Aster

Lighting up the late-season landscape with its deep violet to lavender-pink blooms, asters provide color and contrast to the fall perennial border front. These nectar-rich flowers are a pollinator favorite. If the plant's height needs to be controlled, pinch back the stems before mid-July to delay flowering and help decrease the need for staking.

Season of Bloom: Late summer to fall

Growing Conditions: Full sun and moist, well-drained soil

Size: Up to 6 feet tall

Zones: 4-8

Baptisia

Also called blue false indigo for its blue springtime flowers, baptisia is a native prairie plant with deep roots. It's one of the best perennial flowers for clay soil since it can push through clay soil's dense texture. Other selections extend baptisia's color range to white, yellow, and purple. Its lupine-like flowers turn into blackened seed pods which are often used in dried flower arrangements.

Season of Bloom: Late spring

Growing Conditions: Full sun to part shade and well-drained soil

Size: Up to 4 feet tall

Zones: 3-9

Bee Balm

An old-fashioned favorite perennial, bee balm features brightly colored flowerheads in shades of red, pink, lavender, and purple that resemble unkempt mopheads. This fragrant plant is attractive to bees, hummingbirds, and butterflies, particularly when grouped in mass plantings. It's also one of the top rabbit-resistant plant choices for your garden.

In small garden settings, some varieties of bee balm can out-compete less aggressive neighbors, so be careful where you plant them.

Season of Bloom: Summer

Growing Conditions: Full sun to part shade and moist, well-drained soil

Size: Up to 4 feet tall

Zones: 4-9

Black-Eyed Susan

A summer staple for sunny borders, black-eyed Susan is one of the most popular garden perennial flowers. Its daisy-like yellow flowers that grow up to 4 inches in diameter are an excellent addition to perennial borders, cottage gardens, prairies, or naturalized areas. 'Goldsturm' is among the most popular varieties for its vigorous growth and profuse blooms. It spreads quickly, but not invasively, to fill a planting bed with long-lasting color.

Season of Bloom: Early summer

Growing Conditions: Full sun and well-drained soil

Size: Up to 3 feet tall

Zones: 3-9

Blazing Star

A must-have perennial for butterfly gardens, blazing star is a native prairie plant that has become a popular cut flower. It offers spikes of fluffy, deep purple flower heads atop leafy flower stalks. This plant is an attractive addition to containers, cutting gardens, flower beds, and naturalized plantings.

Season of Bloom: Summer

Growing Conditions: Full sun and well-drained soil

Size: Up to 4 feet tall

Zones: 3-8

Bluestar

Native threadleaf bluestar adapts to most growing conditions, from soggy sites to dry clay and full sun to part shade. It shines in late spring with steel-blue, star-shaped flowers and again in fall when the lustrous feathery foliage turns bright gold. After flowering, consider cutting back stems to promote bushy growth.

Season of Bloom: Late spring

Growing Conditions: Full sun to part shade and well-drained soil

Size: Up to 3 feet tall

Zones: 5-9

Canna

Tropical-looking canna offers dramatic foliage and bright blooms. Its colorful flower spikes sit atop stems with large paddle-shaped leaves. Look for a wide range of varieties—some grow only 2 feet tall; others tower over 6 feet. This perennial grows well in poorly drained soils and even tolerates standing water, but it requires some extra plant maintenance to keep it healthy and tidy.

Season of Bloom: Summer

Growing Conditions: Full sun and well-drained soil

Size: Up to 8 feet tall

Zones: 7-10

Common Yarrow

The beautiful yarrow is one of the best perennial flowers for clay soil and can easily thrive in hard-to-grow spaces in your garden. Yarrow is tolerant of drought and heat and excellent for fresh-cut and dried flowers. Its fern-like, silvery-gray foliage and clusters of golden-yellow blooms are especially attractive to butterflies.

Season of Bloom: Summer

Growing Conditions: Full sun and well-drained soil

Size: Up to 2 feet tall

Zones: 3-8

Coral Bells

If you want to add color to your garden, coral bells or alumroot will provide impressive flower colors ranging from white and pink to light coral and deep red. The perennial gets its name from its spikes of tall, bell-shaped blooms, but it's highly recognized for its attractive foliage colors, with shades ranging from deep purple to bronze, peach, and silver.

