SUMMER HAS just officially arrived, and with it a whole new to-do list of tasks aimed at keeping the garden going in the best possible shape all season long. We are succession-sowing vegetables, of course, as the spinach and early salads fade, and probably already pulled the pansies in favor of summer annuals in the pots.
But there’s always more to do in other parts of the garden, too.
On the list are some strategic summer pruning tasks, and a likewise strategic plan for deadheading or otherwise reducing self-sowers (like celandine poppy, Stylophorum diphyllum, above) so there’s not too much of a good thing, for instance. Plus there are perennials in need of haircuts.
My friend Ken Druse, author of 20 garden books and a longtime gardener in New Jersey, calls a lot of it not full-scale cleanup exactly, but editing. And that’s our topic today, with his help.
Read along as you listen to the June 26, 2023 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).
the start-to-summer cleanup, with ken druse
Margaret Roach: Hi, Ken. Are you ready to edit-
Ken Druse: Oh, Margaret, you’ve made such wonderful promises. Can I go now?
Margaret: O.K., bye. It’s all done. Yay.
Ken: Oh, boy.
Margaret: Oh, my goodness. Well, I call June the month of the shaggies, like it’s a dance or something, “the shaggies,” [laughter] because it’s like things spring went over the hill, right?
Ken: Spring? Well, I thought May was really long and slow, and June is like gone.
Margaret: Yeah, yeah. And things can look shaggy and need a haircut, but it’s sort of like “where to begin?” because we already did the big cleanup, and we know we have another one at the end of the season. But this is something different. Like you go say “editing,” it’s like a fine-tuning, right?
Ken: Yeah. Perhaps it’s the first or second fine-tuning of the season. It doesn’t really ever stop, but I know what you’re saying. There’s a lot of things that are happening right now that need our attention.
Margaret: Well, for instance, if you have spring blooming perennials, which a lot of people do, especially both of us are Northeastern gardeners, and it’s a popular time of the year with a lot of things that bloom earlier on and bulbs, you have a lot of stuff that’s faded, herbaceous stuff that’s faded. So that’s one layer of tidying or whatever. So maybe that’s the most familiar and the most obvious, me to start there. What are some of the things-
Ken: What do you mean by dated?
Margaret: Faded. Faded.
Margaret: Faded. Faded. Yeah.
Ken: Faded? Oh, my goodness.
Margaret: Faded. Yeah, faded. Yeah. They’re all faded, and-
Ken: Oh, yeah. Like all the daffodil foliage and all that stuff?
Margaret: Yeah, exactly, exactly. Now mine, in that case, for instance, I have big masses of Narcissus, and they are not fully withered yet on their own. So I would not clean those up. And usually for me that’s around July 4th.
Ken: Well, it depends; when they turn yellow.
Margaret: Yeah, yeah. And just on the average here, it’s around the early July period.
Ken: Well, there’s some here that have already… I guess maybe they’re the earliest ones have yellowed. But there’s one that I look at every single day, and it’s completely green, and it looks just fine. But those are restoring the bulbs. They’re making carbohydrates for that underground… We need to have that foliage green as possible.
Margaret: Right. So to intrude in the name of cosmetics would be a bad idea. Whereas don’t you have some perennials that… Like I have euphorbias, for instance, early, the polychroma types and so forth the most common of the kind of chartreuse, early spring euphorbias, those are all stretched up and done. And with a nice haircut, they’ll make like a mound again.
Ken: Yeah. Lungwort, Pulmonaria [above, at Ken’s], it blooms, and then the foliage gets kind of black at the tips and black spots. I don’t know if you’ve ever noticed that.
Margaret: Yeah, absolutely.
Ken: Because you can actually cut that way back to like two inches, and it’ll have a flush of gorgeous new growth.
Margaret: Yeah. And the perennial geraniums, for me, because I rely a lot on them. I use Geranium macrorrhizum, the big root geranium [below], as a groundcover that can take almost any situation, even dry shade, but sunny spots even, I used it in. And that kind of stretches up at bloom time in May into early June. And then the choice is right now whether to sort of really haircut it, like almost with hedge shears held down low, to really cut it way down, which will remove the spent blooms as well as tighten up the foliage again, or whether to just pick out the spent blooms, or whether to turn a blind eye [laughter].
