A Comparative Evaluation of Echinacea Cultivars

Coneflower trial in Lavin Plant Evaluation Garden 2022

Purple coneflowers at Olbrich Botanical Gardens, Madison, Wisconsin

Echinacea ‘Cheyenne Spirit’

 

Echinacea ‘Glowing Dream’

 

Echinacea KISMET™ White [‘TNECHKW’]

 

‘Cheyenne Spirit’ is a mixed-color, seed-grown cultivar. The flowers averaged 4 inches wide in shades of orange, yellow, red, and purple and bloomed from mid-June to mid-August, with sporadic rebloom to mid-October. The ray florets were predominantly drooping, although the angle was slightly variable among the different colors. Despite some variation in plant forms and sizes, the individual plants of ‘Cheyenne Spirit’ were robust, bushy, and averaged 24 inches tall and 28 inches wide. A larger plot of 12 plants was grown to increase the chances of a greater blend of possible flower colors. Introduced by Kieft Seeds (PanAmerican Seed) in 2012.

‘Glowing Dream’ was notable when it was trialed in 2013-2016, so was included in the 2019-2023 trial as a comparison. The deep watermelonpink rays paired with large orange cones were a vibrant display; rays were horizontal to slightly drooping. The 3½-inch flowers opened salmon, turned watermelon-pink, and faded to light pink. A coneflower’s fading color often detracts from the fresh flowers but in this case, the light pink remained ornamental for an extended period and complimented the new blooms. ‘Glowing Dream’ had a compact and bushy habit with purple stems to 25 inches tall and 30 inches wide. A Terra Nova Nurseries, Inc., introduction.

KISMET^® White [‘TNECHKW’] was consistently ranked one of the very best coneflowers at different stages during the growing season and in each year of the trial period. Large flowers with pure white rays and green cones were abundant during the primary bloom period in July. The flowers remained pristine longer than other white coneflowers and faded late with a yellowish cast. The well-branched, compact plants were 25 inches tall and wide. KISMET® White was comparable in appearance and performance to SOMBRERO® Blanco but featured horizontal rays.

Echinacea KISMET^™ Raspberry [‘TNECHKR’]

 

Echinacea ‘Mellow Yellows’

 

Echinacea ‘Sensation Pink’

 

Echinacea KISMET^™ Raspberry [‘TNECHKR’] The vivid magenta-pink flowers were most comparable to ‘Glowing Dream’ and ‘Sensation Pink’. Its impressive floral display was due to the striking color, large size (4 inches wide with horizontal rays), and heavy flower production. Peak bloom was in late July rather than the middle of the month like most other cultivars. The bushy plants were 24 inches tall and 28 inches wide. Deer browsing reduced flower production in 2019, and minor mite damage was noted in 2023. The KISMET® series is from Terra Nova Nurseries, Inc. too.

‘Mellow Yellows’ Like ‘Cheyenne Spirit’, this is a seed-grown cultivar with flowers in shades of yellow. A cohort of 12 plants were grown to increase the chances of a good mix of possible colors. Observed flower colors included pale yellow, lemon yellow, golden yellow, and creamy white. Flowers averaged 3½ inches wide with horizontal to drooping rays. Plant habits were generally bushy with uneven stem heights averaging 24 inches tall and wide. Natural variability between the plants was expected due to its non-clonal nature, but the color blend was pleasing in mass, regardless of stem heights. Introduced by Jelitto Perennial Seeds.

‘Sensation Pink’ Was an exceptional coneflower overall and notable for its 3-inch glowing magenta-pink flowers on dark burgundy stems. The ray florets were stubby compared to many other coneflowers and drooped slightly downward around the dark cones. The vibrant flower color held for a long time before fading to lavender-pink. Plants were bushy and uniform to 24 inches tall and 28 inches wide. ‘Sensation Pink’ is a selection from Dutch breeder Marco van Noort.

