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19 of the Best Flower Companion Plants for Dahlias

Mature size is 22 to 44 inches tall and wide. Shorter cultivars are suitable for flower beds and borders, while taller ones make excellent anchors for the back bed.

“Blue sky”

Agapanthus ‘Blue Heaven’ Bare Root is available from Burpee.

Our agapanthus growing guides include complete growing instructions. And you can learn more about 25 of the best agapanthus varieties in our roundup.

2. allium

Allium (Allium spp.) is a native perennial rhizomatous bulb with round flower heads composed of star-shaped flowers in shades of blue, green, pink, purple, red, white or yellow.

Perfect for zones 3 to 9, choose varieties that bloom in spring, summer or fall in full sun to partial shade.

Plants reach one to five feet tall with a spread of one to two feet. Mix or match dahlias for balloon-textured pops of color.


You can find ‘Serendipity’, a delightful purple cultivar, available from Nature Hills Nursery in no. 1.

For more information, see our complete guide on growing ornamental alliums.

3. Anise Hyssop

Perfect for zones 4 to 9, the multi-flowered blue, lavender or purple spikes of the native perennial anise hyssop (Agastache foeniculum) are a cheerful summer sight in full sun locations.

Maturing to heights of two to four feet with a spread of one and a half to three feet, they make a strong contrasting vertical statement among the rounded dahlia flowers.

anise hyssop seeds

You can find 100 or 250 milligram seed packets available from Botanical Interests.

See our anise hyssop growing guide for growing instructions.

4. Aster

Asters (Aster, Doellingeria, Eurybia, Ionaptis and Symphyotrichum spp.) Provide late summer to fall color in zones 4 to 8, where they thrive in full sun and tolerate dappled shade. Many are native species.

You’ll find an aster height for every need, ranging from six to 72 inches with a spread of eight to 36 inches.

In shades of blue, pink, purple and white, masses of small daisy-like flowers play a supporting role as a soft fill between the textures between or behind the bold central dahlias.

‘Alma Potschke’ is a New England aster that blooms with a profusion of bright pink flowers.

“Alma Potschke”

Find plants available at Nature Hills Nursery.

We have more guides to growing asters available for more information.

5. Bee balm

With petals like fireworks, the rich red, pink or purple hues of native perennial bee balm (Monarda spp.) pair well with the equally vivid hues of dahlias.

Suitable for full sun to partial shade locations in zones 3 to 9, this summer flower never disappoints with sturdy stems that rise three to five feet tall and a spread of 18 to 36 inches.

Monarda fistulosa bee balm

You can find purple flowered M. fistulosa seed packets available at Burpee.

Check out our bee balm growing guides for everything you need to know.

6. Black-eyed Susan

The native perennial black-eyed Susan (Rudbeckia hirta) has gold, orange or red petals surrounding dark brown central discs for streaks of crisp summer color in full sun in zones 3 to 9.

Photo by Nan Schiller.

Moderately proportioned, it stands two to three feet tall and 12 to 18 inches wide, a versatile bedding and border companion for midsection placements along with medium and short dahlias.

“Shines like gold”

“Glitters Like Gold” is a yellow variety available from Nature Hills Nursery in No. 1 containers.

For more information, check out our growing guide for Black Eyed Susan and our roundup of favorite varieties (coming soon!).

7. flaming star

The showy purple-pink flower spikes of the native perennial blazing star (Liatris spicata) brighten sunny gardens from late summer through fall in zones 3 to 9.

Actual heights of two to four feet and a narrow span of nine to 18 inches make it suitable for anchoring bed locations.

It also works exceptionally well when interspersed with dahlias to create a striking alternating pattern that shows off the unique shapes of each.

White flowering burning star cultivars are also available.

mixed burning star

You can find a combination of purple and white glow star bulbs available at Burpee.

Our Burning Star Growing Guide contains detailed instructions.

8. Common grass

Panic rod (Panicum virgatum) is an ornamental grass native to zones 5 to 9 that prefers full sun and tolerates partial shade.