Season of Bloom: Summer

Growing Conditions: Full sun to part shade and well-drained soil

Size: Up to 2 feet tall

Zones: 4-9

Coreopsis

The long-blooming summer perennial flower, coreopsis, is a superb border plant that makes a great cut flower. With their bright and cheery little blossoms, coreopsis can be great companion plants to ornamental grasses and other tough annuals and perennials, especially in containers. It grows in dense, bushy clumps, and it has yellow, daisy-like flowers with yellow center disks. Deadhead spent flower stalks to encourage additional blooms and to prevent unwanted self-seeding.

'Zagreb' threadleaf coreopsis, shown here, has fine feathery foliage and spreads to make an effective sun-loving groundcover in heavy clay soil.

Season of Bloom: Summer

Growing Conditions: Full sun and well-drained soil

Size: Up to 3 feet tall

Zones: 3-9

Daylily

A highly adaptable perennial flower for clay soil, daylily is easy to grow in gardens, borders, and edging. True to its name, daylily's trumpet-shaped blooms each last only a day, but plants can remain in flower for several weeks because they produce so many flower buds. With blooms up to 8 inches across in a variety of colors and textures, it's no wonder there are more than 60,000 cultivars registered with the American Hemerocallis Society.

Season of Bloom: Spring to late summer

Growing Conditions: Full sun to part shade and well-drained soil

Size: Up to 3 feet tall, depending on variety

Zones: 3-10

False Sunflower

It's hard to beat false sunflower, also called oxeye daisy, for garden performance. This tough perennial blooms all summer and boasts impressive heat and drought tolerance. This clump-forming, sunflower-like plant features daisy-like flowers and resembles the actual sunflower. The dwarf false sunflower variety, 'Tuscan Sun', remains under 3 feet tall and is perfect for small-space gardens.

Season of Bloom: Summer

Growing Conditions: Full sun and well-drained soil

Size: Up to 6 feet tall

Zones: 3-9

Fountaingrass

A fast-growing perennial, fountaingrass offers fluffy, burgundy-purple flowers in bottlebrush-like spikes that gracefully arch outward from a mounded plant. The plant shape resembles water spraying from a fountain, hence its common name. This low-maintenance ornamental grass provides excellent texture, color, and contrast to borders and open areas. 'Hameln', pictured here, is a dwarf variety that grows about 2-1/2 feet tall and wide.

Season of Bloom: Midsummer to fall

Growing Conditions: Full sun to part shade and well-drained soil

Size: Up to 5 feet tall

Zones: 9-10

Goldenrod

Known for its bright yellow flower spikes, goldenrod lights up gardens when it blooms in late summer to fall. It's very attractive to bees and butterflies and also makes for a good cut flower. Goldenrods are generally good flowers for clay soil and they can grow up to 5 feet tall. 'Crown of Rays' is just as pretty but stays more compact at 2 feet tall.

Season of Bloom: Midsummer to fall

Growing Conditions: Full sun and well-drained soil

Size: Up to 2 feet tall

Zones: 4-8

Hosta

A favorite in the shade garden for its attractive foliage, hostas are an ideal low-maintenance garden perennial. Many hostas produce pretty spikes of white or lavender blooms. This popular perennial can be grown as a groundcover or mixed with other perennials in shady borders, shade gardens or woodland gardens. 'Patriot' hosta, pictured at left, has blue-green leaves dramatically edged in pure white.

Season of Bloom: Summer

Growing Conditions: Part shade to full shade and well-drained soil

Size: Up to 3 feet tall (5 feet with flowers)

Zones: 3-8

Ironweed

With a name like ironweed, you know that this perennial flower for clay soil is tough. It tolerates summer heat and withstands long periods of drought. In late summer, it bears purple flowers that attract butterflies. This tall, coarse perennial with tough stems is a great background plant for borders.

