ONE THING that Ken Druse and I are certain about when it comes to plants: that they will often surprise you. Some grow bigger or stay smaller than the catalog promised, and some are better- or worse-behaved, or tougher or more tender than expected. Some plants that have surprised us over the years, for better or worse (including my Japanese umbrella pine, above), were the subject of a recent conversation Ken and I had.
Ken, who gardens in New Jersey, is the author and photographer behind 20 garden books, and a longtime friend who grows lots of plants that definitely surprise me. We discussed plants that in one way or another weren’t quite what we expected, as in: surprise!
Read along as you listen to the Oct. 17, 2022 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).
surprising plants, with ken druse
Margaret Roach: Hello, Ken. How are you?
Ken Druse: Hi Margaret. Well, I’m waking up.
Margaret: Good for you. Good, good. It’s a good thing to do in the morning. Yeah. Huh. So, yes. So surprise, surprise! We’ve been gardening a long time, each of us has, and it is interesting. As much as sometimes we did our homework before we acquired something…and obviously sometimes we all impulse shop and so forth and don’t do any homework-
Margaret: …that’s always a surprise then what you bring home.
Ken: It’s always is a surprise.
Margaret: Yeah, but even with homework, it’s like sometimes the plant tells you what it wants to be in your garden.
Ken: As opposed to what the catalog or, well, even some online sources. For example, I have a Taxodium which is a baldcypress, named ‘Peve Minaret’ [above, at Ken’s], and it’s supposed to be dwarf. Everything I read about it: dwarf. The best sources, including, I won’t tell you the whole name, but the conifer society, said that it grows to 6 feet in 10 years and 2-1/2 feet wide. It’s beautiful, but it’s I’d say over 12 feet high and more than…it’s like 10 feet wide. So it just shows to go you.
Margaret: Well that word dwarf is a great one to start, with because I think that’s caused a lot of people a lot of surprises. People who have bought a dwarf, fill in the blank, often a conifer, but something that’s dwarf or so labeled, and then stayed in the same garden for a long time, not moved to a new place. Or if you go to an arboretum that has a conifer collection and it’s old, the “dwarf” conifers are not so dwarf [laughter]. So it doesn’t really-
Ken: I think it’s kind of means … well, I think it means compact maybe because this tree is compact. It’s chubby.
Margaret: Right. They say it means slow-growing.
Margaret: Slower-growing than the type, than the species that it derives from. So I have my biggest… Where I learned about that dwarf wasn’t synonymous with small, was I bought two dwarf white pines, the native Pinus strobus. They were Pinus strobus ‘Nana,’ the variety, which just means I think small or dwarf, a long time ago, decades ago. Now, they’re big [laughter]. They’re 10 feet tall and 15 feet wide or whatever.
Ken: But they’re not 100 feet tall.
Margaret: Correct. So they’re nothing like Pinus strobus in the sense that that would be a giant tree. So they’re still ‘Nana,’ but they’re not small.
Ken: Well, that’s a good thing to think about. Because you said when you go to an old collection, but if you’re in the nursery and you see these little-
Margaret: Buns, right, right, right. Scones! Ooh, I’m hungry [laughter].
Ken: Ooh, a Chamaecyparis scone. I love that.
Margaret: Yeah, and it’s true. They look like they’re going to stay tight and compact like that all the time, but they don’t. We’re generalizing. Obviously there are some plants that stay very small for a very long time.
Ken: Sometimes they say miniature. Sometimes there’s an extra word.
Ken: When I looked up ‘Peve Minaret,’ it said it grows 4 inches a year. Well, I’d say 12 inches a year.
Ken: But maybe the people who introduced it hadn’t really grown it long enough.
Margaret: Well, I think that’s the thing with … So you’re talking about a bald cypress. I’ve never grown a bald cypress, first of all, and it’s probably not in everybody’s garden. This is a particular cultivar of a bald cypress. So we’re talking about something that’s not produced in the hundreds of thousands of units a year and shipped to every garden center in America probably, right?
