top late perennials, + smart care tips for a garden to last through fall, with kathy tracey
I HAD TO TALK MYSELF off the ledge repeatedly through the last half of July and into early August. The trigger? A garden that looked pooped and a gardener that felt the same. With the right plants and tactical tricks, though, beds and borders can carry on right through fall. Garden designer Katherine Tracey and I talked about achieving that with some tweaks now and some long-range plans and planting for coming years.
Kathy, of Avant Gardens retail and mail order nursery in Dartmouth, Massachusetts, also helps clients design and refine their landscapes, creating spaces she describes as intimate but not fussy, like her home garden. She relies on a wide palette of plants—including lots of dramatic perennials.
We talked about best practices for proactive cutbacks starting in June, and continuing now. About perennial mums to invest in (and how to care for them). About all the really tall guys of late summer—lots of sunflower relatives, and also the ironweeds or Vernonia, among others. That’sVernonia letermannii blooming above around a variegated yucca in her garden top of page.
Read along as you listen to the Aug. 6, 2018 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
late-season perennials & garden care tips,
with kathy tracey
Q. Thanks for coming to the rescue for all of us today, Kathy. How are you?
A. I’m good. I’m good. We got a little rain last night, a little. The storms keep passing us by, but I’ll take that quarter of inch.
Q. It’s interesting because we were, likewise, very dry all summer, really, and then, in the last 10 days, we’ve gotten like 3¼ inches and still coming [the show was taped July 26, 2018]. I can see the bands in the radar where it’s missing you and it’s hitting me and, whatever, every other town kind of, yes.
A. Well, you can tell that meteorologist do something to that radar because-
Q. I’m working on it. O.K.
A. It would be great to get a little bit more over here.
Q. Yes. As I said in the introduction, I mean it’s a long haul out there in the garden. Once you get past that sort of freshness and, “Oh, it’s all so new and fabulous,” of spring, it gets harder, right?
A. Well, without the rainfall, the garden gets tired. I mean there’s only so much hand-watering can do, and sprinkler systems cause their own problems with spreading mildew and diseases on plants. So a good rainfall just means the garden has a new lease on life.
Q. Yes, but even in seasons we have sort of steady precipitation, if that ever happens anymore anywhere—because I’m not clear that it does [laughter]—some stuff’s going to flop and fade and get old and tired, and we have to do some work, and we also have to have the right plants.
I don’t really know where to start in our conversation today.
Do we start in the sort of what should we have started doing when, because I know some of this we have to backtrack to tell people how they could have a garden that performs all the way through. Because some of it’s going to be retrofitting, right?
A. Sure. I mean one thing that we need to remind ourselves to get on top of is cutting back those early spring plants, plants like Symphytum. We have ‘Axminster Gold’in the garden [above, and detail in left panel of previous collage], and it offers this big, bold, gold-and-green leaf all season long, but if I don’t cut it back just about to the ground after it’s done flowering, all those flowering shoots, it really looks messy and awful. Usually, the flowers really start to fade and go the end of June, so if you can get out there and hack that plant back.
And then pay attention to give those plants a little extra water, maybe even a little fertilizer like fish emulsion, seaweed, which is what we use. Within just a very short space of time, those big, bold leaves reemerge, and they hold up well right through the summer.
Q. Right, and so yes, and it depends on, obviously, what you’ve got in your garden. And that’s kind of like a comfrey-ish looking thing, is that right, Symphytum?
A. Yes. It attracts all kinds of bees and beneficials—little blue, tubular flowers, blue fading to pink, interesting combination. There’s a solid-green form, which is equally imposing, but that gold-green leaf I especially like for its texture.
Q. Depending on what people have … and so this where I’m saying some of the tips we’re going to give today and some of the planting ideas for later, people can act on now or order stuff and buy stuff and be ready to plant and rethink some areas with some of your suggestions.
But some of this stuff started, like you said, for you and that particular plant, in late June.
For me, I have a lot of euphorbias that come early. I have a lot of perennial geraniums that kind of do their thing and finish around the first half of June, their flowering, and they’re stretched out and nasty. I’m trying to think what else that I need to really get after. Otherwise, what I end up with is sort of these floppy, weak, sometimes yellowing, nasty things, right?