A pink mist appears to float like a soft pastel cloud over each clump of thin blades of grass from mid-summer to fall, when it flowers and sets seeds.

The mature size is three to six feet tall and two to three feet wide.

With a spectacular combination of height, lightness and columnar shape, this companion performs best as an accent in informal galleries, with a backdrop of foreground plantings graduated in height in wide beds and a base anchor.

‘Heavy metal’

P. virgatum ‘Heavy Metal’ features blue-green foliage and reaches a mature height of three to four feet and spread of two to three feet.

You can find plants in containers n. 1 available at Nature Hills Nursery.

9. Echinacea

With daisy-like petals in shades of orange, purple, red or white, native perennial coneflowers (Echinacea spp.) are a favorite in zones 5 to 9.

In full sun to partial shade, the plants bloom from summer to fall, when the cone-shaped seed heads attract foraging songbirds.

Standard plants mature to three to four feet tall and one to three feet wide, while dwarf varieties can be six to 12 inches tall and wide.

Select by height and color to complement or contrast with dahlias in beds, borders and galleries where their compact uniformity contributes to a neat arrangement.

Warm Summer Echinacea Blend

The Warm Summer Mix features orange, yellow, red, pink, purple and cream flowers. Find 10-seed packets or a four-pack of plants available at Burpee.

Our coneflower growing guides have everything you need to get started.

10. Cosmos

A summery feel in full sun, the delicate square petals of cosmos (Cosmos spp.) can be orange, red, pink, purple, red, yellow, white or bicolor.

Annual for zones 2 to 11, reaching heights of one to six feet and widths of one to three feet, its slender stems react to the slightest breeze with a rustle of movement to draw attention to the garden.

Ranges between dahlias of matching heights for a casual cottage garden setting.

“candy strips”

‘Candystripe’ is a two-tone cultivar with two-tone pink and white petals. Seeds in 500-milligram packets are available from Botanical Interests.

Check out our guide to growing cosmos and our roundup of 25 favorite cultivars for more information.

11. Crocosmia

For full sun to partial shade, summer-flowering crocosmia (Crocosmia pottsii) is best suited to zones 6 to 9. It offers delicate orange-red, lily-like flowers on arching clusters that originate from foliage-like green foliage.

With a mature height of one to three feet and a spread of one to one and a half feet, the acutely angled leaves are impressive.

The small floating flowers look like small exotic birds, completing a bright contrast to the rose-like flowers and simple leaves of dahlias. Alternate the two in plantings for a dynamic rhythm.

‘Orange Pekoe’

You can find three-packs of “Orange Pekoe” bulbs available at Burpee.

12. Floss Flower

Lavender, pink, red, or white silkflower (Ageratum houstonianum) is a low-profile annual for zones 2 through 11 that thrives in full sun and blooms from summer to fall.

The fuzzy, button-shaped flowers create a textural contrast to the soft waxy petals of dahlias.

Mature heights range from six to 24 inches with a spread of six to 12 inches. Create a ribbon of contrasting or complementary colors in front of your gorgeous dahlias to make them stand out better.

Silk flowers ‘Blue Planet’

Pick up packets of 30 “Blue Planet” floss flower seeds from Botanical Interests.

13. Lantana

Sun-loving lantana (Lantana camara) is a perennial in zones 10 and 11 and annual elsewhere. Its multi-colored clustered flowers create a vibrant, long-lasting display from summer to fall.

A range of pinks, purples, reds and yellows makes a strident accompaniment to the rich palette of dahlias in full sun for partial shade locations.

With heights and widths of one to two feet, lantana performs well in front bed, border, and container locations.


You can find plants in gallon-sized containers available at Fast Growing Trees.

14. Pelargonium

Perennial in zones 10 to 11 and annual elsewhere, pelargonium (Pelargonium spp.), also known as scented or majestic geranium, comes in shades of pink, purple, red, white and yellow. It is a robust country house garden companion.

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