moquitoes & water gardens; ants in pots or on peony buds, and more: q&a with ken druse

THE LATEST CROP of Urgent Garden Questions ranges from peonies that just didn’t bloom, to ants on peony buds and ants in flower pots, mosquitoes in water gardens, slugs in everything and more–including how to source truly local native plants. Ken Druse and I teamed up to respond to them.

Read along as you listen to the July 2, 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).

You can also browse all the past Q&A’s with Ken Druse at this link, or visit him at his website.

urgent garden questions, with ken druse



Q. Hello, Ken.

A. I was going to complain.

Q. Oh. [Laughter.]

A. Because gardeners complain all the time. And I guess we have good reason, because there’s always some calamity and some horrible thing.

Q. The weather, the weather.

A. Oh my gosh, and those peonies were standing up straight, and then it rained, and now they’re all on the ground, and I didn’t think I had to use the hoop but I should have…

Q. Yes, shoulda, coulda, woulda.

A. And the loads of bugs.

Q. Yes, it’s the truth, it’s the truth. We can always just blame the weather.

why peonies fail to bloom

Q. So yes, peonies, that was one of the things—I had actually two versions of almost the same question.

Judy asked in comments, saying that she has two peonies right next to each other that have bloomed for several years. One bloomed and the other has nothing at all; good foliage but no flowers.

Michelle said she had a new—only two years old—peony. It failed to bloom this year, but last year it did get a few blooms. She wonders, should she panic? What’s she doing wrong?

So why don’t peonies bloom when they don’t bloom? What are the factors that we need to think about?

A. I know what you’re going to say … I’m going to say something and you say, “Oh yes, Ken, that’s great…”

Q. [Laughter.]

A. [parodying Margaret] “…but I’ve found through the science department of Ithaca and Cornell, that …”

O.K., Michelle’s question I like because-

Q. Have you been having a lot of coffee today? [Laughter.]

A. [Laughter.] Stop reading my mind.

Q. All right, sorry.

A. Because Michelle’s plant may have bloomed because it got juiced up before she even planted it.

Q. Exactly, exactly.

A. So, they take quite a while to settle in, so it will in time. But, you know, the thing about peonies, and it’s really true, if you plant them too deep, they won’t bloom. And if you plant them too shallow, they won’t bloom. So you really have to plant them at a very specific depth, which in most climates is between 1 and 2 inches below the surface of the soil. But in colder clients, a little bit deeper. So I don’t know where the caller/writer, of the first question, whose name I forgot-

Q.  Judy.

A.  Judy, right.

Q.  Judy said she had the two side-by-side, and…

A. Yes, that’s weird.

Q. …that’s the puzzle. And you know, when Judy, she … I wrote her back a little quick message because it was a week or two before we were going to be taping and I thought, you know, let me try to answer. And what I asked is, I said, you know sometimes with these things … well, first of all there are always mysteries in the garden.

But second of all, sometimes you have to do a little forensics. Like I have one spot in my garden right now where I had voles, and 3 feet away I didn’t have voles. You know what I mean? They tunneled right through something, but the adjacent plant wasn’t affected. It wasn’t peonies in my case. Sometimes you have to kind of go around and look and see.

A. Margaret, sometimes?

Q. All the time you have to go around. [Laughter.]

A. All the time.

Q. So forensics, right? So we can’t do that virtually on the air from here, because we can’t see the situation.

A. Did Judy tell you where she lives?

Q. No, she didn’t say.

A. Because we did have a very tough winter, and peonies are bone-hardy, so it’s generally not that. But I’m thinking, I wonder if it got mulched over or something. Maybe the depth changed somehow.

Q. Well, right. And you just said about the soil depth, and that’s very important because it can suppress their bloom if it’s too deep. And I put fresh mulch on things each year, but what I have to be careful of with certain sensitive things is that I haven’t … that the previous mulch is degrading and working into the soil, and not disintegrating but sort of incorporating, so that they don’t end up under 6 inches, you know what I mean, after a few years.

A. I would think that peonies … I was thinking, because you said voles, and peonies are really poisonous so I would think that they’d be pretty critter-free.

Q. Yes.

A. Unless, like you said, just the soil got disturbed.

Q. I was just using that as an example because I had a lot of tunneling, and I didn’t see that there was anything exactly missing. But when the snow melted, there was stuff that had been dislodged, it was half out of the ground, that kind of thing. So it wasn’t even that they ate particular things, as much as … Right now I have a whole other colony of moles; actually it’s probably not a lot of individual animals.

