fighting horsetail, moving hydrangea, and more: q&a with ken druse
ANYBODY GOT an Urgent Garden Question? Apparently so, and this month’s topics range from transplanting hydrangeas, to tackling horsetail or Equisetum, to growing the stinking hellebore (Helleborus foetidus), trying Tiger Eyes sumac in a pot and much more.
Because you keep asking your questions in comments here on the website, in emails, on Facebook, and now at @awaytogarden, on Instagram, too, my friend and fellow garden writer Ken Druse keeps coming back to help me answer them.
Read along as you listen to the May 20, 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).
the may urgent garden questions q&a, with ken druse
Q. So, we’ve got quite the list. But is everything O.K. over there in New Jersey?
A. You know, it was cold and spring was late, and it wasn’t going to happen, and I was afraid it was going to happen all at once, and all it’s done is caught up. Now we’re on schedule.
Q. Right, right. We had three days of 80 something, or close to 90, or whatever. And that sort of brought it right to a little more normal-ish, sort of, ish. Ish!
A. [Laughter.] Ish.
transplanting hydrangea paniculata
Q. Yes. So, I have a question from Bonita that came in the comments on the blog. She has a Hydrangea paniculata ‘Grandiflora’—a Pee Gee hydrangea, yes? She’s had it for nine years. And so, it’s now 6-1/2 to 7 feet tall. What she wants to know, is do we think it’s possible to move this tree? It’s a tree form that has been trained to a standard. It’s just not exactly in the right spot, getting a little too big, and it’s shading out other things that are beneath it and around it, and so she’s wanting to move it. And she wants to know, can she move a paniculata hydrangea? Have you ever moved one? [Above left to right, two forms of panicle hydrangea: ‘Tardiva’ and ‘Grandiflora.’]
A. Hydrangea paniculatas have wheels.
Q. Oh they do? I didn’t know that.
Q. What’s the Latin word? The technical word for wheels?
A. [Laughter.] It’s Hydrangea transporta.
Q. Transporta. O.K., good. Never heard of that.
A. Transplanted transporta. And I’ve moved them many times. I’ve never moved a standard. And I imagine she’s got a pretty nice-size trunk at this point. But, they’re very forgiving. I would try to move it before it’s leafed out. So, she might be a little late. And she could trim it a little bit, if it’s got leaves.
But try to get as much of the soil as possible. But, they kind of shallow roots, and they move very easily; they move very well. And I’ve moved them with leaves too, I shouldn’t say that, because I just said, “Don’t do that.” But, I have done that.
Q. You have done that.
A. Then they kind of limp along, they have a little wilt, and it takes them a year to get established. But, if you move them in the late winter/early spring, it’s great.
Q. That’s the easiest of all.
A. But, I would be afraid with that trunk, to make sure that it’s big enough, and sturdy enough, and maybe has a stake. She could stake it in advance.
Q. So, it’s not unstable when it gets to its new home and top-heavy.
A. Right. She needs help. [Laughter.]
Q. Needs help. I need help, but that’s a whole other matter.
A. Yes, I’ll say.
Q. A nursery near me—a friend of mine was relocating, actually he was putting on an addition, and he had a whole bunch of paniculata hydrangeas and didn’t want to lose them, but they were right where the addition was going to be. So a local nursery came and did exactly what you said, but they were not standard, so they cut them way back. I think it was actually early fall, and they cut them way back. Boy, the next year they just grew up like crazy in their new home. He moved them to another spot and they did great, so yes. I agree.
A. And they bloom on new wood, so you can do that if you do it even in fall, then you’ll have flowers next year. I cut one back, I don’t remember exactly when, to about 12 to 18 inches, and in a year it was as big as it was before.
Q. It’s crazy, right? It’s crazy.
helleborus foetidus looking scraggly
Q. So we have another question about a different subject, a herbaceous plant, from Judy, also in the comments here. She is asking about Helleborus foetidus, the stinking hellebore. She said, “it was doing so well in my garden in the end of March and early April, and now it’s droopy and looks like it won’t make it.”
