage provides a burst of aromatherapy when brushed and is flavorful in beverages and dishes.

Grow lemon balm in rich soils with good drainage. They spread easily—at times aggressively—and reseed after flowering. Trimming and deadheading keep plants in check and promote a fresh flush of leaves. Lemon balm grows well in containers and raised beds to keep it from getting out of bounds. 

The resilient perennial herbs adapt to a variety of conditions (which is why they made the August list!). After your work in the late summer garden, enjoy a glass of iced lemon balm tea.

Santolina

	common name Santolina
	botanical name Santolina chamaecyparissus
	sun requirements Full sun
	height 1-2’
	hardiness zones 6-9

Lavender cotton, or santolina, is an Old World herb. It features aromatic silvery foliage, rugged adaptability, and acts as a low-growing, mounding ground cover. In the summer, santolina produces masses of golden yellow button blooms on stems rising above the foliage. 

This Mediterranean selection is evergreen and drought-tolerant when established. It’s well-suited to coastal exposure and hot summer conditions. It dislikes humidity—in humid zones, fungal diseases may be a problem.

Santolina grows best in average, well-draining soils that dry out between waterings. It adapts to various soil types, from sandy to clay to rocky. 

Agave

	common name Agave
	botanical name Agave americana
	sun requirements Full sun
	height 3-10’
	hardiness zones 8-10

Agave has broad, structural leaves in blue-green with sharp spines along margins and tips. After years of growth, it produces a single towering bloom stalk. While commonly called a century plant, it blooms in less than 100 years, typically between 10 to 30 years, but sometimes up to 80.

The desert flower is a 30-foot-tall thing of wonder. The showy bloom clusters of nectar-rich flowers draw a flurry of activity from pollinators. The unique stems produce new “pups” as the mother plant fades. 

Agave americana has uses that date back 8000 years when Aztecs employed plants for eating, tools, and more. Agave relies on warm climates and fast-draining soils to thrive, making it the perfect perennial for planting in August.

Bearded Iris

	common name Bearded Iris
	botanical name Iris x germanica
	sun requirements Full sun
	height 1-4’
	hardiness zones 3-9

The bearded iris literally “springs up” in the garden with spring flowers that last into summer. They repeat bloom and experience another flush in the fall.

The bearded iris bears large, ruffly flowers in a rainbow of colors. The blooms bring vertical interest with three upper and three lower petals (falls). Rich outer petals may have frilled edges or painterly washes. Centers often contrast the outer colors in bright white or yellow.

Irises tolerate various soil types, from acidic to clay to sand. They grow best in moist and well-drained conditions but are quite drought-tolerant. You may choose to divide iris colonies every few years and replant the divided rhizomes to expand the collection. August is one of the best times to plant and divide iris in temperate weather.

Stonecrop

	common name Stonecrop
	botanical name Sedum spp.
	sun requirements Full sun to partial shade
	height 3”-2’
	hardiness zones 3-9

Sedum, or stonecrop, is a heat-tolerant succulent that blooms in summer and early fall. Stonecrop offers multi-season appeal, whether a low ground cover or a tall, upright grower.

Hylotelephium ‘Autumn Fire’ is similar to the favorite ‘Autumn Joy.’ It has tighter branching, brighter, rosy pink blooms, and thicker leaves. Stout stems support loads of flat-topped flower clusters in fall.

Stonecrop is drought-tolerant and needs well-draining soil to thrive. The late-season flowers are a food source for bees and butterflies, followed by seeds for birds. Fresh and dried flower heads make a beautiful autumnal floral arrangement. Or, let them persist on the stem for extended interest in the seeds.

Muhly Grass

	common name Muhly Grass
	botanical name Muhlenbergia capillaris
	sun requirements Full sun
	height 2-3’
	hardiness zones 5-9

Muhly is an exceptional native ornamental grass. Its airy plumes create an intense pinky-red glow around fine-bladed foliage. Wiry leaves in deep, glossy green rest quietly until the panicle explosion in the fall.

Plant pink muhly in a mass to fully experience the ethereal purple haze. For white plumes, ‘White Cloud’ lives up to its name. The variety blooms after pink muhly and has an open habit with dense white plumes.

Low-maintenance, muhly grass is heat, humidity, and drought-tolerant. It grows in poor soils, including clay, rocky, and sandy. It’s also highly salt-tolerant.

Chelone

	common name Chelone
	botanical name Chelone spp.
	sun requirements Full sun to partial shade
	height 2-5’
	hardiness zones 3-8

Chelone is commonly called turtlehead because its flowers resemble a little turtle with an open mouth. Chelone is a storied Greek nymph who the gods turned into a turtle. She stayed home rather than attend the wedding of Zeus and Hera, and as punishment, she became destined to carry her home on her back.

But turtleheads are as pretty as their name is cute. They flower in white, pink, and red. Like snapdragons, they have two-lipped petals. They bloom from late summer to early fall. Leaves are dark green and shiny with toothed margins.

Chelone is native to North America and occurs naturally in bogs, swamps, and moist woodlands. It prefers moist, organically rich soils.

Joe Pye Weed

	common name Joe Pye Weed
	botanical name Eutrochium purpureum
	sun requirements Full sun to partial shade
	height 5-7’
	hardiness zones 4-9

Joe Pye weed is not as weedy as it sounds. Plants aren’t aggressive spreaders but are tall native perennials. They’re outstanding in a mass with large, domed flower clusters if you’ve got the room. Dwarf cultivars make them easy to fit into various garden spaces. 

While they grow in roadside ditches, the ornamental and ecological value benefits the native, pollinator, naturalistic, or rain garden. In summer and fall, purple-pink flowers with five flowers per cluster attract beneficial insects. Coarse, long leaves are dark green with purple-hued leaf nodes.

Seed pods last into winter and extend the interest.

These unfussy natives grow in different soil conditions, including clay. They thrive in rich, moist, well-drained conditions. To plant Joe Pye weed in August, ensure the transplants remain in moist soils.