Q. That’s not a good late-summer garden or fall garden, right?
A. Right, because even the new perennials that start to come to bloom, the late-summer and early fall perennials, when they come into their glory, you don’t want something tarnished-looking next door to it because it doesn’t make the best vignette. By getting on top of cutting back those geraniums and brunneras and pulmonarias, etcetera-
Q. Pulmonarias, that’s another good one. Exactly. That’s one.
A. Yes. If you don’t cut them back, they just look nasty [laughter].
Q. Yes. The other thing that this is proactive … and again, for me, because of my palette in my garden, this kind of work starts around the second week of June, and in the second half of June and all the way through July, there’s always something that needs this treatment.
The other thing that it does that’s really good is it sort of makes things a little airier, so when we do get the humid weather and, hopefully, a little rain [laughter], it’s not like slug heaven in there. Slugs love a decaying, sloppy leaf, right?
A. Sure. Yes, yes. That’s what I’ve been discovering under … and, for example, I have these big Baptisia in our garden. They’ve only been in four or five years, but they have just exceeded their bounds. What I do, just so that they don’t flop on all the neighbors around, even though the foliage of Baptisia holds up pretty well, I usually trim out some stems around the base, and so it helps hold that plant up and allow a little bit more airflow to get through to the low-lying plants that are situated nearby. [Above, left to right, Baptisia ‘Pink Lemonade’ and ‘Lunar Eclipse.’]
Q. Oh, so you kind of …
A. I do a little pruning.
Q. Right, so you’re pruning some of your perennials to allow for more room for everybody in the bed to be happier and in better shape for a longer period.
Q. Oh, good. O.K., so sort of speaking of that, and you’re talking about that’s a statuesque plant, although not as tall as some of the ones that we’re going to mention today, but things can flop not because they’re tired or that they were early spring things that are done and need a haircut, like the ones you just mentioned, but things can flop because they’re big, tall things.
I have a lot of big, big, big, tall thalictrums that just finished blooming or are blooming now, like Thalictrum rochebrunianum [above, flower detail]—I don’t even know how you say it—the really tall thalictrum, and a white one that sort of looks like that. I mean they’re like 10 feet tall.
Some of the tall composites, the daisy relatives, the sort of sunflower relatives, we get this weather, then we get winds and storms and, oof, they are flopping all over the place. What should I have been doing? You know what I mean? Because a lot of the late stuff is tall.
A. Yes, I know. If neatness is your thing, then staking them early is a good thing to do. [Laughter.] I can’t say that I’m on top of that myself, so I know exactly what you’re saying, where they just cover or billow over and maybe not in the most aesthetic way.
You can cut them back, of course, cut those back now, and they will replenish with some new foliage at the base. I know rochebrunianum does.
The tall summer-blooming Helianthus and Rudbeckia, you could prevent them from getting so tall by cutting them back maybe mid- to late spring, like early June, giving them a little clip back, which might delay flowering a little bit. But I do that with some of the aster relatives. I do that with Boltonia, which we may talk about. It’s one of the late late-summer, early fall bloomers that just adds a freshness to the garden at that time of year.
Q. Like you were saying, some of the aster relatives, some of the sunflower/composite/daisy or whatever relatives, that you give them a haircut before they’ve achieved their full stature, so in maybe early June or something, sometime around there or-
A. Right. That way, we are getting the flowers when we’re supposed to, late summer.
Q. It’s at a lower height.
A. If we were to cut them back now, we might not see too many flowers.
Q. No, no.
A. Then, of course, what’s the point?
Q. It’s at a lower overall height, so you’re like halving them around then or something? What do you do?
A. That’s why I don’t go too drastic. With the mums, the perennial chrysanthemums, I’ll go right down to 3 to 4 inches, but that’s, of course, going to bloom much later. But with plants that perhaps late July, early August blooming, and that’s when we want them to bloom, if you cut them back to maybe about a foot, 18 inches, if they’ve already exceeded that point in early mid June, then-
Q. Yes, O.K., so that’s kind of preventive. Now, you just mentioned mums, and you’re not talking about the stuff that people cart home from the garden center in the fall that’s been sheared and sheared and sheared and kept really tight, like a potted mum. You’re not talking about that. You’re talking about perennial in-the-ground plants.
A. Correct, yes.
Q. O.K., so talk about those a little bit because that’s both … there’s a tactical thing, but these are also plants that maybe people aren’t using that can bring them longevity of color in the garden if they invest in them, right?