Ken: Turn a blind eye. Right. As you’re saying that, I’m thinking that’s a really good idea. I should do that [laughter], but I don’t.
Margaret: Right, right.
Ken: That’s one plant I let alone because it does so well on its own.
Margaret: Well, and I have a couple of places where it’s kind of near and narrower. It’s along the front of a bed near and narrower spot, not super-narrow, but when it’s at its full stretched up late June height and width, it’s kind of billowing out and up too much, and it makes the space feel dwarfed. It’s out of proportion. So I sometimes do it right in the very front beds near the front path to make it feel less congested. And then it comes back nice and tight for the rest of-
Ken: Ding, ding, ding. Garden forensics. You have more sun than I do, although you probably don’t grow that in full sun. And I don’t have any full sun, but I’m thinking all this stretching and everything, and I just realized mine are growing in a wall, rock wall.
Margaret: Oh, that’s funny.
Ken: So it doesn’t elongate really. I guess it’s compact and dwarfed by not having a lot of soil and moisture. And it does fine. It’s covered with flowers, but I can just enjoy it and forget it.
Margaret: So I also grow Geranium phaeum ‘Samobor’ [foliage detail, above].
Ken: [Makes rude noise.] Uh, it’s funny how-
Margaret: Why do you make that noise when I say one of my favorite plants?
Ken: I can’t believe it’s one of your favorites. I got mine from Robin Parer, oh gosh, at least 20 years ago, and it was ‘Samobor,’ the one with the really nice zone on the leaf.
Margaret: Yeah, it’s actually S-A-M-O-B-O-R, not samovar like a coffee machine [laughter].
Ken: Oh, ‘Samobor.’
Ken: Now I know. But first year I had the black zone. The next year I had probably 20 plants almost all green. And I’ve been weeding that plant out ever since. It is a weed for me. And this year I’m going to just try to deadhead it, and only take it out when it’s in the way. But it’s everywhere. And it’s funny how that can be, how a plant can be your favorite and it can be a bane for me, although it’s not the worst, but-
Margaret: Right. And so for me, ‘Samobor’ with that chevron of dark, purple-y black on the foliage, on that typical sort of geranium foliage-
Ken: Espresso. We’re not talking about the machine, but the color is.
Margaret: [Laughter.] Right, right. Espresso, good. So for me, they’ve stayed true. I get some variation in the seedling population, but not really.
Margaret: I’ve had them probably 25 or more years, and it stayed in the same area. I haven’t had it spread around particularly far. And I love it because of that sort of purplish on the leaves. I love it as a sort of mixed groundcover mixed in with some of the purple heucheras or whatever.
But the thing is when it blooms, it pushes those flowers way, way up above the mound of the variegated foliage [above], like super-high, like knee-high, and then kind of the plant just sort of falls apart. And you have to cut the flower stalks, at least, down to get a nice flush, another mound of fresh foliage. So that’s sort of one of those “must” jobs for me, because it really looks horrible. I mean, that one, it’s not an optional one.
Ken: Maybe by doing that, you’re stopping what happened here, which is it just taking over.
Margaret: Well, because I’m basically deadheading before any seeds spread.
Ken: Right, right.
Margaret: Yes, yes. Exactly.
Ken: It has flowers all along that spike that are maybe the size of a penny, sort of, but they’re very pretty colored. I love the browns. It’s kind of a eggplant color sort of, and they’re adorable, but then they make their little fruits, and then they spill their seeds, and then they choke out their neighbor.
Margaret: Well, the common name for Geranium phaeum ‘Samobor’ is the mourning widow, like at a funeral, because she has those drooping, little dark, dark, dark, dark, dark flowers, like she’s in mourning and has her head bowed.
So, yeah, so I mean, speaking of plants that we don’t agree about, not that we don’t agree about everything, dear [laughter], we both grow certain Corydalis, and I think we have different opinions about those as well, which ones are thugs and which ones are more well-behaved. Again, in different situations, plants behave differently, which Corydalis do you grow, because that’s something else that if there’s too much or whatever, I might be tidying it up around now.
Ken: Well, almost everybody grows Corydalis lutea [above], the one with the yellow flowers. And it blooms for months, and it’s a little aggressive. It self-sows around, and I didn’t have it for years. And Lois Carswell from the Brooklyn Botanic Garden gave me a little plant, and now I have more than I would want. But I have one here that’s called Corydalis ochroleuca [below at Ken’s], and it has ivory-colored flowers, and it doesn’t bounce around like lutea.
