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Read along as you listen to the October 19, 2020 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).
Margaret Roach: And he’s laughing already, though I haven’t even finished speaking the introduction. Hello there.
Ken: Well, when you tell me what I promised, it’s like, “Uh-oh, O.K.” I can’t even remember what I promised. Hi, Margaret.
Margaret: Hi, Ken. So we should say before we get started, we’re going to have a giveaway of the “The New Shade Garden” book, which is one of your most popular topics and includes a lot of, of course, groundcovers. Because shade is often made by woody plants that need someone at their feet, right?
Ken: Well, I don’t want to… Well, I can plug the book, but it has an entire chapter on groundcovers and it has a whole page on sedges. I thought, “What’s the name of that sedge?” and I looked in the book, and there it is. And that’s pretty exciting.
Margaret: Yeah. So, last time we were speaking on the show. Of course, I guess I suppose I should ask you, did you have any frost in September?
Ken: Well, it was funny because, it was like shorts one day, long pants the next day, coat the next day, shorts the next day. [Laughter.] So, I guess there were three nights of light, very light frost and the plants looked O.K., but the car was covered with what looked like ice. So, it continues to be strange, doesn’t it?
Margaret: Very strange. And so, so dry. I know you’re not as dry as I am though you’re only a couple of hours apart, but you are, but you’ve technically had more precipitation than I have a couple of hours, few hours away, but still Northeast is dry.
Ken: I put all the hoses away, I took all the hoses out. [Laughter.]
Lamiastrum galeobdolon, yellow archangel [above], which 30 or more years ago when I planted it, it was like a coveted thing. And now it’s on the invasive list in the Northwest, and it’s invading into woodlands as the climate warms in the Northeast. And you’re starting to see it on the invasive list in new areas and so forth. And I have suddenly 40 miles of it in my garden, because it no longer stays within a reasonable range.
So, I mean, maybe we should first say what’s a groundcover and what do we want to use them for anyway? Right?
Ken: Me? O.K. I think a groundcover is a plant that increases in numbers over time, but does not run away or spread too fast. It’s usually weed-suppressing; that’s what we hope. And we have a couple of those.
And you think of a groundcover is something you can walk on, but there’s not a whole lot of plants that will tolerate being walked on besides grass lawn, but a groundcover is anything that could do what I suggested first: spread a bit and suppress weeds. And it could be 7 feet tall. It can be a big shrub. And I’ve seen that, but I guess, what do you think? Is that just about it?
Margaret: Yeah! And like what you said, we think when we hear, if you hear the phrase groundcover, you would think, oh, like turf I can walk on it, but there really ain’t no such things. I mean, there’s so few things that can tolerate that. I mean maybe creeping time in a lawn you could technically walk on, but it really almost none of them. So, yeah. And it can be any height, I completely agree.
It’s maybe a living mulch is the… Claudia West, a landscape designer of Phyto Studios, she says, “Plants are the mulch.” That’s one of her key phrases that we need to remember. And I think in a way, I have a lot of masses of groundcover, like Geranium macrorrhizum, the big root geranium.
Ken: Oh, the best.
Margaret: Yeah. And doesn’t seed around. It is rhizomatous, but the rhizomes don’t spread sideways underground. It’s kind of, like it sounds, “big root,” on the surface. So I find that easy—you can just edit, you can pull out a bunch and throw it away and so forth, but it gives you that weed suppression that you were talking about, right. It’s a living mulch. It shades the ground under the trees and shrubs helps keeps moisture and etc., etc.
But it’s not so rambunctious that it’s a troublemaker. It won’t jump out of where it was, where you intended it to be. Does that make sense?
Ken: Yes. There was one plant here 26 years ago that I guess the people before I bought this place planted, and I’m still eradicating it, and it was a groundcover this year. I think it almost ate the house, and it’s a Houttuynia?
Margaret: Oh, yeah. Houttuynia, the chameleon plant [detail below], that’s a nightmare. That’s actually one of the most popular stories on my website ever, one of the most-visited from Google searches is about “How can I kill this plant?”
Ken: And it is still sold.
Margaret: Exactly. But I didn’t think that would really do much in this situations that they’re in.
Ken: Well, you have an opportunity to do some experimentation try some horticultural white vinegar maybe, or some other quote unquote organic solutions, maybe get one of those blow torches? [Laughter.]
Margaret: Yeah, flame-weeders.
Ken: Yeah. That’s not going to help, I don’t think. I wonder-
Margaret: I don’t think they call it a blow torch.
Pinellia species. They’re almost like Jack-in-the-pulpits. And I was told, “Oh, no, there’s no problem with them.” And they even hybridized. And then they got into the compost. And that’s my future, is digging out Pinellia.
Margaret: So, and for those who are listening, really what we’re both acknowledging, and we theoretically have a lot of knowledge or some expertise or whatever. And so we’re informed, and we get information from other experts and blah, blah, blah. And yet we make mistakes. And I think that’s what we’re trying to say out loud.
And also things have changed as the climate changes. Things have changed even in the same location, and things that are listed in catalogs that say, this is good for this. Well, that may be for, again, for Georgia or for Chicago, but not the opposite. And you learnl you live and learn. And I think it’s a great time, the fall, and again, and then again, in the early spring: We’ve got to acknowledge some of the things that aren’t working, not just aesthetically, but ecologically that aren’t working and that need to be dealt with, and it’s going to make a mass, it’s going to make a big empty hole. But I want to say, let’s go ahead and do it, right? Let’s go ahead and finally face some of these things, not just let them march another mile.