A. Oh my gosh. [Laughter.]

Q. And they’re doing … and they do good work, so I don’t want to hurt them. But you know, it’s kind of chaos where they are. So some of the other things affecting bloom are—and this wouldn’t be the case in two side-by-side peonies—but the light can change. And you and I know this because we have been gardening many years, when trees grow up and whatever, suddenly there may not be as much light, and you may get more sparse flowering from that as well, I think.

ants on peony buds…

A. That’s funny that you’re mentioning peonies, because someone was in the garden this week, and was sort of saying how … just casually, how important it is to have ants on the peony buds, because the peonies won’t bloom unless they have that—implying, there’s symbiotic relationship between ants and peonies flowering, Scientist Margaret. [Laughter.]

Q. Oh, that’s what the person was saying. Oh, so the person was saying to you that that’s a fact?

A. Yes.

Q. And you said?

A. I said it wasn’t. [Laughter.]

Q. Yes. And it’s funny, I think that’s one of those Google Searches that probably gets 85 billion hits every year at peony time, when there are ants crawling on peony buds everywhere that peonies grow.

A. Right, half the people say, are the ants bad for the peony? And the other people say that you have to have ants for the peonies to bloom. Both of which are wrong. [Laughter.]

Q. Right, right, right, right. So it’s not a relationship that’s essential to the peony in order to get it to flower. And it’s not the ants’ only source of food, that nectar. It’s one of these examples, I think with the peony buds, you know how they’re sticky?

A. Mm-hmm.

Q. Isn’t it one of the examples of a plant that has what they call, extrafloral nectaries?

A. Mm-hmm.

Q. In other words, nectar sources other than inside an open flower?

A. Right.

Q. Right. So, like a lot of beans—have you ever grown yard-long beans, for instance? They have extrafloral nectaries on the stems, and there’s all kinds of crazy plants that have these things. And it’s like a place for insects to sip and enjoy. Elderberries have it, passionflowers have it. I forget other ones, those are just some that come to mind. I think there’s like 2,000 species of plants that are known to have these. So it’s just like another diner to go to, right, for the ants? [Laughter.]

A. Well, and you can see when you look at a peony bud, they’re sort of shiny.

Q. Yum, yum.

A. And if you touched it, they’d be a little sticky. You know, we can’t say this for sure, but maybe ants are helping the peonies in a way because other insects might not come.

Q. Right, right. And so, there is certainly part of a big puzzle, a big interactive puzzle. But it’s not that the peony can’t flower if an ant doesn’t take the nectar, that’s not true.

A. I guess the most important thing is don’t get the insect spray.

Q. No, no, no, no, no, no, no, no. No killing ants, I’m not into killing ants.

A. Well, depends. [Laughter.]

…and ants in flowerpots

Q. Well that leads to another question then. I think it does, if I can even remember what the question was. Yes, Leslie said:

I dumped a large ceramic pot to refresh the soil and found a million or more ants at the bottom.” I think she counted them [laughter]. “A real nest.” And she wanted to know our thoughts. She dumped to contents nearby, out back or whatever, but is there a way to prevent this? And she says it’s happened before. Is there a way to prevent ants from colonizing inside a pot, an outdoor pot?

A. I don’t think there’s a way to prevent it, but there are ways to help it not happen to a certain extent. With the ants, I mean that’s kind of tough. I try not to let any pot sit on the ground, or sit directly on the mulch or the gravel, because critters go into those pots. Sometimes worms go in there and just mess up everything. And then when you bring in these pots, if it’s a tropical plant and you want to keep it over the winter, you bring it inside and you’ve got worms inside, or the pill bugs, or the sow bugs.

Most of these insects are feeding on decayed matter, so it’s not really harming the plant that much. But it’s gross. And who wants bugs in the house?

But I’ve had that ant thing happen, and I just … you know, I’ll just go away, after you’ve disturbed them they usually take all their little pupae and then they go away. That’s been my experience. And then just put a little medium in the bottom and start over, but get that plant off the ground.

Q. You know, it’s interesting you say that, because I was at a shop buying some large pots the other day, because a girl can’t have enough Japanese maples to put in pots, so I had to get two more because I’m so crazy.

And so, I got a couple big pots, and at the checkout the person said to me, “Do you want a trivet?” And I said I didn’t; that didn’t register in my head what that meant. And it was like a ring-shaped thing with feet [above photo] that the pot would stand on. Well, a good word “trivet,” it’s hollow, it’s just a wire circle, heavy thick wire circle, and feet. Sort of like four pot feet, but connected.

A. Oh, yes.

Q. And so it wasn’t like a trivet where it was solid on top, the surface. And so the pot stands a couple of inches off the ground. And I thought, oh. So kind of what you’re saying, is get it off the ground a little bit.