Margaret: So interesting that that’s the case, because for me, the thug would be the one that’s… And I don’t know how you’d really pronounce it… cheilanthifolia?
Ken: Yeah, that’s a nuisance.
Margaret: That’s total thug for me. So the yellow one, lutea, I have plenty, but it’s not extreme. I always have plants, but there’s not tons of them. So it’s just funny.
Ken: And you can grab it with your hands and just pull it out.
Margaret: Absolutely. Easy, easy, easy, easy. Yeah, and I know we both have a lot of columbine. I have so much now, and it’s not like I ever planted it, that I can remember.
Ken: I went through the garden this year and just reduced it by 90 percent, because I still have too much. And a couple of ones that were beautiful or double or pink or special… I found one that has gold foliage that just appeared, and there’s one that I got from Wave Hill from seed. I think it’s called something like ‘Irish Elegance’ or something, and it has white double flowers, and it’s been in the same place now for its third year. Because they’re really short-lived; they usually don’t last more than two years. But I have cleaned up so much of that. I’d probably have a pound of seed if I let the seed happen.
Ken: You think “Oh, it’s so nice,” and then it’s out of control.
Margaret: Right. So that’s something where, even though it seems extreme, I am pulling out some plants, the whole plant, before they set seed.
Ken: Right. I’m doing that, too.
Margaret: I’m deadheading some that I really like the color-
Margaret: And I hope it’ll continue for another year or whatever in that color, in that spot or whatever. You know what I mean? So I’m using multiple tactics on the same species of plant.
Ken: Well, thinking about things that I can grow and you can’t and you can grow and I can’t, I can’t grow Verbena bonariensis. And I know it’s a hardy annual, I guess, and it’s beautiful. You’ve done… I don’t know if you’re still doing it, but that was gorgeous by the pond.
Margaret: And so each year, and that’s with a lot of these self-sowing things that are in a slightly warmer climate, they’d probably be… I don’t know what they’d be [laughter]. But, yeah, so I always have some patches of it, and it migrates slightly, unless I am careful to edit, like what we’re talking about, edit and keep it in…
For all my Angelica, same thing, Angelica gigas, the same thing. It’s tempting sometimes when you see all this bounty of a plant you love like Verbena bonariensis or like Angelica gigas to think, “Oh wow, I’ve got so many. This is so great.”
But we need to edit because we need to think of about the outlines of next year’s garden as well. If we just let it get bigger and bigger… Same with the columbines, we could end up with columbines in every crack and crevice and bed and border, right?
Ken: Right. And I really Verbascum, the mulleins [above, at Ken’s], not like the roadside one, but the ones that are like candelabra and they have lots of yellow flowers and they bloom for months. And like Angelica, if you think… Well, what I’m saying is it pops up in the path.
Margaret: Yes, yeah.
Ken: So either you have to kill it or attempt to move it. And if you get it right away when it’s first appearing, you can move it, but it’s not up to its most vigorous self because it has a long taproot. But I imagine that’s similar with Angelica. Have you ever moved plants and saved them? Of Angelica?
Margaret: Yes. And I’ve given them to people also, but I do them when they’re very young. So I don’t wait until it’s really established. I think that would be very, very hard to… I don’t think it would work to dig it out.
Ken: So that’s a biennial, and verbascums are biennial. And then there’s hardy annuals like the poppies. We can talk about them in a second, but I’m wondering do you think the Angelica sprouts the same year that it blooms and then carries a little rosette over winter? Or do you think it has to wait till next spring?
Margaret: The Angelica gigas [below]?
Ken: Yeah, yeah.
Margaret: It does not bloom on a first-year plant. No.
Ken: Right. But if you sow the seeds, or if they self-sow, do they germinate this year, same year? Or do they have to go through a winter?
Margaret: I feel like… Oh, I can’t answer that. I know I always have tiny, little plants, and I always have really big plants that are in their second year. You know what I mean?
Ken: Yeah. No, I know just what you mean. Sorry to ask you such a hard question, really.
Margaret: Yeah. Sorry. I’m trying to imagine. I’d have to actually sort of test that. But Nicotiana, that’s the other thing that I have a lot of. And-
Ken: You said you had a mat of them.