Margaret: It’s more of a specialty item. I think when you do that, you don’t have as much data about how it’s going to perform in different regions [laughter] and different conditions.
Ken: And moisture, things like that.
Margaret: Yeah. So the information about it that I like to look on the Missouri Botanical Garden Plant Finder site, and a few other reference sites like that, and see what is generally thought to be the range and size and so forth of things, and books, but most of my books are older, and in catalogs. If they didn’t have data from a million gardens, you know what I mean?
Ken: Well, ‘Peve Minaret,’ this particular one I keep talking about, I checked when it was introduced, and it really hasn’t been around that long. So I should tell the Missouri Botanical Garden, for example, that it’s taller than they thought, because that’s one of the sources.
Margaret: Right. So something that’s not rated as a dwarf for or anything like that, but similarly that the books and the websites say it gets to 8 to 15 feet high and wide is Aesculus parviflora, one of my favorite herbaceous shrubs. [Above, in the far distance, one giant one in fall color.]
Ken: That’s like parking a school bus in your yard.
Margaret: Bottlebrush buckeye. It does. It gets to that…and then it becomes a colony, because it’s something that kind of suckers, kind of colonizes underground and expands its territory sideways. I have five of them. They’re very large plants.
Ken: Oh my gosh.
Margaret: Let’s see, one, two, three, four. No, maybe four of them. And one is 20 or more feet across, its territory now, because it’s been going a long time. So in truth, the one plant, if we could find that original stem, so to speak, the original material that was the first plant in the middle of the colony, maybe that … But now it’s this enormous, enormous group of underground connections [laughter].
Ken: Well, you have space for that giant plant. But listening to what you’re saying, I’m thinking about plants that, if you plant and you don’t have the space, become what we call invasive plants. Something that’s too lusty.
Margaret: Right, right. So, oh boy. Now you’re going to get us started on “groundcovers,” huh?
Ken: I was in a garden in Vermont, a garden of some people who are really expert. And there’s this really cute groundcover, very short, and it had little yellow flowers, and it had beautiful foliage. The owners of the garden swore that it was not invasive. It was a wonderful delicate plant. They gave me just a little bit. I will never be rid of this plant in my lifetime, ever.
Ken: Impossible. Even if you try to spray it with something like vinegar or something, the leaves are repellent [laughter].
Margaret: Yeah. That’s really why the definition of weed isn’t universal, but is wrong plant in the wrong place because, in their Vermont garden, something kept it in check, that it was an acceptable level of performance and vigor. And in your garden, it’s out of control. Is it because it’s a zone and half warmer? Is it because blah, blah, blah, blah? Who knows what, right?
Ken: Well, you said the word weed, and what came to mind was a plant that was on this property when I came here, which is goutweed. How about that one? Aegopodium.
Margaret: Yeah, that’s one that I think we all inherited. Right, right.
Ken: It’s still sold.
Margaret: Right, especially the variegated one, right?
Ken: Right, but I saw an ad for the green one recently.
Margaret: That’s insane.
Ken: If you have that, you will never ever be rid of it no matter what.
Margaret: Yeah, it’s insane. So size is one thing. So related to size and the dwarf thing being one surprise kind of thing, because the dwarf wasn’t dwarf anymore: Some things even that I planted at the same time, even that were all conifers within a couple of years of each other that I planted them, some grew so fast. The rate of growth can be so insane. Like Metasequoia, the dawn redwoods [photo by Ken, above].
Ken: Oh, for you, too? I thought it was because they reached the underground water source or something here.
Margaret: So you had the same experience. I think they’re known to be very fast-growing, and it will say that in the books.
Ken: And then they stop. They get to a certain height and then they get wide [laughter].
Margaret: But it’s like when they talk about fast, they really mean fast. Unbelievable how that tree grows. Then the other surprise about that one is that even though it’s gigantic [laughter], it has the tiniest little female cones [above]. The seed cones are the tiniest most beautiful little things. So a funny juxtaposition against such a big, mighty, fast growing, vigorous tree is these delicate little creatures.