Echinacea SOMBRERO^® Flamenco Orange [‘Balsomenco’]

 

Echinacea SOMBRERO^® Blanco [‘Balsomblanc’]

 

Echinacea SOMBRERO^® Tres Amigos [‘Balsomtresgo’]

 

SOMBRERO^® Flamenco Orange [‘Balsomenco’]  The deep orange-red flowers were like SOMBRERO® Adobe Orange but with darker and broader ray florets. The 3½-inch flowers were well-shaped with slightly reflexed rays and orange cones. Flowers faded to salmon and remained attractive late into the season before turning brown as all coneflowers eventually did. Plant habits were consistently full and uniform, reaching 24 inches tall and 27 inches wide.

SOMBRERO^® Blanco [‘Balsomblanc’]  The SOMBRERO^® series from Darwin Perennials were generally strong performers with three cultivars receiving excellent ratings. This series had droopy white ray florets and green cones. The 3½-inch flowers typically opened a week or two later than many coneflowers in the trial, although they peaked in mid-July along with other coneflowers. The well-branched bushy plants were uniform to 26 inches tall and 30 inches wide.

SOMBRERO^® Tres Amigos [‘Balsomtresgo’] Where ‘Cheyenne Spirit’ is a mix of plants with different flower colors, this series features three distinctive colors as flowers age. The large 4-inch flowers opened coral, matured deep watermelon-pink, and senesced to long-lasting burgundy. As the bloom period progressed, all colors were present on a plant at the same time, which created a unique and pleasing display. Rays were mainly horizontal around orange cones. SOMBRERO^® Tres Amigos exhibited great uniformity in its bushy habit and was one of the tallest coneflowers at 27 inches tall and 30 inches wide.

Echinacea 'Big Kahuna’

Seed-grown Echinacea purpurea ‘Starlight’

 

Multiple seedlings within orignal plants

 

Leaf spotting on coneflower

The coneflowers generally had well-branched, compact habits under 30 inches tall. Inferior habits manifested as spindly forms, open crowns, lack of uniformity within a taxon, or unevenness caused by competition from vigorous seedlings crowding trial plants. The habits and plant sizes of the non-clonal selections—‘Cheyenne Spirit’, ‘Mellow Yellows’, and ‘Starlight’— were less variable than expected. Within each of these cultivar groups, plant sizes typically varied by several inches and habits were generally comparable with an occasional plant having a loose habit or reduced basal growth. However, Echinacea purpurea ‘Starlight’ averaged 48 inches tall and 42 inches wide, which was much larger than the expected 24–36-inch height. 

Most coneflowers exhibited a decline in ornamental value late in the season when a significant number of spent flowers were present. Inferior habits or reduced health from pathogens and pests or from environmental factors such as drought or excessive heat sometimes contributed to the reduced value; however, shriveled black ray florets holding onto the cones on otherwise healthy plants were more often the primary reason for decreased ornamental ratings. Special attention was paid to plant health and habit quality throughout the growing season but particularly in autumn as plants were shutting down for winter. Over the trial period, we observed that healthy plants with well-foliated or bushy basal mounds late in autumn were more likely to survive the winter than were healthy plants with few to no basal leaves. This phenomenon was observed in our earlier trials too. From our observations, this trait was not unique nor pronounced on any specific taxon. The coneflowers with greatly reduced foliage that lost one or more plants over winter included ‘Balsomemyim’, ‘Balsompocel’, ‘Balsomrosa’, ‘Blushing Meadow Mama’, ‘Canary Feathers’, ‘Chiquita’, ‘Dixie Scarlet’, Firefinch™, ‘Golden Skipper’, ‘Julia’, ‘Peacock’, ‘Rainbow Marcella’, ‘The Price is White’, ‘TNECHKIO’, ‘TNECHKY’, ‘TNECHPG’, ‘TNECHPR’, ‘Tweety’, ‘Yellow My Darling’, and ‘Yellow Passion’. 

