ANY GARDENER shopping at a local nursery or paging through perennial plant catalogs can’t help but notice there are a lot of Echinacea, or coneflowers, on the market—more every year, including in unexpected colors and some with extra-showy double flowers.

But how good are all these new cultivars as garden plants? And maybe more important, how good are they at supporting pollinators? The native plant experts at Mt. Cuba Center in Delaware have just released a report on the results of a multi-year trial of Echinacea, and their insights are our topic today.

Today’s guest, Sam Hoadley, is manager of horticultural research at Mt. Cuba Center, a longtime native plant garden and research site, where he trialed 75 different Echinacea. Before joining Mt. Cuba, Sam was lead horticulturist for Longwood Garden’s hillside garden, and he received his degree in sustainable landscape horticulture from University of Vermont.

Read along as you listen to the March 1, 2021 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on Apple Podcasts (iTunes) or Spotify or Stitcher (and browse my archive of podcasts here).

comparing the many echinacea, with sam hoadley

Margaret Roach: Hi Sam, thank you for making time.

Sam Hoadley: Hi, Margaret. Thanks for having me.

Margaret: Yes. And lucky you to have one of the great jobs in horticulture, I think. [Laughter.]

Sam: Yes—I feel very lucky. And as we both know, George Coombs did a pretty fantastic job putting this program on the map, and now it’s my turn to carry the torch and it’s very exciting to be stepping into this role.

Margaret: Yes. Well, I love the Mt. Cuba trials, and I love Mt. Cuba. I first visited there when it was founded, really, as a native plant center; that was the first time that I came. So, I mean, wow, what a place.

This is not the first time that Mt. Cuba has looked at Echinacea, is it—the coneflowers—or trialed them? So tell us the scope then and now of what’s been done.

Sam: Sure. The Echinacea trial, or at least our first one, was one of the first times we really trialed plants or a whole genus formally. There were two early trials. There was Aster and Echinacea. That first trial took place from 2007 to 2009. And I think it incorporated about 48 different species and cultivars that were available on the market at that time.

In those two initial trials, we really looked at horticultural values only. We weren’t looking at the ecological aspects of the plants as much as we have in our recent trials. So it’s been about a decade or a little bit more so since that initial Echinacea trial, and a lot more Echinacea have been on the market. So, it’s almost, not that the plant—not that the initial trial was irrelevant as soon as it came out, but a lot of those plants aren’t available anymore and there’s been a lot more plants introduced since then. So, we felt it was a good idea to revisit Echinacea as a trial, include some of those newer introductions, and also include a pollinator aspect to our report.

Margaret: Yeah. Well, so probably the most common Echinacea is Echinacea purpurea, the purple coneflower. And I read in your report that the word for Echinacea comes from the Greek word for hedgehog [laughter]. [Above, a goldfinch at a hedgehog-shaped coneflower seedhead at Mt. Cuba.]

Sam: Yes. Hedgehog and/or sea urchin. Yeah. Which I think is a perfect name. It makes a lot of sense. I mean, looking at the cone in the coneflower.

Margaret: So, it may be one of the country’s most recognizable native wildflowers, wherever anyone lives. But it’s not a widespread native, I don’t think, like it’s not native in the Northeast, where I live, or in New England. I don’t know if it’s native in Delaware. But I was looking at range maps of Echinacea purpurea, I think there’s a University of Kansas scientist, Kelly Kindscher—I’m not sure how to pronounce his name. And he has incredible range maps of all the species of Echinacea and other natives. And it’s not like it’s across the whole country, is it?

Sam: Right. A lot of the bulk of Echinacea are really kind of centralized in the central United States down through the Gulf Coast states and into the Southeastern United States. There was, one species that occurred fairly locally, but unfortunately that was only a historic occurrence. Echinacea laevigata was actually observed in parts of Pennsylvania before it was extirpated from the state.

But yeah, they’re fairly widespread, different species are obviously more localized than others. But many of them do really beautifully outside of their natural ranges into gardens in the Northeast and in the mid-Atlantic.