Her hellebore hybrids, you know her Oriental hybrids or Helleborus x hybridus, are doing really fantastic, but she’s wondering why is this thing kind of a mess? Have you grown this one, foetidus?
A. You know, that’s exactly what happened to me. [Laughter.] Exactly, half of them are black and dead, and half of them … Well O.K., and a third of them are looking wonderful, and then a little few of them have tons of flowers but the foliage is black. I’ve found that they’re kind of mysterious in that way, but they don’t completely disappear. I have two plants and then the next year I have four plants, but they’re not the same plants, I think. [Above, a snapshot of Ken’s foetidus this week, starting to get all nasty brown and black below.]
Q. And that’s exactly right. The late Judith Knott Tyler, who wrote a great book about hellebores, and ran a hellebore nursery and so forth, she said to me years ago: “Think of it like you think of another short-lived perennial, like columbine,” right?
It’s a true perennial but … it’s not going to stay where you put it, she said. So like Mama plants going to die off, and a foot away or 10 feet away, depending, you’re going to have the babies. You’re always going to have it in sort of the general vicinity but it’s not the exact plant.
And when Mama plant is in decline, it’s going to look like hell like this. The key is to sort of facilitate that colonization—like don’t clean up the area too fastidiously and kill off the babies, because you need to rely on them to have a continuous population.
It has a very shallow root system, she said, and it doesn’t like to have too much water, so that’s another thing that can make it look even worse in its decline than otherwise. So even planting under evergreens [where it is dry] is good.
So yes, most of the other hellebores … except sternii is another species that acts like that. So these are not ones to try to cut back like we cut back our Oriental hybrid foliage, you know? You don’t do that with the foetidus. That’ll mess it up even worse. This is just one like, again, columbine, she said. It’s going to come and go at its own whim, and you’re going to have some messy moments like that. So whatever.
tiger eyes sumac in a pot?
Q. This was an interesting one, and Elaine asked it on the blog. She said she has two Tiger Eyes sumacs, so that’s a cut-leaf staghorn sumac that has gold leaves. She has them in really large pots but, uh-oh, she never envisioned they’d get quite so big as the ones she saw on Margaret’s website [above, left and right sides of photo]. [Laughter.] And she’s like, “Uh-oh. Uh-oh.“
She’s been really happy with them in pots for two years, but is it going to catch up with her? She wants to know, can this grow in a container, or should she move them before it’s too late? Have you grown this plant?
A. I’ve killed this plant.
Q. Oh good for you.
A. I’ve killed this plant I think maybe three times, and three strikes and it’s out. It’s interesting that you say containers, I didn’t think of that.
A. It’s hardy enough to grow in a container, huh?
Q. You know who actually grows it in a pot? I believe it’s Adam Wheeler of Broken Arrow Nursery, whom we adore, and who comes and does the plant sales at my house during my Open Days. I believe it’s Adam, not his former colleague Andy Brand, but I think it was Adam who has it in a pot in his garden.
Because I have big colonies of it. I have a couple of good-size colonies where I’ve let it sucker as it’s wont to do, you know? It’s kind of a suckering, woody, irregular-shaped thing.
When we’ve done workshops together in my garden, Adam will bring up that: “By the way, if you don’t have room like this like Margaret has this big space for it, you can grow it in a pot, and it’s fun.” I don’t know how many years before you have to tip it out and root-prune it or divide it or something and put it back in the pot or several pots.
A. Well also Broken Arrow is kind of close to the coast in Connecticut. It’s so warm there.
Q. A little warmer, yes.
A. Warmer and also kind of modulated, so I don’t know whether it would be quite the same. But if I go for four times, I’m going to try it in a container because I think what happened is that I don’t have enough sun for it. You probably have yours in a lot of sun.
Q. I do have it in the sun and it seems happy there. I have one in sort of half-day shade, and it grows differently. It doesn’t sucker as much, it’s more of a tree-like thing. It’s reaching up for the light, it’s not going sideways as much. I don’t know if that’s coincidence or what.