A. Right. There’s a number of … and a lot of these are old-time varieties that just have persisted in people’s gardens, these older chrysanthemums. People have this idea that chrysanthemums should grow in little round balls like you find them at the market-
A. …at the farmstands, and at the supermarket. What they don’t realize is those pans of mums that they’re buying are multiple cuttings that were stuck in early midsummer and pinched back numerous times to get that orb-like effect.
Whereas, in the garden, if you don’t pinch back mums, they’re quite blowsy—they kind of flop and billow forth, and that can be a wonderful look. Or if you want to encourage more shoots, which means more flowers, you can shear them back. In our area I would say up until about the Fourth of July, and shearing them at like just … with your clippers or pruners. Just take them down to about 3 or 4 inches, and they regenerate with multiple new shoots, and each one of those new shoots will extend to become more flowers. It’s a good thing to do that just to encourage more flowering in the garden.
Q. Name a couple of perennial mums that you particularly like. I’m crazy about pink ones. I know that sounds crazy because it’s like, “Pink, in fall?” but I love the color pink against the fall palette of reds and fiery colors that nature provides.
A. Yes, it’s a bit of a surprise. Well, one of the most well-known, I think, is the ‘Sheffield’ [above left] or ‘Sheffield Apricot,’ or sometimes people call it ‘Sheffield Pink,’ which is a peachy-pink daisy. That one has persisted in my garden ever since I had it, so it’s not one that I’ve ever lost. Another one that I think you’ve mentioned in your podcast in previous years is that one called ‘Will’s Wonderful’ [above right], which is-
Q. Yes, it’s a crazy one. [Laughter.]
A. Yes. It blooms very late, actually. It blooms more towards the end of October into November, and it doesn’t seem to mind the colder nights that we’re getting then.
Then there’s others that have been going around. We have one called ‘October Glory,’ and the very similarly colored ‘Mary Stoker.’ A few years back, one of my gardening clients had some mums in her garden that she shared with me. They were in her grandmother’s garden.
A. Their names are not up to date. We don’t really know what they were called back then, but I just call them by what they look like. There’s a double white one that actually starts blooming in August and another one that I called Old-Fashioned Pink that really looks like it could have been a pot mum that you would buy in the fall and put in the ground to winter over. It’s a very double, and it’s a pretty shade of pink, like a dusty, warm pink.
Q. Oh, that’s funny, so you just give them names according to what they look like. That’s a good idea when one doesn’t know.
A. I acknowledge this as a made-up name on the catalog. [Laughter.]
Q. We say Plantus unknowniensis is the Latin name for that, right?
Q. For people who are like, “What are you talking about? You’re cutting back half your plant? It’s grown 18 inches, and you’re cutting it back to …”
Think about this, though–this was the time that the light bulb went off for me about shearing like that in June sometime. Sometimes that’s when I have some pests in the garden, some nuisance wildlife like woodchucks who, in my area, love the wild native violets. They also love all the native asters. And so I frequently know when the woodchuck is in the yard because my asters have been mowed to the ground in the beds, like the white wood aster, Aster divaricatus.
A. The woodchuck’s helping you with the pruning.
Q. The interesting thing is those asters still bloom, and that was, again, how the light bulb went off in my head. I was like, “Oh, wait a minute. That got eaten to the ground, but it still bloomed, and it actually bloomed at a tidier stature.”
A. You liked the results, yes?
Q. Yes. I did not like the result’s cause. [Laughter.]
A. No, no. Early on, you’re like, “Oh, no. What’s next?”
Q. Yes. O.K., so perennials mums are worth investigating, and that can give us more longevity. Tell us about some other … We were talking about tall things. I mean a number of things, I think, that you use in your garden are big stature at this time of year also. Any other big guys that we should cover?
A. Well, there’s the rudbeckias. Everybody knows ‘Goldsturm.’ It’s in all the plantings in all the supermarkets. I mean it’s a great plant. It’s very showy and looks good for a long time. There’s a few other ones, though, that people should know about. ‘Autumn Sun,’ it’s Rudbeckia nitida or laciniata [above]. The names keep changing on me, and I forget now what we should be calling it.
Q. Sometimes they use that … is it a German name or something or, I don’t know, ‘Herbstsonne?’
A. Or ‘Herbstsonne.’ Yes, yes, yes. You’ve got the accent. I don’t. [Laughter.]
Q. Yes, ‘Autumn Sun.’ I have no idea; just make up accents, it’s fine. Yes, that’s a great one.
A. Then there’s the Rudbeckia subtomentosa cultivars ‘Henry Eilers’ and ‘Little Henry.’
Q. Oh, yes.
A. That has quilled petals [above], so it’s nice as a cut flower. It blooms for a really long time starting … I’m starting to see buds on mine right now.