Margaret: Well, that’s the thing, is that’s something that, as you know, I mean, you know better than I do, because you propagate, you grow a lot of things from seed, it’s like dust, the seed of Nicotiana, right?
And so if you have a bunch of those in a bed for sort of your summer… I have a lot of them in between where we were talking about those geraniums, like the Geranium phaeum, which is never going to be as full after its haircut as it was earlier in the season, in the spring, pre-bloom and at bloom time. So I have things like Nicotiana that self-sow in among those and give me like this second act in summer into fall. Well, that’s fine, except like you said, sometimes every single one takes, every dust-like seed. Every single one grows.
Margaret: And I do, I have mats. Now, what do you do when you have a really successful self-sower and you don’t want to get rid of it and you want to edit it? What do you do about that?
Ken: Oh gosh, someday in my lifetime I will throw away a plant [laughter], but I haven’t done it yet really. I can hardly think of it. So I’ll move them. Some will make it. Some won’t make it. And there’s no room for any of them.
It’s just like I’ve been working with primrose, with my candelabra primrose, because we had that thing we tried them over winter, and it was so successful, but what am I going to do with a thousand primroses?
Margaret: Right, right. Well, and what-
Ken: To answer the question, I planted them, and that’s crazy. So I grew them from seed, and I prick the little seedlings out, and they had to go through a winter first before they would germinate. Then I planted them on the bank of the canal, and it’s crazy. Anyway, it’s crazy.
Margaret: So well, we should move on to some woody things, too, but before we do, I was going to say you just are reminding me, you said something like who needs a million primulas or whatever?
Hellebores: I have a couple of big beds of hellebores, of the orientalis or x hybridus types that bloom in late winter and early spring. And those are prodigious self-sowers. And so next to the mama plant, there’s going to be lots and lots and lots of-
Ken: Under her leaves. And I remember when we paid $35 a plant, and we were so excited. This was probably 20 years ago, maybe more. And then I even went through a whole thing where I stratified the seed, it went through a winter. It went through a second winter…warm, cold, wet, dry, the whole thing. And then I lifted a leaf a few years later, and they’re as thick as lawn underneath there.
Margaret: Right. So they sow themselves very like a mother hen with a lot of chicks underneath her skirt [laughter], so to speak. And so what I’m doing now at this time in my garden career, I don’t want any more hellebores. I’ve got plenty. And so when-
Ken: Especially if they’re just white or pink and less than special.
Margaret: Right. When I do cleanup and when I’m weeding and when I’m just around in the garden at any time where they are, from spring cleanup on through the whole year, if I see a bunch, I just pull the whole thing out and discard it. So some friends have asked for some, and I’ve said, “Hey, just bring an empty flat, and we’ll have some potting soil, and you can stick those little babies in a flat,” like what you’re saying, pricking off one-
Ken: I just take a shovel, and they get the whole thing [laughter]. With several plants.
Margaret: Right. So what about, I mean, there are things, woody things too that need attention now, don’t you think? I mean, for instance, spring-blooming, the lilacs: In July-ish where we live, they’ll start the process of making the buds for next year that they’re going to carry over the winter. So either you prune them from just after bloom to July, or you run the risk of diminishing the flowers for next year. At least that’s the theory, so-
Ken: Because some of them make fruits. Some of the flowerheads stay green, and then you probably can see them if you look at the lilacs, little green fruits on them just turn brown and are unsightly. So in any event, those should go, and that’s-
Margaret: Well, I do that right after they finish blooming, when the blooms fade. But I’m just saying people may not have gotten to it all, and it’s sort of like this is the last bit of that window without potentially removing flower buds for next year, which will happen later in the summer. So are you doing any other pruning, any other woody stuff now?
Ken: Well, some things, if you prune them a little late, they’ll push new growth that’ll get fried. It comes out, and then it gets burnt by the sun. So I try to get all that done.
I don’t have any of the Viburnum dilatatum anymore, which is a very popular plant because it has red berries, and we like the red berries, and so do the birds. And then that plant, which is kind of invasive, and it’s certainly an exotic, gets around. So I’m growing a couple of native and local viburnum. And I know that some people think I’m a native Nazi, but it’s that I don’t want to contribute to bad things. And then, again, I-
Margaret: Right, so, again, you’re talking about the doublefile viburnum, which has become invasive in many regions of the country? Yes.