Ken: A beautiful tree. It gets these, what, like fissures. What would you call the way that the trunk is?
Margaret: The bark, yeah.
Ken: And the deep ridges. That’s so beautiful.
Margaret: Yeah. Really wonderful. So the dawn redwood, a deciduous conifer, another distinction about it. Contrast that growth rate-wise against my oldest plant, the plant that I brought here from the garden I had made for a few years before I came here to this place probably 35 years ago. So I’d had it, I dug it out; I’d had it a few years. I dug it up and I put it in the moving van, which was a Japanese umbrella pine or Sciadopitys verticillata. That does say in the books very slow rate of growth, like 6 inches a year or less or whatever. It really is true, and it’s not until 20 or 30 years that it starts to get fuller and grows a little more rapidly or whatever. Really fleshes out.
Ken: I remember years ago that plant … well, still is: You don’t see it very often. In a way, it’s rare. I saw it on Long Island Zone 7, and I was told that it was a Zone 7 plant. It wasn’t until you told me you grew it up there in Zone 5, that it’s a hardy, hardy plant. I think that’s one reason that people don’t grow it. Also, I guess deer eat it, too. I don’t know.
Margaret: I don’t know. I have a fence, but in the years that I didn’t have a fence, I never had any deer moments with it. But it’s very close to the house and that may be why. I don’t really know.
Well, so speaking of then, you sort of mentioned hardiness. That’s another thing that, if we’re smart, we look up in the book before we purchase something, especially a tree or shrub that’s going to get big and we’re going to have a long time, and it’s going to cost a lot of money relative to say an annual. We look up not just the size, but also the hardiness. That’s another one where maybe these lesser-grown, less-popular…where there’s less information about them.
Ken: Or some salespeople who are eager to stretch the zone limits to sell the product. They sometimes warn you.
Ken: Someone we know [laughter].
Ken: Love it.
Margaret: Which is this incredible world-class collection of woody plants. Dr. Michael Dosmann, I was asking him about something about hardiness and why is it in all the books different, just what we’re talking about. He said, “Remember,” and this is sort of a quote, “not all individuals within a species are created equal.” And that provenance, where it came from, where was the mother plant that gave you the seed or whatever, really comes into play.” Particularly, he said with cold hardiness. He used the example of red maples sourced from the panhandle of Florida, where there are red maples, are far less cold hardy than those sourced from Minnesota.
Same plant genetically, but the individual … So that’s the other thing. When we’re buying a plant from the nursery, we don’t really know where it came from. They got it from a wholesaler who got it from a, who got it from a, who got it from a [laughter]. You know what I mean? Where’s the original genetics from? So that’s the other unknown factor, which I thought was really wonderful of him to remind me because I guess I kind of knew it, but I didn’t really think of it at all as one of the factors.
Ken: Yeah, I’ve read studies about the red maple.
Margaret: Yeah. So that would say that the umbrella pine also in certain parts in its range, there’s certain elevation changes in whatever. There might be some that are a little hardier than others, etc., etc. So a lot going on. A lot of possibilities that would affect the accuracy of those guesstimate [laughter] through all the books and websites.
Ken: You’re making me think of Hydrangea macrophylla, the mophead hydrangeas. They’re supposed to be hardy hear, but I never get any flowers because my season is so short. This is my theory, that the buds don’t ripen because they’re always blackened by the first killing frost. So it is hardy, but it doesn’t flower. So there’s almost no reason to have it.
Margaret: Right. So that’s another surprise, but not of the positive one, which is that you read up to see if it was hardy for you, but that didn’t mean it was going to perform.
Ken: In my own individual climate, and right here in a frost pocket because I’m in a valley. So I guess maybe I should pick plants that are for one zone colder or something. But I learned something.
Margaret: Right. I’m on a steep hillside, and that means that the warm air from below in the flatlands below me, floats up across my property in cold spells. And therefore, even though I’m higher, I’m a little … and it’s not that I’m warmer, it’s that it has good air movement, drainage, air drainage in temperature extremes. So, that’s the opposite of what you’re saying about your situation.