A. Well, I use pot feet, and sometimes I’ll use even just a piece of slate above some stones. But as you’re mentioning this too, maybe it wouldn’t hurt to put a piece of screen in the bottom.

Q. That’s a good idea.

A. Covering the hole, before you start. But I mean, if ants find a place they want to be, they’re going to be there.

Q. Yes.

A. I think screen—I’m going to do that, I’m going to put some just cheap window screen in the bottom of the pots.

do water gardens attract mosquitoes?

Q. So we’ve gone from no flowers, to ants, to now we have a mosquito question. And this is from somebody else, Judy, a different Judy from earlier. But she says:

“I have a question about ponds. I want to build one just off our back deck, but we live in the country with the usual mosquito population, and a friend suggested that a pond would attract more mosquitoes to the deck. Should I place it elsewhere?”

And now, you know yours was one of the first garden … in Brooklyn, when you used to live in Brooklyn, it was one of the water features by a home gardener that I saw in-person, your little one that you had there. You had that little bridge, and it was in-

A. Mm-hmm.

Q. Did you find that was a mosquito thing?

A. I find quite the contrary. Although, I guess the word “attract” maybe isn’t the right word. But ponds don’t make more mosquitoes if you do the pond really well. Because one thing is, you’re going to stock it, even if it’s just goldfish. And any mosquito that tries to lay eggs there isn’t going to be very successful, because they’re going to get eaten. Also, ponds are usually deeper than mosquitoes want it, because they want shallow water.

And the other thing is, we almost always have a pump, or a fountain, or something that keeps the water moving. And if you accidentally have like a cat food tin—in the old days in Brooklyn, people used to feed cats, and they’d leave out a cat food tin and get a little water in it, like an inch of water. That’s the place the mosquito’s going to be.

Q. Right.

A. Or you know, old tires, that’s the best for mosquitoes.

Q. When I have open days, right as you walk up to the house where you sign in at Garden Conservancy Open Days tours, I have two troughs. They’re kind of large pots, large vessels, that I have water in.

A. Oh, right.


Q. Yes, so they’re above-ground. I mean, I have to empty them in the winter because the pots would crack, so I put them away. But seasonally I have them out, and the first thing that people say, it must be a good 25% of the people ask the question all day long: “Do you get a lot of mosquitoes because of those?”

Now, I also have two in-ground water gardens in the backyard, which they don’t see when they first arrive. And those have, as you say, the moving water and so forth.

And I have to say, I’ve never noticed any mosquitoes. And frogs go in these little ones just like … for me, I don’t have fish but I have frogs—and of course, dragonflies, who reproduce, are dependent on a water source to do the reproductive cycle, as with many insects. They’re big eaters of mosquitoes; they love to dine on mosquitoes. So, you know, the water also attracts mosquito-eaters, as you’re saying with the fish, right?

A. Yes, they’re kind of like traps.

Q. So the other thing is, I cover … well, I cover most of the surface of all of my water gardens, including the above-ground ones, with floating plants. So I don’t just have this slimy, algae-filled [laughter] … you know, because I shade the water so that it doesn’t get a lot of algae and be like this nasty, funky place, like that empty cat food can.

A. [Laughter.] It just came to mind.

Q. Like a sump. I mean, I don’t have it like that. It’s shaded, the water’s shaded, it reduces the algae. But I also feel like that keeps it healthy, even in the ones that don’t have a little waterfall, these troughs don’t have moving water. But I’ve never noticed mosquitoes.

A. You’ll have to put on your goggles and get your snorkel out, and take a good look. You know, my garden is on an island in a river, so people always ask about mosquitoes. And over the years, I’ve found that the most mosquitoes happen in the drought years. And when it’s rainy like this year, there are fewer mosquitoes. And to me, anecdotally speaking, I think it’s because in a drought year water will sit in little puddles, and in a wet year the water’s moving all the time. So that’s my theory as to why it’s worse.

Q. That’s your theory. Ken Druse: You heard it here first, Ken Druse’s explanation of the mosquito ebb and flows.

A. For the last couple years, there have been mosquitoes during the day and I never had them before.

Q. Oh, you have those, yes.

A. Little stripes, and they’re really tiny, and itch horribly … and I guess they’re the tiger mosquito, because they have little stripes on their thoraxes. But I never had mosquitoes during the day, and now I do.

Q. I don’t really have a big mosquito problem, even with all my water gardens. So that’s our thoughts Judy, is that it’s not about siting the pond, it’s about making it a healthy water community, little mini-community, right?