Margaret: And then I think the interest of them as in herbalism and other things have brought them into gardens, and in some places they’ve naturalized and so on and so forth.

Sam: Absolutely.

Margaret: But just to point out, it’s not like from coast to coast that this is a native American plant literally. I mean, it’s-

Sam: Right.

Margaret: … it does well in a lot of areas, though. And it’s become known as a very recognizable wildflower. So, not content to leave well enough alone [laughter], commercial nursery breeding programs have kept introducing more and more and more and more so-called “purple” coneflower as in Echinacea purpurea. But, oh my goodness, like they’re not even purple anymore and the centers keep looking, to me, we just said like sea urchins or whatever, but they look like someone glued a cheerleader’s pompom to the middle of the thing-

Sam: Exactly.

Margaret: … and that’s a mess [laughter]. So, tell us a little bit about that.

Sam: Sure. I mean, I think since the ’90s, there’s been a lot of breeding going on with Echinacea, and that really started, one of the major pioneers of that effort, was Dr. Jim Ault at Chicago Botanic Garden, as well as other nurseries around the Eastern United States.

But they really started to play with crossing two or more species of Echinacea. There are nine species total. And one species in particular really started to allow breeders to bring in these novel colors, like the reds and the oranges, and that was Echinacea paradoxa. It’s the only species of Echinacea that’s naturally occurring outside of the pink-to-purple spectrum. It’s actually a pure yellow flower.

So, those genetics allowed for these newer colors to start being introduced. And then, double flower forms were, I believe, first found in Europe. And now they’re, I think, one of the first ones was a pink-flowered form, and then there’s been a proliferation of those as well. There’s reds and oranges and yellows and whites. So, there’s a lot of these double or pompom flowers out there as well. And there just seems to be new colors and new breeding breakthroughs all the time, which has resulted in just a tremendous amount of new cultivars that have been introduced.

Margaret: Right. So, you evaluate—at Mt. Cuba and the Trial Gardens over several years, I think—each genus that you do, and you evaluate in a couple of primary ways, including performance as a garden plant, but also, in recent years, as you said earlier, appeal to insects. And I love, love, love the line in your report that explains that none of these man-made double flowers won the insects’ approval [laughter], did they? [Above, double ‘Butterfly Kisses.’]

Sam: No, they certainly didn’t. No.

Margaret: And that’s the case really with everything we’ve gone and doubled, isn’t it? I mean, it doesn’t have the nectar and pollen resources that the single flowers of nature have.

Sam: I think that is generally the trend. Oftentimes when there is this mutation—and there are several different mutations that can result in double flowers—but often they’re replacing a reproductive structure in the flower with a structure that’s more similar to a petal. So, that would generally mean that you’re losing some of that benefit that pollinators are looking for in that reproductive structure.

Now, it’s generally thought… and we, going into this, we thought, that’s what we’re going to see, is that we’re not going to see that many pollinators being attracted to double flowers as compared to the more wild type Echinacea purpurea and related cultivars. And that’s exactly what our data supported. There were far fewer visitations to double-flowered cultivars or pompom cultivars than there were to some of the other closer-to-wild type cultivars that we had in the trial.

Margaret: So, now, who figures that out? Do you have cameras set up, like wildlife cameras? Or is someone standing there? Or how does that work? How do you get that data?

Sam: Actually, we have this wonderful team here. It’s a volunteer group of citizen scientists called the Pollinator Watch Team. I think it’s roughly 20, maybe a few more volunteers who sign up on a daily basis when the trial is in bloom. And they’re basically observing these plants and doing simple counts of the amount of pollinators that are coming to these individual cultivars.

They’ll watch a single plant for 60 seconds and then move on to the next plant and essentially tally the visitations that they’re seeing.

In different trials… We’ve done this treatment for a few different trials, but for Echinacea, we were looking specifically at bees and wasps, and we were also doing a separate count for butterflies. So, really what this data has allowed us to see is how many insects are visiting these plants. We’re not really looking at… We’re not going farther into pollen nutrition or nectar volume or anything like that. It’s simply how attractive these plants are to pollinators.