Seedlings were a continual and escalating issue beginning in 2020. Seed dispersal was mainly in the immediate area of the parent plant(s), so most seedlings grew vigorously within an existing row of trial plants, thereby outcompeting weaker plants or filling voids where original plants had died, Seedlings that replaced original plants often went unnoticed until flowers opened. Occasionally seedlings had a similar flower color and floral form to the original cultivar, which also created confusion. Seedlings were routinely removed when discovered, and in certain cases, their removal resulted in inferior or weakened habits for the remaining plant(s). 

Disease and pest issues affecting coneflower health and habit included aster yellows, eriophyid mites, fungal leaf spot, powdery mildew, and deer browsing. Aster yellows was the most significant health issue in the trial with 13 percent of plants affected. There is no cure or treatment for aster yellows, so infected plants were completely removed when diagnosed. All coneflowers in the 2003-2008 and 2009-2012 trials were infected with aster yellows, and although it was present in most years of the 2019-2023 trial, fewer plants were affected than in the earlier trials. Damage from eriophyid mites, sometimes referred to as coneflower rosette, was observed in all years of the trial. Common symptoms are galls or witches’-brooms forming on the cones and may also include curled and/or bronzed leaves. While similar in appearance to aster yellows, mite damage is cosmetic and not a long-term health issue. Removing affected flowers eliminated the mites and improved the ornamental display as new flowers later in the season were undamaged. The percentage of plant losses from aster yellows are noted in Table 2 in the Performance Report section; taxa with mite damage in one or more years are denoted with a superscript EMD following the botanical name. See sidebar for additional information on aster yellows and eriophyid mites. 

An undefined fungal leaf spot was observed on many plants. The spotting looked like Septoria leaf spot but was not confirmed. Leaf spotting was generally low, but higher infection levels were noted occasionally. Coneflowers with severe leaf spotting in one or more years were ‘Big Kahuna’ (2022), ‘Delicious Candy’ (2022, 2023), ‘Dixie Scarlet’ (2022), ‘Fiery Meadow Mama’ (2022), and ‘Sunbird’ (2021, 2022). Powdery mildew was a minor issue on ‘Pica Bella’ and ‘The Price is White’ in 2023 only. Several plants of ‘Golden Skipper’ and ‘TNECHPG’ were infested with foliar nematodes. Deer browse damage on flowers was minimal and infrequent. Hybrid coneflower cultivars are commonly rated for USDA Hardiness Zones 4-9. Winter losses were presumed to be due to weakened vigor or poor health going into winter or from wet soil conditions during winter rather than from lack of cold hardiness. Of the 274 individual plants in the trial, 75 plants died in winter. Twenty taxa had one or more plants without robust basal growth that ultimately died in winter. While not all plants that died exhibited these conditions, the preponderance of winter-dead plants did. (see Table 2 in the Performance Report section) for information on winter losses for each taxon.

The sweetshrubs’ fall color, peaking in late October, was showy enough to be considered an ornamental feature. The display on most taxa was good, though portions of the plants retained green coloration longer than others; only ‘Edith Wilder’ achieved a fully uniform yellow display. Calycanthus floridus and ‘Michael Lindsey’ followed with near complete color change and vibrant yellow and caramel tones. ‘Burgundy Spice’, with its dark foliage, produced a muddled but somewhat interesting combination of greens, yellows, and purples. The remaining C. floridus cultivars produced a less uniform mix of greens, yellows, and browns, but their fall display was an asset, nevertheless. ‘Aphrodite’ and the C. ×raulstonii cultivars had good coloration but, due to the larger size and thus greater wind resistance of their foliage, began dropping leaves before the full color transformation. Finally, ‘Venus’ remained green much longer than other taxa and did not achieve an attractive fall color display.