A. But no suicide?
Q. No suicide. I’ve never lost one. I’ve killed many other plants, don’t worry Ken.
A. [Laughter.] Of course.
Q. [Laughter.] So we’re going to say to Elaine, yes, go for it. She says two years she’s had it, so it must have survived the winter wherever she is, so that’s good. She may have to tip it out like we do things that we’re confining to a pot and either divide or root-prune or whatever.
A. Well if you end up having too many, I’ll go for a fourth time.
Q. O.K., so we’ll tell Elaine your address. O.K., no problem.
A. [Laughter.] I was thinking one of yours.
rodgersia growing conditions?
Q. The other day I posted on Instagram with a picture of Rodgersia foliage, a bold, shade groundcover, but tall; it’s not hugging the ground. And someone whose name on Instagram is Gardeningonrye asked, “What type of soil? What’s the site like where your Rodgersia are planted? Wet? Dry?” [Above, Rodgersia podophylla at Margaret’s.]
This person bought some plants and put them in the shade in their garden, but it’s dry shade, they say, and the plant tag didn’t say anything about a moist site, but she or he has read since that a moist site is preferred. Have you grown this one? Now this is another plant that I love.
A. Well you know I’ve been to your garden, of course, and I didn’t see that when you posted it.
Q. Have you? I didn’t remember your being here.
A. Yes. Are you talking about Astilboides [above] or are you talking about Rodgersia?
Q. Rodgersia. I have podophylla specifically.
A. I have several Rodgersia, and I grow them in quite a moist spot, I have to say. I know they’d like more sun than they’re getting in moisture, but they are not for dry shade. No way.
Q. Well, because I’m contrarian. No.
A. They want moist, moisture-retentive.
Q. So people came, and I don’t think it was Broken Arrow, but someone from maybe the Hortus garden club in the city or some group of expert plants people came. And they saw that I have it growing under a probably 75-year-old, massive triple-trunk conifer that predates me by many years.
It’s in this very strange spot between paving and where this conifer is, and you would think bone dry because of the roots of this …. again, it’s at least 75 years old, this conifer. They were like, “How did you get that to grow there? That’s supposed to be for moist, you know?”
I think even though technically there’s a lot of root competition in this particular spot, the Rodgersia—it has like a nobby kind of rhizome, not a big fibrous root system. Do you know what I mean?
Q. My soil, because I topdress with really, really good composted mulch every year, a fine-textured composted stable bedding [photo below] that’s like a wood product that was used for cows or horses and then composted. Because of that I think that my soil is highly organic, high in organic matter, even if it’s in a technically “dry” spot like under a conifer, I still think it has enough. Because this thing is, I’ve taken 500 divisions and it’s grown for 25 years in this spot, and it’s just like a thicket. It’s real happy.
So I think it’s if not moist, I think it has to be moisture-retentive soil, like good organic, highly organic. Does that make sense?
A. Yes. Now this isn’t at the base of your hill or anything is it?
Q. It’s right by the kitchen door by that triple-trunk white cedar of some kind, next to the little cabin. It’s a very strange little spot and it is-
A. Yes, but you’ve got that big hill. I think that there is water coming down.
Q. Water comes down underground, you’re right; I think that’s right. Again, I am very good to my soil, and topdress, topdress, topdress, always adding more organic matter, so it’s not a dry soil, even if it’s a spot that would otherwise be dry in normal conditions.
So that’s what we think about Rodgersia.
pulling back the mulch to sow seeds?
Q. There were a couple of related questions having to do with mulch and fallen leaves and stuff. The first one, Ken, was from Catherine, who wrote this on the blog. She says she just put down a couple of inches—this was maybe a week or two ago, at the beginning of May—a couple of inches of mulch. You know, bulk stuff that she got.
She wanted to plant some flower seeds in the same spot. Should she pull back the mulch or put the seeds on top? What’s the mechanism? The particular seeds that she’s talking about, the packet says a quarter of an inch deep. So what do you do? Do you tease stuff back?