Season of Bloom: Late summer

Growing Conditions: Full sun and moist, well-drained soil

Size: Up to 6 feet tall

Zones: 5-9

Little Bluestem

A gorgeous ornamental grass from the North American prairies, little bluestem bears blue-green foliage that turns crimson in fall. Purplish-bronze flowers appear on branched stems above this plant's foliage, followed by clusters of fluffy, silvery-white seed heads.

Season of Bloom: Late summer to late winter

Growing Conditions: Full sun and moist, well-drained soil

Size: Up to 4 feet tall

Zones: 3-9

Perennial Geranium

The most common species of geranium grown in the United States, perennial geranium makes an excellent groundcover on sites with clay soil. Also called bloody cranesbill for the crane-like shape of its seedpods and crimson flowers, this plant grows in a mound with white-hairy trailing stems that spread up to 2 feet wide. After the first fall frost, the foliage usually turns an attractive shade of red.

Season of Bloom: Late Spring

Growing Conditions: Full sun to part shade and well-drained soil

Size: Up to 18 inches tall

Zones: 4-8

Purple Coneflower

A butterfly-and-bird magnet for sunny sites, purple coneflower is an easy-to-grow perennial native to many prairies, meadows, and woods in the United States. Its showy daisy-like flowers bloom atop stiff stems with dark green leaves that make a great fresh-cut bouquet. 'Ruby Star', pictured here, is one of many varieties available. Also, look for hybrids with colors ranging from pink to white, orange, burgundy, and red.

Season of Bloom: Summer

Growing Conditions: Full sun to part shade and well-drained soil

Size: 3-5 feet tall

Zones: 3-8

Russian Sage

Russian sage is a woody-based perennial of the mint family with aromatic gray-green leaves on square stems and whorls of light blue flowers tiered in branched panicles. Its wispy lavender flower spikes and silvery foliage make it an anchor of the summer border. Russian sage grows so well in hot, dry, sunny clay that it's considered aggressive in some areas, so check local restrictions before planting it.

Season of Bloom: Midsummer

Growing Conditions: Full sun and well-drained soil

Size: Up to 5 feet tall

Zones: 5-9

Sea Holly

If you're looking to add texture to your landscape, consider adding sea holly to your flower beds and borders. This perennial offers jagged leaves with clusters of steel-blue flowers surrounded by a crown of spiny-looking bracts and has become popular in cut floral arrangements. Related to thistles (though it doesn't spread like them), sea holly is also deer- and rabbit-resistant. Rattlesnake master and Miss Willmott's ghost are other types of Eryngium that are good perennials for clay soil.

Season of Bloom: Summer

Growing Conditions: Full sun and well-drained soil

Size: Up to 3 feet tall

Zones: 5-9

Sedum

The drought-resistant perennial flower sedum is an excellent plant for rock gardens or border fronts. It features masses of tiny, star-like flowers which emerge pink, gradually change to deep rose-red, and then change to coppery-rust in the fall. The flattened heads of flowers sit atop stems of grayish-green, succulent-like leaves and are attractive to butterflies throughout the season.

Season of Bloom: Fall

Growing Conditions: Full sun and well-drained soil

Size: Up to 2 feet tall

Zones: 3-9

Switchgrass

Among the most versatile of ornamental grasses, switchgrass thrives in moist, dry, or clay soil—and even in part shade. It offers wispy seedheads that sway gracefully in the breeze. Some varieties, such as 'Heavy Metal', have bluish-green foliage; others turn shades of red and maroon in autumn.

Season of Bloom: Summer to winter

Growing Conditions: Full sun to part shade and moist, well-drained soil

Size: Up to 6 feet tall

Zones: 5-9

Yucca

Also called Adam's needle for its sharp, pointed leaves, yucca shines in the early summer garden when it sends up a towering candle of waxy white blooms. Perfectly at home in desert climates, yucca is also a good perennial flower for clay soil in more humid regions. Plant it as an architectural accent in your garden, or watch it thrive in a large container.

Season of Bloom: Summer

Growing Conditions: Full sun and well-drained soil

Size: Up to 8 feet tall

Zones: 5-10