Ken: What are some surprises that turned out to be fabulous, like the Metasequoia… That wasn’t really a surprise, but is there anything that you purchased or tried to do and turned out to be fabulous?
Margaret: I suppose there are a lot of plants that … some that just haven’t ever missed a beat. I put a big purple copper beech up on the hill, dragged it up with two neighbors, dragged it, a ball and burlapped plant. Dragged it all the way up the hill. We dug a hole and planted it. It just has never missed a beat. It’s just this massive tree now. So sometimes you score and things go right, and sometimes things go really wrong [laughter]. [Above, its leaves just unfurling in spring.]
Ken: But we don’t see those things anymore.
Margaret: No, but the … I don’t know. Tell me one of your surprises that was fabulous surprise.
Ken: Well, I was thinking while you were talking. You know Corydalis lutea, which I think is weedy, but there’s a Corydalis here that’s Corydalis ocroleuca, and it has creamy white flowers that start blooming in May and last until November, herbaceous plant. It has done that for over like 27 years
Margaret: How. So Corydalis, for people who don’t know it, it’s in the group of plants called fumitories. It’s related to the Dicentra or the whatever they’re called now, the bleeding hearts. It’s kind of delicate little foliage, little moundy thing almost.
Margaret: Textural, like ferny foliage. Then lovely little flowers. The lutea one that you said, and I have that, which is still blooming here.
Ken: Oh, it’s everywhere.
Margaret: Still blooming here, which is yellow-flowered. The one you have you said is off-white kind of flowers?
Ken: Right. It’s funny, I’ve never seen it in any garden except here [above, at Ken’s].
Margaret: Huh, interesting.
Ken: Yeah, it’s funny how that happens, and I see the yellow one everywhere.
Margaret: Right, right. Yeah, I’m trying to think of other things that have surprised me in the sort of super-positive way. Well, one thing I guess is that, in the old days especially, I was Zone 5a and it was like, oh, you can’t grow climbing roses, because they’re just too exposed. They’re up there splayed out in the cold, and getting wind-whipped and whatever, and iced and so forth. I found out about the Canadian Explorer series of roses. Do you remember?
Ken: Oh yeah, sure.
Margaret: Yeah, yeah. So ‘William Baffin,’ this rose and it’s this kind of Pepto-Bismol or darker actually, pink and really, really intense pink. Wouldn’t have been my first choice, but don’t you know that plant’s been with me for a million years. It really was not just hardy, it was like an endurance plant.
Ken: That’s interesting. I have the same experience with the Drift series of what they call them landscape roses. They’re from Canada, too. They’re clean. The leaves don’t have any disease, they bloom their heads off.
Margaret: Same here. Right.
Ken: That’s a good tip.
Margaret: Right. So sometimes when you’re told you have to dig deeper, you have to dig deeper and you find the right one that you can. It’s a surprise because it’s such a steady performer, when in fact the reputation of roses would’ve been, oh no, no; no climbing roses for you lady, kind of thing.
Ken: Well you talked about your Aesculus. Talk about steady performers. What about your Rhododendron?
Margaret: That Rhododendron was here. I have a big Rhododendron. I don’t even remember which one it is. It’s an evergreen with purple flowers. It’s massive. The damn thing is, I don’t know, 20-something feet across and I don’t even know how tall. Certainly 12 or more feet tall, 15. Yeah, it was here when I got here and it’s twice as big as it was then. It’s a remnant of whoever was here years and years ago.
Ken: Do you have to spray it with pesticide [laughter]?
Margaret: I don’t have to do anything to it. I don’t spray anything with pesticide. So it’s a real toughie. Right, exactly.
So you talked at the beginning, you talked a little bit about things that surprised us, either that they were a little too ambitious, too lusty, too…well, let’s say invasive. I mentioned the fact that back in the day, the word groundcover seems to have turned out, surprise!, to be a euphemism for a whole bunch of invasive plants. Some of our groundcovers that they were most highly touted and still are sold in the biggest numbers I think are … well, it was the classic ivies and vincas and whatever, pachysandra.