A. Yikes. [Laughter.] There’s so many questions I want to ask her and she’s not here.
Q. She’s not here. [Laughter.]
A. You know what’s the mulch? Is it wood? I don’t know.
Q. She says its medium. It’s not like bark chips, no. It’s a …
A. O.K., organic-y.
Q. Bought [in bulk] and delivered.
A. Well I’d pull it back, anyway. I’d completely pull it back, and if the plants take, you know if the seeds come up and then you have seedlings of good size, you could move the mulch back a little bit. But I never let mulch touch any plant. You know, touch the stem of a herbaceous plant, or the trunk of a tree. Even if it’s just an inch away, all the way around the stem, because so many things can happen.
But I would think that the seeds would have a lot of trouble getting through that mulch.
Q. Yes, I don’t think you want to put them under the mulch, I think you want to tease it. You know that this reminds me of? You know Ruth Stout? Remember Ruth Stout, “The No-Work Garden?”
A. Oh wow, yes.
Q. Ruth Stout, she was this very eccentric, bold woman in Connecticut in I don’t remember when, I want to say the 1960s maybe or something or 70s, I don’t know.
A. Or before, yes. But she lived a long time.
Q. She did. She wrote these wonderful books that are classics like “The No-Work Garden” and I forget what the others are called. She would use all her debris: leaves, old corn stalks, whatever the heck, she’d lay it down. She’d sort of sheet compost or lasagna garden, right? That was her big “aha” after years of cleaning up and then bringing back mulch onto the same bed, and then cleaning up, and the spring and fall.
You know, and she’s like, “Hey. Let stuff lie, or put it nearby and use it as mulch, all your fallen debris.” She would each year go out into the vegetable garden and just tease back a furrow-shaped space and plant her squash seeds or whatever, and it reminded me of that. So that was kind of my inspiration that yes, you need to make room. And then once the plants are up as you said, you could maybe move the mulch back a little closer, but not right against.
leave leaf mulch in place, or clean up entirely?
Q. A related question: Karen asked about her garden beds, which were mulched with shredded leaves in the fall. She was wondering should she be taking them out before she top dresses with compost or does any other sort of soil amendments in the spring? She was wondering that when she was doing the spring cleanup. Or should she put the compost on top of them and just leave them there?
What’s the protocol? Do you have a standard always what you do, or does it depend on what’s growing in the bed? How do you figure it out?
A. Well it kind of depends on the condition of the shredded leaves in a way, because if it’s shredded maple leaves and it’s all slimy and gross, I’d sort of take it away and mix it with some stuff and put it back mixed up, as opposed to putting the compost right on it, which would be kind of anaerobic, and then you’d have this layer of slime. But if it’s oak leaves, or if the leaves-
Q. Crumbly, yes.
A. … have degraded, broken down over the winter and are almost like compost, you could add the compost. I like the idea of mixing them together. What do you think about that?
Q. Yes, and for me it depends also on what’s underneath, like if it’s some tiny little, if this is super-early spring and it’s like I know that my little winter aconites are in that area and they’re going to try with their little tiny heads to poke up through that. If it’s too thick, or like you say slimy and wet-looking and a mess, I’m going to tease it off there because I know what’s underneath. So sometimes that’s what guides me is what I think is coming up under there.
There’s one other thing which is that, like the Habitat Network folks at Cornell and the Nature Conservancy, and a lot of other people like Doug Tallamy and other people who advise us about habitat-style gardening and being smarter and more caring about beneficial insects and so forth, tell us that underneath stuff like leaves is where a lot of the overwintering creatures are.
That’s their habitat in the winter; they’re under there whether its larval forms of certain moths’ caterpillars or butterflies’, or spiders, or beetles. They’re under there, so if we rake off everything, we deplete the potential future generations of beneficials. So I try to not do it everywhere, like not be too obsessive. Does that make sense?