Most of the sweetshrubs had somewhat asymmetrical, irregular forms that tended to improve as the plants matured. Young plants produced tall, vertical stalks above the main portion of the plant, creating an uneven habit that would fill in as shoots branched out laterally in subsequent seasons. ‘Purpureus’ displayed by far the best habit in the trial, forming a uniform mass of dense foliage. ‘Athens’ and ‘Michael Lindsey’ also had superior habits compared to other Calycanthus floridus taxa. Among the hybrids, ‘Dark Secret’ and ‘Solar Flare’ had spindly, irregular forms resulting from their overall lack of vigor while ‘Aphrodite’ and ‘Hartlage Wine’ achieved fuller habits by comparison. ‘Venus’ was unusual in that its growth habit was symmetrical but less dense, creating an airy appearance. While the sweetshrubs were never pruned to observe their natural forms, some judicious pruning of errant branches would have been beneficial to all taxa except for ‘Purpureus’, whose excellent habit had no need for improvement.

All taxa except for ‘Venus’ were observed to sucker. Calycanthus floridus, ‘Edith Wilder’, ‘Michael Lindsey’, and ROY’S DARK RED™ [‘KLMY’] exhibited the most aggressive suckering, with canes emerging several feet away and approaching the height of the main shrub, while other C. floridus cultivars suckered less vigorously. ‘Aphrodite’ and C. ×raulstonii cultivars had few suckers that only reached a few inches tall. After the sweetshrubs were removed in spring 2024, a multitude of suckers emerged from the remaining roots and stolons of various taxa, which were later chemically treated. This observation was valuable as persistent suckers will pose an issue if a gardener removes an established sweetshrub.

 

Pollinator Research 

The interest from gardeners, naturalists, and ecologists in the best plants to draw a diversity of pollinating insects to gardens and landscapes has grown significantly in recent years. The pollinator discussions center around native plants versus nonnatives and cultivars of native plants or nativars. Our trials have always noted insect visitors, especially when abundant or highly diverse but the observations have been casual rather than systematic. Commonly observed macro insects (large enough to easily assign to type) on coneflowers in our trials included bees, wasps, flies, butterflies, and skippers. While anecdotal observations are helpful, they just touch the surface of what people want to know about attracting pollinators. Focused research on pollinators has increased in the past decade or so, but more must be done on important horticultural plants, both native and nonnative, which are sometimes deemed less valuable or even detrimental to native pollinators. Significant research on pollinator visitation has been conducted at Mt. Cuba Center in Delaware and the Cincinnati Zoo and Botanical Garden in Ohio (see weblinks in References). In both studies, cultivars were observed along with wild-types. The Chicago Botanic Garden is currently developing protocols for determining the value of different native garden plants for supporting diverse pollinators, taking a holistic consideration of floral traits, including a novel approach to consider the nutritional content of native plants and cultivars. The formalized protocols will be incorporated into our evaluation process in coming years.

Aster yellows damage

Aster Yellows and Eriophyid Mites

Perhaps the most grievous disease of coneflowers is aster yellows because there is no prevention or cure—all parts of the plant are infectious and potentially harmful to other plants. Phytoplasmas— specialized organisms related to bacteria—are obligate intracellular parasites of plant phloem tissue and of the insect vectors that facilitate their plant-to-plant transmission. Aster leafhopper is a sucking insect that feeds on a variety of plants passing phytoplasmas between plants. Misshapen and chlorotic leaves, stunted stems, and disfigured flowers are common symptoms of aster yellows. Affected plants exhibit virescent floral parts such as green spoon-shaped rays and/ or rosettes of leafy growth on the cones. Once infected, phytoplasmas overwinter and multiply in the roots, resulting in a chronic situation with symptoms worsening in subsequent years. Sanitation is best as soon as symptoms appear—remove and destroy all affected plants including their roots. Aster yellows is not a soil-borne organism and needs living plants to survive.

Eriophyid damage

Coneflower rosette is caused by the eriophyid mite and the floral damage mimics some of the symptoms of aster yellows. However, the damage is only cosmetic and won’t affect the health of the plant long-term. It does reduce seed production. Mites feeding on flowers cause tufted growth or rosettes to form on the cones. The deformed flowers are unsightly and similar in appearance to aster yellows. Removal of affected flowers is sufficient to reduce the mite population and improve the ornamental display.