Margaret: But also lots of others. Lots of others that were … a lot of groundcovers that turned out to be the thing that you’re never going to be able to get rid of. So, that’s tough.
Then I was surprised to learn, I don’t know, maybe six, eight, how many years ago, that one of the most popular viburnums, doublefile viburnum that had been like “the plant,” is invasive. It’s invading woods adjacent to where it lives. So it’s a very prolific seeder. I think in the Midwest and in the Northeast and so forth, it’s become an invasive. So, that’s the other thing that’s been sort of a surprise, is to find out the plants that were so highly recommended turn out to have backfired.
Ken: Right. You were talking about the groundcovers and I was thinking of the ground cover we always talk about, which is Geranium macrorrhizum [above].
Ken: Which is so well behaved and so efficient and helpful. So I guess there’s a groundcover.
Margaret: Right. So it fills the space that you need it to, but it doesn’t seed around and make a mess and become this rhizome. The rhizomes the go underground deep and be impossible to remove. It’s easy to remove them.
Ken: You can just pull it out wherever you don’t want it if that happens. It’s such a wonderful plant.
Margaret: In the last couple of minutes, what other ones for any reason of surprise … When we talked the other day, we were first talking about this together on the phone. I was saying one surprise for me has been the Japanese maples in containers and how many-
Ken: Right. “You can’t grow them in Zone 5 in containers,” the people say.
Margaret: Well, that’s what it would say in the rule book. But I do in big weatherproof pots, and I drag them into the garage in the winter, but they don’t get any care while they’re in there, and it’s just as cold in there as it is outside. It’s just not windy and icy. So, that’s one surprise that’s been great. Some of them have been in those pots… I re-pot them every few years, but 15 years. Some of them are that old. That was a good investment. So in the last minute or two, any that you want to-
Ken: Well, I grew a Clematis ‘Betty Corning,’ and I think it’s sterile because it blooms for over a month with little lavender-colored bells. It’s herbaceous, mostly herbaceous. This last winter it had a little bit of growth at the bottom. Grows up to about 4-1/2, 5 feet tall every year, year after year. I don’t do anything to it and I don’t have to deadhead it because well, it doesn’t set seed. But also it’s herbaceous, so it goes right to the ground. I just grab that and throw it out.
Even though Hydrangea paniculata is such a cliche, like ‘Pee Gee’ hydrangeas, but in the last 10 years they’ve come out with such amazing ones and some people have given me some. But that plant, I don’t have to do anything. Sometimes I cut them to 12 inches, and in two years they’re back to where they were. But they’re so easy. It’s like you could drive a truck over them, I think [laughter]. I don’t recommend that.
Margaret: Right. Then speaking of a plant where there is a lot of data, because there are a lot of them out there and have been for a long time. So that’s a plant where you’re going to be told the size of this one versus that one, versus the other cultivar.
Ken: That’s true.
Margaret: Do you know what I mean? Because they’re worked on, commonly there’s a lot of breeding going on, there’s a lot of numbers of those plants out there in a lot of regions. So I think those are ones where we have a lot more reliable information than some of these other examples [laughter] that we’ve been giving.
Ken: I didn’t know that Calycanthus was going to become one of my favorite plants, even though I have to prune one of the biggest ones. But it’s a great plant for the outer regions because you don’t have to do anything to it. It’s fragrant, and the fragrance will float 30 feet from the plant when it’s in bloom, and it blooms for a long time. That was a nice surprise. [Above, in flower at Ken’s.]
Margaret: So, that’s the sweetshrub. So, that’s a good one to end on, the sweetshrub, a beautiful native shrub.
Ken: Yep. Carolina allspice, Calycanthus floridus.
Margaret: Yeah, beautiful. So thank you for talking about some surprises. Now we can go on forever because I realize, now that we’ve gotten going, that there’s a million of them, but that’s enough for now. All right. Go propagate something or prune something or whatever [laughter]. O.K. I’ll talk to you soon.
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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 13th year in March 2022. 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 Oct. 17, 2022 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).