Margaret: O.K. I mean, if people want to just even do this in their own yard, literally, and it doesn’t even have to be a native plant. If you have, for instance, the panicle hydrangeas, Hydrangea paniculata, if you have a big, puffy, double one with all the sterile florets, like ‘PeeGee,’ the paniculata ‘Grandiflora.’ And then, across the yard, you have one of the more lacecap-y ones. Again, same species of plant that those derived from, straight paniculata.

Sam: Yep.

Margaret: But you’d go and stand on a July or August day or whatever you go stand next to one for five minutes and then next to the other for five minutes. I mean, you don’t even have to open your eyes. You can just hear the buzzing at the one and not the other. Do you know what I mean?

Sam: Exactly.

Margaret: Because the insects know where they’re going to get the resources, right? [Echinacea ‘Glowing Dream,’ above.]

Sam: Exactly. And that’s our thought, is that insects aren’t going to waste their time going to a plant that’s not going to give them benefits in general.

Margaret: Do the doubles even set seed? I mean, because you were talking about pollinators, Yeah. but boy oh boy, goldfinches love seed-producing perennials like that as well. Yeah?

Sam: Absolutely. The Trial Garden was an absolute hotspot for goldfinches [laughter]. In late summer and fall, when all the coneflowers were setting seed, every morning, it was just flooded with goldfinches; it was absolutely magical. But the goldfinches, we didn’t collect formal data on them and what plants they were preferring, but it was very clear to us just anecdotally that they were going to the plants that had single flowers, that had seeds that were very readily accessible. It’s unclear… We did dissect some flowers of, especially the double flowers, to look for viable seeds. We didn’t find many, if any at all. But that doesn’t mean that it’s impossible. It is possible, I suppose, to have a very light seed set or a few seeds. But more often than not, you’re seeing the best seed set on the more wild type single cultivars.

Margaret: Right. So, if you want a lot of pollinators and you want a lot of goldfinches, you probably want to stick with the single flowers.

Sam: Exactly.

Margaret: So, and the winners are… I mean, did any of the odd-colored ones even… Were any of those even in the top? You said bringing in the genetics from another species altogether to get those sort of orangey and gold and red colors and so forth. But did any of those even place highly? And tell us a little bit about some of the performance and what was “the winners?”

Sam: Sure. So, some of the ones that had somewhat unusual colors into more of the red end of the spectrum did make it in. Echinacea ‘Santa Fe,’ and Echinacea ‘Postman’ [above] and ‘Kismet Intense Orange,’ all made the list. I think actually ‘Sombrero Hot Coral’ was in there as well. So, some of those really were great plants and it shows how far breeding has progressed.

I think some of the early initial cultivars that were the first breakthroughs into this end of the color spectrum may not have been as reliably excellent garden plants. But ‘Santa Fe’ and ‘Postman’ have proven how far this breeding has come to make these plants horticulturally superior.

I think, some of my favorites and really the one that I think is the biggest take-home message here, or one of the biggest take-home messages, was our absolute top performer, which is Echinacea purpurea ‘Pica Bella’ [below].

What’s really special about this plant is that it was also the top performer in our first trial. So, it really stood the test of time. It’s very similar to the species Echinacea purpurea, it’s a little bit more compact. The flowers have a slightly different shape, the petals are a little bit more pointed and a little more outwardly held. But it’s a really stunning plant, extremely consistent. I mean, it has, again, stood the test of time. So, that was one of my favorites. We knew early on this was going to be a great plant, just seeing it in the Trial Garden, how well it was performing.

Margaret: In the early years that this proliferation began, they caught my eye at the garden center when they first started appearing and in catalogs, just like everybody else’s, because they were so different. And I tried a few and I was so turned off, because they didn’t even come back the next year in most cases. Do you know what I mean? They were pushed too quickly to market, some of the varieties. It sounds like there are some sturdier ones even in the different colors now.

Sam: Yes. That’s really, I think, what we’re seeing. And I think breeders have put a lot of effort into making these plants longer-lived. Because I think that has been one of the biggest complaints is that there’s a lack of longevity for some of these cultivars in the garden.