A.  It’s nice to have running water anyway, the sound is so-

Q. The sound is wonderful, yes. And again, I’m big on shading the water with floating plants so that it’s not getting all nasty and funky.

how to source locally native plants

Q. I did a recent interview with Doug Tallamy—and you know Doug Tallamy, an advocate for habitat-style gardening, let’s say. And two people afterward wrote to ask about some of the … how to source some of the native plants he recommends.

Jennifer and Kate wrote in and said you know, “O.K. but where do I find those plants, all these great plants? Where do I find the plants Doug is describing? What nurseries carry them? How can I find sources once I do the research,” as he was recommending how to research your real native plants of value for your area. And they were wondering, where’s the mother lode of the list of nurseries?

It was interesting trying to answer that question. The big lists that I found—I went right away to … Do you ever go to wildflower dot org, the Lady Bird Johnson Wildflower Center?

A. Yes, sometimes.

Q. Yes, the website.

A. I go to Connecticut ones, more local ones. But yes, keep going.

Q. No, but exactly. So my first thought was, go to the national research where they do have a plant database online, at wildflower dot org.

But their local list wasn’t up to date, and I think exactly what you just said is right, is find your state native-plant society, and they’re going to have the most relevant list, and probably the most updated list to your area.

So I found that AHS, the American Horticultural Society, had a great list of all of the state-by-state native plants societies and their websites. So you could just go there, you can get your, whether it’s Arizona Native Plant Society or whatever it is, and you can then click off to that place and you can get probably locally relevant information.

So I think really local searching, not looking for the big national database, right?

A. Right.

Q. Yes. And you know what, I did one. I don’t know if you’ve ever tried this, but I tried it; I did a Google Search for my location, “native plants Columbia County New York” or whatever I did, or “…Hudson Valley New York.” And you know, it did really well. Because I know the native-plant people within 100 miles of me, and it resulted in some very small, obscure, important projects that are going on, restoration projects that do sell plants. And I was very impressed. So Google local search might not be a bad thing in this case.

A. So the AHS, is that ahs.org?

Q. No, it’s ahsgardening dot org is where I found the lists. But I think if you just Googled American Horticultural Society and native plant societies by state, or something like that, you’re going to get that list. And it was very useful. And I kind of clicked around, and I went to a whole bunch of them, and it was good. So that’s a way to start.

A. I want to add something to what you’re saying, too.

Q. No, I’m sorry, forget about it.

A. No I have to, please.

Q. O.K.

A. So, you know there’s all these plant societies, native plant societies in in every state, and even local chapters. And there’s also botanical gardens, sometimes they’re preserves, and they all have fundraiser sales-

Q. That’s a good point.

A. ..where members come, and everybody’s divided up stuff, like trillium or something, they bring in their plants. So if you can connect with one of those places, look at their schedules—usually the sales are in May, in the spring, sometimes two a year, sometimes there’s one in the fall. So I would say that’s a good way to get some plants, too.

Q. Yes, I think you’re right. So being local, at least at the state level, or even more hyper-local than that—your Audubon center, or your bird sanctuary, your native plant garden in your area—really look there and find out and ask there.

A. Yes, maybe join, too.

slug control

Q. We have a question about, dare I say, slugs?

A. You did.

Q. This is from Brid, like in Bridgette. She said:

“Don’t know if you can help, but I have a problem with slugs attacking my cabbage and kale leaves. Is there any organic treatment I could use?”

A. Garlic and olive oil.

Q. [Laughter.] You’re going to have delicious snails.

A. Escargot.

Q. Yes, gross.

A. Ick.

Q. Ick is right. So, what do you … what’s your … I don’t have a slug problem, but you tell me.

A. I have a snail problem.

Q. O.K.

A. I don’t have so much of a slug problem, although in Brooklyn I really did. And I have some slugs, and I think we’ve talked about it before with a couple of different insects, but if you put an old board down, I’m not kidding. Just put an old board down over night, go out in the morning, and it’s covered with slugs on the bottom. And then you have to deal with them.

If you talk to the person who made the pond, you can just give them to her for her fish, but otherwise you have to dispatch them in some way.

Q. Yes.

A. But there are some semi-organic, and I was just thinking today because there used to be slug bait that, you know, don’t let your children, or your dogs, or your pets near this stuff. It really was deadly stuff. But now the same companies, the big companies, are doing something that’s quite a bit like Sluggo. I looked at one today and it was just sulfur, and some kind of bait.

I think that the Sluggo is iron sulfate [correction: in Sluggo, it’s iron phosphate], and I’ve heard it’s not the greatest thing to use, it’s not completely organic because it can do something, but it doesn’t harm the plants apparently. And it does help. It’s not as good as the horribly deadly poison. Have you ever used anything like diatomaceous earth around vegetables, or anything like that?