Q. Me, too.
A. It will carry on until September, so that’s a nice show.
Q. Do you shear that one, or do you let it go to its full extent?
A. Well, I don’t, but I should. Where I have it, it doesn’t matter too much, but if you wanted one that would be a little bit more compact, go with ‘Little Henry’ because that’s more in the 3- to 4-foot range, whereas ‘Henry Eilers’ get more of closer to 5 to 6 feet.
Q. All right, so that’s a good one. Yes, so any other kind of oddball composite-looking things that-
A. Well, it already started to bloom, but it goes on for quite a while, the cup plant, Silphium perfoliatum. It’s-
Q. Oh, yes, yes, yes. That’s a prairie native, a big, big thing.
A. Yes, with bold leaves. Then there are all the “H” plants, the Helianthus, and the heleniums, and the Helianthus ‘Lemon Queen,’ which is a perennial sunflower that spreads, so give it space if you want to try this. It’s a good back-of-the-border or a wild border plant.
Q. Is that one of the tuberous sunflowers that like … from our native Helianthus tuberosus or the Jerusalem artichoke, or is this something else? it’s a perennial but not tuberous? I don’t know that one.
A. No, it’s not a tuberous. It’s not a tuberous one.
Q. O.K. Yes. Do you grow that ‘Nally’s Lime Dots’ [above]?
A. I do. I think that’s a fun cut flower, and it’s such a surprise to see it in the garden.
Q. Tell me, what’s the genus and species? I’m drawing a blank.
A. It’s Boltonia asteroides.
Q. Right, right.
A. It’s like ‘Snowbank,’ except without the little white petals fringing the little central disc, and so what you really have is just the central disk. I believed it was named after somebody named Nally, so the-
Q. It was indeed. It was named for John Nally, who co-created Wave Hill with Marco Polo Stufano.
A. Oh, I didn’t know that.
Q. Yes, in New York City, the renowned public garden, so John-
A. I love that garden.
Q. John died 20-something years ago, and so he didn’t get, necessarily, to see the full fruition of Wave Hill, but he was instrumental in creating it. He was an artist. He was very artistic, a very special person.
A. Oh, now I’m going to think of him every time I look at ‘Nally’s Lime Dots.’
Q. Exactly. It’s a sentimental plant for a lot of people who knew him, so that’s sweet. Yes, John Nally. It’s a funny … you just said it. It’s like, if people know Boltonia, that’s like a little white daisy-ish kind of astery-looking thing but on a taller plant, right?
A. Right, and that can get quite tall if you don’t give it a shearing midsummer, early summer.
Q. Right. This one, it has the dots, but it doesn’t have the petals, so to speak.
Q. Right, yes, so it’s kind of wacky.
A. The floral arrangers love it. They just can’t get enough of it because it just adds that fun … and it’s a perennial, of course, so it’s not like an annual that you have to plant every year to get that effect from a cut flower.
Q. Right. Any others that you want to recommend?
A. Well, we talked a little bit about asters. There’s also the fall anemones. Where they’re happy, you have quite a few [laughter] because they do spread. Some people tell me they just can’t grow it, it just does not like their garden, and so they have much smaller clumps, but they’re in shades of white and pink, and they’re just so elegant in the garden. I’m glad they’re happy in my garden because they provide me with a nice show and flowers for cutting. [Above, left to right: ‘Honorine Jobert’ and ‘Pamina’ are among several late-blooming anemones Kathy grows.]
Q. Now, do you divide those and kind of … because they tend to be a little thuggish, don’t they, where they’re happy? Don’t they kind of spread?
A. Right. You have to judge and see where you want the boundary to be with them and-
Q. O.K., so you do.
A. Sometimes they’ll move away from where you really planted them.
Q. Right, exactly.
A. They moved over to their neighbor’s spot, and you have to put them back in their place if they start giving you trouble that way.