Margaret: O.K. So ‘Pica Bella’ was the top performer. And wow, and so many years later, a repeat performer. So, that’s great.

Sam: Yup.

Margaret: And any others that… Which one that was the most “different” was a peak performer,  and how was it different? Do you know what I mean? Which one that had been… had human influence that looked the most different?

Sam: Sure. I think Echinacea ‘Snowcone’ [above] really fits that bill. It’s a really, really compact plant. This is actually an introduction by Brent Horvath and Intrinsic Perennials in Hebron, Illinois. It’s a really compact plant. It’s only about 2-1/2 feet tall and wide, and it just makes these absolutely perfect mounds. And the foliage, when it’s in full bloom in June and July, those green mounds are completely obscured by white flowers. It almost gives the impression of… It doesn’t scream to me Echinacea, it almost looks like a mum or something like that. It’s almost too perfect. So, it may not fit into a more naturalistic design, but for a container garden or for the front of a more formal border, something like that, this would be a great plant. And this is one that has a somewhat unknown, but complex hybrid parentage. I believe Echinacea tennesseensis is in this hybrid.

Margaret: So, one of the ones, speaking of other species, there’s Echinacea pallida, I think, and it’s different looking both in shape and in color, it’s kind of paler. What about that? You included some of these other species in your trials, I think as well, didn’t you?

Sam: Yes. We included five species that are fairly available in the marketplace. Some of them you have to look for a little bit, but they are commercially available. There are an additional four species that we did not include in the trial that aren’t generally found frequently in the market. And one of them is actually federally endangered, that’s Echinacea laevigata, so propagation and distribution of that plant is pretty limited and not as successful in gardens.

But yeah, we included Echinacea angustifolia, Echinacea pallida [below], Echinacea paradoxa, which was the yellow-flowering species, Echinacea purpurea, which a lot of our cultivars and a lot of the top performers are derived from. And then Echinacea tennesseensis, which is a really cool species. I think there’s been a lot of breeding done with that species as well, incorporating that into hybrids. This was actually an endangered plant, and recently, in 2011, it was actually delisted, thanks to some really good successful conservation efforts in its native habitats in Tennessee.

Margaret: Oh yeah. So, there were quite a number of other species evaluated. That’s great. I think you said that bees and wasps were popular visitors, is that correct?

Sam: Yes. We actually found that bees and wasps were the most frequent visitors. I think a lot of times we associate—at least I associate—Echinacea with butterflies, because they always seem to be there. But as far as the percentage of visitors, I think butterflies were only about 5 percent of the total visitations.

And that varied a little bit between cultivars, for example, Echinacea purpurea ‘Fragrant Angel,’ which was actually the best plant for attracting pollinators in our trial, had something like 14 percent butterflies, which actually propelled it to the top of the list. But most of the other cultivars, it was a very, very small percentage of their total visitation.

Margaret: O.K. But bees and wasps seem to really be taken with these plants. Yeah.

Sam: Absolutely, yes.

Margaret: Yeah. So, I don’t know if there’s any other ones you want to shout out quickly and then I just wanted to ask you what you’re on to next, because I know you’re always onto something else [laughter].

Sam: Oh yeah, absolutely.

Margaret: But maybe there’s some other points that we haven’t made about these plants, or maybe you have suggestions of how to utilize them or. I don’t know, whatever you want to throw out there and then we’ll move on to what’s going on next.

Sam: Sure. I mentioned briefly Echinacea purpurea ‘Fragrant Angel’ [above], and this was actually another plant that did beautifully in the first trial. It was our best white-flowered cultivar again. And it was really, really great and popular with pollinators.

Two cultivars that I really, really loved were Echinacea ‘Sensation Pink’ and Echinacea ‘Glowing Dream.’ They’re very similar plants. They have this really intense, glowing pink-coral color. And ‘Glowing Dream’ has some really stunning dark stems, which is pretty unique, was pretty unique, in our trial. That color is just so saturated and so different, but they’re extremely eye-catching.