Q. I have not. As I said, I don’t really have a big slug problem. I find that good garden sanitation, like reducing any kind of floppy, slightly yellowing leaves near the bottom of things to keep the air circulation good. I use a fine-textured mulch, a composted stable bedding. The mulch I think, the texture is probably not so attractive to them, it’s a little … it’s not smooth.

So, I try to keep up with the going around and grooming, grooming, grooming, taking out anything that’s kind of looking delicious, because they go for the stuff that’s decaying first normally, or down below.

You said boards in the garden. You know, I always read about how we’re supposed to put carpet samples, you know those pieces, like the 1-by-1-foot sort of carpet, that those are great.

A. That’s really gross. [Laughter.]

Q. It’s really gross, but apparently it’s really great for catching slugs. You put it down for a few nights—you wet it, you have to soak it first then you put it down for a few nights. And yes, apparently it really works well.

You know, we’ve almost run out of time again, Ken. So slugs, we’re saying trapping is the sort of non-toxic way, trapping overnight.

A. Yes, and you can use some of those less-toxic, practically not-toxic, things that don’t work as well, like Sluggo and the other bait ones. Sulfur and iron phosphate.

Q. Yes.

A. But that’s pretty cool, every silver lining has a cloud, that’s the gardener’s motto.

Q. All right, that’s Ken’s motto. Ken Druse of kendruse dot com, boy that’s his motto: perky, perky.

A. Right.

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 July 2, 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).

  1. Jennifer T Pierce says:

    Regarding slugs: Raccoons eat slugs. Since I have raccoons living in my yard now I no longer have slugs or at least to the point they do damage to my plants unless they are in pots. I see the raccoons going through the Hostas at night eating away. The raccoons do no damage to the plant itself. Of course, raccoons pose their own set of problems but so far we tolerate each other.

  2. Ann says:

    Local sourcing is ideal if you can manage it!

    Here in Maine, Maine Audubon has a Native Plant Sale at their Falmouth headquarters every June as part of the BNH program (Bringing Nature Home).
    Dr Tallamy who has come to Maine Audubon twice to speak, gave Maine Audubon permission to use the name.

    Another Maine organization, The Wild Seed Project, sells locally sourced seeds. They also publish a quarterly magazine and hold talks, wildflower walks, and workshops to educate folks on how to grow native plants from seeds (and why local sourcing is so important).

    Also the New England Wildflower Society sells native plants at Garden In the Woods, all carefully sourced and grown from seed.

  3. dana jenkins says:

    thanks for all you’ve taught me. I am an obsessed late arrivee to the gardening world. What you know and share is so helpful to me as I also am in 5b (maine midcoast). we leave for 3-4 months over the winter and I am wondering what I can keep over in pots under the porch overhang. I’m happy to cover the pots with plastic/mulch/hay or a combination of any and all but they won’t get water or much light. I want to winter over boxwood, hydrangea, and some roses in pots. Can you say more about what you keep in pots during our long, dark days and how you keep them? thanks very much,

  4. Pola says:

    Amazing interview! Kenneth is one of my biggest inspirations if it goes to gardening. I have read some of his books when I was starting my adventure with this subject. Firstly I can remember ‘Making more plants’ which made a big impression on me, and then ‘The passiong of gardening’… Still I have those books in my collection and I am hunting for some new! If it goes to peonies I love them, but once I had a problem with them that Kenneth mentioned in this interview. I planted them too deep and they hadn’t bloomed. Then, I worked out what depth is appropiate and they flourish very well every year!
    PS in website form I put link to plants I use to avoid mosquitoes!

  5. Trina says:

    I’m driving around catching up on the podcast, and just wanted to let you know how much joy I get from every episode. As a lifelong gardener it’s always fun to know I will probably learn something new, as well as just enjoying the conversations. Extrafloral nectaries, so cool!
    Thanks for sharing!

  6. Pola says:

    Amazing interview! Kenneth is one of my biggest inspirations if it goes to gardening. I have read some of his books when I was starting my adventure with this subject. Firstly I can remember ‘Making more plants’ which made a big impression on me, and then ‘The passiong of gardening’… Still I have those books in my collection and I am hunting for some new! If it goes to peonies I love them, but once I had a problem with them that Kenneth mentioned in this interview. I planted them too deep and they hadn’t bloomed. Then, I worked out what depth is appropiate and they flourish very well every year!

  7. Ginny says:

    Help, Margaret! In one of your posts (last year??) you gave a source for the floating plants you use in your pots w/standing water. I carefully saved that source and now, of course, I need it and can’t find it! can you help? Love your blog and the new book!

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