Q. Yes. Do you use the ironweeds, the vernonias? I know the big guy, but-
A. Oh, Vernonia.
A. Well, yes. Most people are familiar with Vernonia noveboracensis, the New York ironweed, the native plant.
Q. Yes, big.
A. Great butterfly plant. Big, big, can get very imposing, and that’s fine for the wild garden. But there are two forms that are very well-behaved that could make their place in a more cultivated space. One is the dwarf ironweed, Vernonia lettermannii. It grows to about 2 feet tall. It has foliage resembling Amsonia, this thread-like foliage. Then, in late August and September, it’s covered with purple flowers that are magnets for butterflies.
Q. Ah, O.K.
A. That’s one. Now there’s a new one on the scene called ‘Southern Cross,’ which was discovered by Brent Horvath, who has a perennial nursery in the Midwest. It’s not quite clear what it is a cross of but, definitely, lettermannii is in its heritage. This one is the same purple clusters of flowers at the top, but it gets a bit taller. It’s more in the 3-foot range, and I expect that it may get closer to 4 feet in a rich, moist soil. [Above, left to right, the vernonias ‘Southern Cross’ and lettermannii ‘Iron Butterfly.‘]
Q. I want to run through some more plants. I have a couple quick questions to ask you, but … so I know you love the Tricyrtis, the toad lilies [above, a variegated leaf form and a toad lily flower detail], and Lespedeza you and I both share. And I think this is a plant that’s not grown enough, the so-called bush clover, Lespedeza thunbergii [below, the big purple mound across the lawn at Margaret’s].
A. Oh, Lespedeza … right.
Q. Big, big. It dies to the ground, but it becomes this big, big thing with either purple or white flowers.
A. It comes back every year, yes.
Q. Yes, and you use the Japanese shrub mints, the Leucosceptrum, also. Do you?
A. Leucosceptrum should be better known, and maybe they are starting to get out there, but they take a little shade, which is nice. There’s the all-gold form called ‘Gold Angel.’ That does well for me in a spot where it gets late-morning sun to early afternoon. It only gets about two or three hours of strong sunlight and then diffused sunlight afterwards.
Then there is one that my friend Gary Koller gave me called ‘Mountain Madness,’ which has a variegated gold and green leaf, and that plant is a monster. [Laughter.] From a plant that was only about 12 inches in width last spring, it’s now taking up about 5 square feet in my garden right now, 5 by 5 area.
Q. Here too, dear. Here too. Yes. I think they are worth looking into, and like with the anemones that you were talking about, the fall anemones, it’s like we have to work the perimeter with our shovel and tell them where they can and can’t be. You know?
A. That’s it, and sometimes we want a plant that gets big. Sometimes we want something that’s going to take up some space. You know? That means you need fewer of them, for one thing.
A. And they bloom late, and the bees, the honeybees were all over them last October.
Q. Interesting, interesting.
A. They bloom quite late, like late September and early October.
Q. Well, these are some of the great perennials that you’re mentioning that are going to help us stretch the season. In our last just quick minute, do you rehab your pots? Because I mean you’re like the succulent queen, and you have a lot of succulent pots, but you also have other pots.
Do you kind of pull out wretched-looking stuff or stick in some new things right now to kind of make the pots look good longer, too?
A. Yes. If you, perhaps, have a planter, and you’ve used petunia or million bells, and maybe it got a little too dry on one of those hot days and you cut them back, but they never kicked back in, you can just dig out those sad little plants and tuck something in that has interest later on in the season. I mean you could use perennials. You could use heucheras, which we’ve talked about before as being great container plants because they’re going to hold up. Their foliage is going to get even more dramatic as the fall goes on.
A. As the nights get cooler, the color intensifies. So that could be one substitute.
Q. Lots of possibilities.
A. Of course, you can use chrysanthemums.
Q. Yes, yes.
A. I’d stay away from the little potted asters, only because I feel like they don’t give you much for very long. It’s like a two- to three-week stint of color. There are the tender perennials that folks forget about, and maybe they discard them because, well, they’re not hardy, but I know that, for me, Cuphea ‘David Verity,’ with its orange, red-orange flowers, continues until hard frost.
Q. That’s a good one.
more from katherine tracey
- our past interviews about succulents and more
- the Avant Gardens nursery website
- Kathy’s blog, Garden Foreplay
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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its ninth year in March 2018. 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 Aug. 6, 2018 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
(Photos, except ‘Henry Eilers,’ pink mums, ‘Herbstsonne’ and Lespedeza, by Avant Gardens, used with permission.)
(Disclosure: Katherine Tracey of Avant Gardens is a longtime friend, and an occasional sponsor of A Way to Garden.)