Ken: Definitely. And you are doing that. And I’m wondering how can we know what will be a good groundcover that will behave? And I suppose we can look at a local public garden and see what’s happening there. We can read up whatever we can. We can look to friends.
We can think about how plants behave in their native habitats, if they’re not indigenous plants. Check something out, see if it’s something that eats a woodland or covers a hillside in China and think, “Well, maybe that’s not the plant for me.”
And think about how the plant spreads, we mentioned running. So if a plant has stolons or runners or like Lamiastrum, which is like strings, almost like a strawberry—it runs. And we realized that may not be the best choice, let’s look to something like native ginger [Asarum canadense, below at Ken’s] or something that just casually spreads. And if you buy enough plants and if you divide them, it will fill in, it’ll fill in like that Lamiastrum. And it won’t even take that long. Maybe three, third year, it’ll look pretty good.
Carex, the sedges, before. And there’s a lot of them that are appropriate to different situations that are different sizes and textures. Many of them native—the ferns, we were talking about the ostrich fern, but there’s many, many, many ferns. And in each region there’s appropriate ones for different conditions. These are some of the great plants that we need to, I think, investigate. So, yeah.
Ken: There’s the native geranium, Geranium maculatum.
Ken: Do you grow that?
Margaret: I do. And it was here when I got here. So it is a native plant in my area and it’s sows in here and there in shady areas, it doesn’t make a thick groundcover. It’s more of a… It’s a perennial, but it doesn’t make a mass like the Geranium macrorrhizum does. Yeah. So, many other, I mean, Epimedium, for instance.
Ken: I can tell you some of the plants around in my garden, I’ve got even Ajuga can be O.K., and you can mow that, too. You could probably walk on the smaller ajugas, but I liked that ‘Catlin’s Giant,’ and that’s so easy to get rid of; you just pull it up.
But we’ve talked about Brunnera here in dry shade before, which you didn’t have as much luck with as I do. I have it in the driest shade of all, and it’s just, it’s a completely weed-suppressing groundcover for me. And the Carex as you talked about, and I’m going to say something, Fargesia, do you what Fargesia is?
Margaret: It’s a clumping bamboo, yes?
Ken: You are right. It’s the only winter-hardy, cold-hardy to Zone 5 non-running bamboo. And the one I grow is about 3 feet tall and it’s very beautiful. And as you said, it’s a clump, and I’ve planted it where I have erosion issues. So, it’s a groundcover, 3 feet tall, and it’s fighting erosion. And Heuchera villosa—that’s a native plant.
Margaret: I love that plant. And that will self-sow around, so you’ll get more plants and not in a nasty way—very easy to just pick up and move. So that’s one that will give you, you can start with a couple of plants and you’ll soon have plenty, I think. You can move them around and make a nice big planting.
I think Tiarella, the foamflowers, speaking of other native things, another one that I plan to use in one of the areas that I’ve begun this eradication thing—that and some Christmas fern and some other ferns. I got a certain number of each one and I thought, “You know what? I’m going to put them in one spot, and let the little young plants grow a little bit,” so that when I’m ready to move them into the eventual cleaned-up spots, that will be good. [Below, Tiarella cordifolia.]
Ken: Your splinter nursery.
Xanthorhiza, yellowroot, which is like a sub-shrub. Polygonatum, there are native Polygonatum [Solomon’s seal], and there are ones that are not native, but in time they will fill in. And usually they’re, well, they’re between 2 feet and 4 feet, depending on which kind you get.
I’d love to say the native pachysandra can be a good groundcover, but it’s a little wimpy. It’s not like the Asian pachysandra, but I have a variegated version of the Asian pachysandra, and it’s so slow. And it’s beautiful. I don’t think it’s quite the same as the army green plastic one you can drive over [laughter], not quite. I grow some Liriope, and Microbiota—do you remember that shrub that was popular-
Microbiota decussata? Yes, yes, yes [above].
Ken: Yeah, a while back, it’s sort of low-growing, I guess it’s called Siberian cypress. It’s slow, but that’s kind of a nice one. Nepeta and lavender-if you have sun, just picture Provence. You can grow lavender as a groundcover.
Margaret: Not here. [Laughter.]
Ken: Not here, either. Too cold for you.
Margaret: A lot of people had junipers as groundcovers. And one of the ones that, as a final thought, one of the ones, there’s a cultivar of the Eastern red cedar, Juniperus virginiana, called ‘Grey Owl.’ Have you ever seen it?
Margaret: It’s not super-low, but boy, it’s a beautiful blue-silver color, ‘Grey Ghost.’ So that’s when to look for, if you want a medium height groundcover, and it derives from a native Eastern conifer. Anyway, we’re out of time. Of course, of course, of course, there’s a million more to talk about.
But let’s look for some opportunities to do some cleanup. Let’s go ahead, and sort of bite the bullet, right? And maybe replace with something better.
Ken: And no Roundup.
Margaret: And no Roundup in the process. Right? Some digging folks, lots of digging. [Laughter.] You heard it here first. All right, Ken, I’ll talk to you soon. Thank you.
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Is there a groundcover (or other ambitious plant) that you are fighting to eradicate, that is taking over too much of your garden?
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“groundcovers: out with the old, in with the natives, with ken druse” was first posted here