A. Right. But what about in the vegetable garden?
Q. There I tease it back, and I wouldn’t leave slimy stuff anywhere; you’re absolutely right about that. But all I’m saying is if there’s an area where there’s no plant being hurt by it being there and it’s not all nasty and too thick and slimy, I’m going to maybe leave it, because I think someone’s sleeping down there? You know?
A. Well and why would you add compost to that area unless you felt for some reason it really needed it?
Q. Right. True. All right, so we solved that one.
Q. Suzanne had a question and this is one that I’ve only had minor—thank goodness—invasions of. It’s horsetail rush, the horsetail. She says why can’t she eradicate it? She’s “added manicure scissors to her garden tool collection and have tried cutting this thug as it emerges. Help.” What to do about horsetail? [Above, a woodland in Quebec carpeted in E. hyemale; image from Wikipedia.]
And this is a fierce opponent, so Suzanne shouldn’t feel bad. Have you had it in your garden, Ken?
A. I have it, yes.
Q. Oh, congrats.
A. There’s no such thing as had it-
A. …because if you have it, you have it. I have a sort of a clump that I haven’t completely eradicated, because for some reason it sort of stays in a clump, but every now and again, like every now and again-
Q. Boing! [Laughter.]
A. …a piece pops up, or three pieces pop up, like you know, 6, 8, 10 feet away. But here, and I’m not sure whether it’s because my soil is sandy, if I go down to the bottom with my hand and just tease it out of the ground—or you could use a tool too—it comes out pretty easily, so I don’t snip it off or cut it at all. I weed it out. Then it kind of comes back to that clump. I supposed I could try to kill that clump, but I just pull it out, you know, edit like we say.
It completely works. I do it around now, just pull it out. But I know that doesn’t work for everybody, just me.
Q. No, no. But I read one study where, well first of all I’ve read in research a number of times at different university projects or whatever, that tilling can actually make the problem worse, because it spreads the rhizomes around, because this is one where a little piece over there is going to make a new colony, you know? So tilling is actually worse. Chopping it up it actually worse.
Taking it out whole is good, and that hoeing—taking it out, like what you’re saying, but using a tool like a hoe if a have a larger infestation, to dislodge and then as you say remove big pieces, or tease them out.
But it took up to 16 repeat sessions [laughter] of that to get removal. You know what I mean? That’s how consistent you had to be, right? It wasn’t like once or twice or three times. A lot of places do say that if you keep beheading it—and this is true of a lot of tenacious weed pests—if you prevent it from feeding itself by growing above ground, if you behead, and behead, and behead, and behead, and behead, you will weaken it.
A. Oh is that what this woman’s doing, do you think?
Q. That’s what I was wondering, yes.
Q. Yes, that’s what I’m wondering. Yes, yes, yes. But it’s not, again, it’s not like once or twice. It’s like 237,000 times, I think? No. [Laughter.]
A. When I tease it out, I can be a little more clear. Let’s say there’s like three little ones coming up, so I’ll go sort of dig around below them, and when I tease it out, I’m teasing out the rhizome, too.
A. So I’m going all the way back to where I can where it starts.
Q. Well Ken I know you’re not going to believe it, but we’ve almost used up all of our time once again. What’s your project this week that you’re working on in there in the garden? Anything?
Q. Oh you’re lounging? You’re watching TV? O.K.
A. Oh my gosh, there’s so much to do.
Q. I know. I’m freaking out.
A. I’m still pulling stuff out of the basement, although sometimes we-
Q. Me, too. I still … Right. Right. All the pots.
A. We’ve had frost on Memorial Day here, but you know every year you pull stuff out. Then I have to take the stuff out of the sunroom, and I’ve already had to water some things in pots.
Q. Me, too.
A. So I’m going to get the rest of the stuff out of the basement, and really, it’s cleanup. I’ve been weeding and cleaning up, and I’ll be doing that the rest of my life.
Q. We’ll check in with you in a few weeks when you are doing that still.
prefer the podcast version of the show?
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 the May 20, 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).