As far as use in the garden, I think there’s Echinacea here for everybody. I tend to lean more on the species end of things, and cultivars that resemble species a little bit more in my home garden. But there really are, there’s such a variety here. There really is an Echinacea for everybody.

I think the biggest take-home message for gardening with them is just make sure you have really well-drained soils and full sun is best. So, that’s six or more hours of full sun a day is really ideal. Although some of the species, like Echinacea purpurea and I think Echinacea laevigata, can take a little bit more shade, but you’ll get your best flowering in full sun.

Margaret: O.K. So, in the last few minutes you dug them all out and what the heck went in? I mean, how many things are you doing and what’s next on the track? I think I read that you’re studying all the sedges, the Carex, is that one thing that you’re doing somewhere?

Sam: Yes, that’s coming up. Actually, so next year you can expect to report on smooth hydrangea, Hydrangea arborescens. When we’re looking at the exact same thing you were talking about with Hydrangea paniculata, we’re looking at the pollinator profiles of those as well. And we’re finding exactly what you’re saying is that these double or these big mophead flowers are very different from lacecap flowers as far as their ability to attract pollinators.

Carex is coming up after that. We have Vernonia in the Trial Garden, so ironweeds.

Margaret: Ooh, the ironweeds are so great

.

Sam: Yeah. I’m really excited about them. Definitely unsung heroes of the fall garden. And speaking of fall gardens, we also just planted, as a replacement for the Echinacea, our Solidago trial, which I’m also looking forward to quite a lot.

Margaret: So, the goldenrods. It’s funny, Sam, I had a naturalist here—I’ve said this on the program before once or twice over the years—but maybe three, four years ago, and we did a workshop. And I have a little meadow above my house, and I’m complaining to the workshop students. I’m saying, “Oh, well, I’m really concerned because I have this Canada goldenrod and it’s going to take over my whole little meadow and oh no, oh no.” One species, in other words.

And the naturalist, the scientist I was working with, she walked into the little meadow while I was blathering to the students [laughter] and she came back with five stems of five different plants. She laid them down on the grass and she said, “Well, actually, Margaret”—she was very polite—“Actually, Margaret, you have five species of Solidago, but you don’t have the Canada goldenrod.” [Laughter.]

Sam: Very good.

Margaret: Oops, Margaret!

Sam: There’s a ton of them and they’re not very well known. And we have many species that I think will be trialed on a horticultural level for the first time-

Margaret: Great.

Sam: … in our trials here.

Margaret: Oh, they’re such productive plants and both in flower and then in seed as well. I mean, there’s a lot going on. They provide a lot of life in the habitat and in the ecosystem. Oh, that’s great.

Sam: Absolutely.

Margaret: That’s very exciting.

Sam: Yes.

Margaret: So, are you getting ready for spring or do you have snow? Or what’s the situation there right now as we get halfway through February or so, to the second half of February?

Sam: Yeah. We’re starting to gear up. We’re doing a lot of prep work to start data collection. We’re going to start really collecting data in April on the Carex trial. And then most of the other trials, the Vernonia, Solidago and Hydrangea, will really start in May. But as soon as we do have a little bit of snow on the ground, I think a little bit more is coming tomorrow, but we’ll be out in the gardens, getting things prepped and cleaned up and ready for visitors when we open in April. Yeah, I’m excited for spring [laughter].

Margaret: Yeah. I think we’re all a little cabin feverish at the moment, especially after this crazy last year. Well, Sam Hoadley from the Trial Garden at Mt. Cuba Center in Delaware. I’m so glad to finally make your acquaintance, at least out loud. And I hope you’re going to keep me posted about what’s up and especially with those Carex. I mean, I can’t wait to hear about them. So please holler anytime, O.K.?

Sam: Absolutely. Absolutely.

(All photos from Mt. Cuba.)

more from mt. cuba

• The Echinacea trial results
• Upcoming classes, many of them virtual, on native plants and other topics

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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 11th year in March 2020. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the March 1, 2021 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes/Apple Podcasts or Spotify or Stitcher (and browse my archive of podcasts here).