Ken: Right. And then you and I talk about Hesperis matronalis every year. People call it phlox, of course.
Margaret: The dame’s rocket, a herbaceous plant now we’re talking about. Yes.
Ken: Right. It’s a hardy annual, I guess. Maybe it’s biennial, or short-lived perennial. And that’s everywhere, covers the roadsides, because this used to be farmland, and it’s a European farm weed. But when I see it and it’s bringing color to a little spot and it smells so good, especially at night, I leave it until it stops flowering, and then I pull the whole plant out, which I know is dangerous [laughter].
Margaret: Right, because it could sow some seed.
So just so we don’t run out of time, I just want to kind of go through the woody stuff because I know that there are, for instance, in my apples, my crabapples, even my old magnolia, which it happens in some of the spots: I get those water sprouts. And things that are grafted, like my old crabapples, down at the base I get those suckers. I think that’s the other thing, is we have to go look for certain things like, again, fruit trees and so forth. They’re going to do that, and it’s a good time to take all those off, I think, if you can get in there. My espaliered Asian pair on the back of the house [above, in need of another trim up top]–
And don’t you have some topiaries or hedges or whatever that keep pushing out more, more, more, like my espalier does?
Ken: Not like your espalier, but I do have magnolias, and they do exactly that. And I have a little topiary schnauzer [above] that is a Taxus, a yew. And really, I should prune that every two weeks. It’s a nice thing to know about Taxus: It has unlimited buds, dormant buds, and some things don’t, but you have to keep up with it.
And I have a pruned beech tree that I have to keep after because it has a shape that I like. And if I don’t keep after it, it
makes these kind of whips out that go into outer space.
And I was noticing with the climbing rose, that it makes new canes and flowers at the same time, which is kind of unusual. But I have to train those new canes to go where I want them to be, so those I don’t cut off.
Margaret: Right. So one of the other things is that sometimes you get these, especially in a beautiful variegated thing, you get one green sprout, like a reversion. And those should come out whenever they occur.
But can you give us the two-minute version of your wisteria care, your how to get wisteria to bloom thing? Because that’s always a good reminder. You’re harsh with it, aren’t you?
Ken: Well, one could say that. And it works.
Margaret: Yeah. So tell us.
Ken: Because people ask me all the time, “How can I get my wisteria to bloom?” So I prune the wisteria about every two weeks. It sends out these long, wiry stems, new growth, and I prune them back to about one or two nodes that are facing in the direction I want it to grow. And I do that every two weeks until the beginning of August.
Ken: And then I stop, and it’s in a place where I just pass by it. It’s really perfect. And they bloom. So I consider it the secret to success: harsh treatment.
Margaret: Right, right. Yeah. I’m just trying to think of any other things, if I have any other things that I’m still-
Ken: You made me think of so many things that… Poppies, and-
Margaret: Yeah. Let’s just put in a word for that. I mean, one real quick one is I love the wood poppy. It’s an Eastern native. It’s not native up in New England where I am, but that I grow it as an ornamental. It’s Stylophorum diphyllum, the wood poppy, or celandine poppy.
Ken: Or celandine poppy. Right.
Margaret: Yeah. And the thing about that is it makes so many seedlings that what we were talking about before with some of the other overly enthusiastic creatures, that’s actually my really big task this week. That’s what I’ll be doing in the garden this week, is I’ll pull out half the plants probably, and with the others I’ll pull off a lot of the very beautiful, fuzzy seedheads before they ripen fully and explode. [Above, deadheaded seedpods to discard, or share with friends.]
Ken: And explode. Right.
Margaret: So that’s a combination where I’m not just “deadheading.” And some of the plants, they yellow around now. And I don’t know why one does it and another doesn’t; it must be age of the plant, but some of them I cut to the ground. So there’s just the rosette left. So it’s kind of a mixed approach, but at any rate, that’s another one. If people are growing it, it’s a wonderful plant, but you’ve got to have a firm hand with it.
So of course, we’ve run out of time again [laughter]. When are you going to be up here to help me?
Ken: After my second surgery.
Margaret: Okay, okay. All right. Well, good. So I will talk to you soon. And thank you for making time today from your chores.
Margaret: Yes, I’ll talk to you soon.
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 14th year in March 2023. 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 June 26, 2023 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).