WHEN I LAST TALKED to Doug Tallamy in February 2020 around the publication date of his book, “Nature’s Best Hope,” I didn’t want to go on and on about the advice in it regarding smart fall cleanup, which is one of the ways I know I’ve dramatically shifted the way I manage my own garden compared to 10 or even five years ago. But we were looking ahead to spring then, not fall.
But now’s the time, and I’m grateful that Doug returned to the podcast that fall to do just that. Want to plan your most ecologically minded garden cleanup ever, and understand the consequences of each potential action you can take?
The subtitle of University of Delaware professor Doug Tallamy’s recent book, “Nature’s Best Hope,” is “A New Approach to Conservation that Starts in Your Yard.” Meaning: The choices we make all year-round, including the very important one of how we clean up in fall and again in spring, can help counteract an overdeveloped, fragmented landscape that puts the food web to the test. You and I are nature’s best hope, and I’m glad Doug joined me again to help us learn to support it.
cary institute’s free doug tallamy webinar-lecture on 10/27/23
Plus: On Oct. 27, 2023, at 7 P.M., hear Doug either in person or virtually online in a free lecture hosted by Cary Institute in Millbrook, N.Y., co-sponsored by Millbrook Garden Club. Learn more and sign up by clicking here.
Read along as you listen to the October 5, 2020 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Spotify or Stitcher (and browse my archive of podcasts here).
Plus: Enter to win a copy of the new book by commenting in the box at the very bottom of the page.
Extra: I also wrote about fall cleanup in my column in “The New York Times” with help from two Cornell experts last week; you can find that story here to round out the coverage.
a saner, greener fall cleanup, with doug tallamy
Margaret Roach: Thanks, Doug, for being back.
Doug Tallamy: Oh, it’s great to be here, Margaret. Thank you.
Margaret: Yes. Before we start, I have to say, we’ll have a book giveaway … and also that I was agog when I saw that you have another book coming in the new year, on oaks. You never stop. [Laughter.]
Doug: Yeah, well I’ve actually stopped now. It’s been a while since I wrote anything. It takes a long time for these books to get out. I gave it to Timber [Press], well gee, I don’t know, seven, eight months ago, and it’s not going to come out until next March.
Margaret: Well, I’m very excited about that.
Doug: But yes, it’s called “The Nature of Oaks”.
Margaret: Yes, yes. So to get to this sort of subject of ecological cleanup, just to set the stage for everyone, maybe some people haven’t seen your book—either of your books. You and your wife, Cindy, have a large home landscape, I believe, and have been managing it with a very environmental, gentle hand, and I wonder if you could describe a bit for us first and tell us a little bit about your approach there at home?
Doug: Well, we live on a farm that had been in operation for almost 300 years, and then broken up as they are these days into 10-acre parcels, so we have one of those 10-acre parcels. But before we moved in, the last bit of farming was to mow it for hay, which really in those days was mowing a bunch of rootstocks of invasive plants like multiflora rose and autumn olive, and then you call that hay.
Doug: So before we moved in, they had stopped mowing, and all that stuff had grown back. So almost every plant on the property was from Asia. So we made it a goal to fight those invasives, to reduce their number. I mean, Cindy does most of this work and she’ll always say, “They’re not all gone.” Certainly the big old bodies are gone and we do get… The neighbors haven’t done it, so we get seedlings coming in every year.
But by and large, we’ve returned it to a native state. Is it exactly what it was like 300 years ago? Probably not, but we have lots of very productive native plants.
And the goal was to reestablish the relationship between those plants and the animals that use those plants. That’s what we call the food web.
The thing that I try to impress upon people is the most important job that plants have is to capture energy from the sun and turn it into food. If that food doesn’t move out of the plant, in other words if something doesn’t eat part of the plant, it’s locked up in the plant and it has gone to all that trouble essentially for nothing. So to see a little bit of your leaves eaten: that’s a good thing. It means something else has benefited from the sun’s energy, and that’s what we’ve tried to encourage on our property.
Margaret: O.K. So here we are, it’s approaching October as you and I are speaking—momentarily—and leaves fall, as they say. Leaves will fall; it’s almost time. So let’s start there with a little bit, sort of a short course, in the ecology of leaf litter, of what happens when leaves are on the ground.
Margaret: Or maybe before they leave the ground, in fact, because that’s really where it begins–when they’re on the trees, the native trees, especially. [Below right, a stick caterpillar probably of a Geometrid moth, hiding in plain sight on a bottlebrush buckeye twig in fall at Margaret’s.]
Doug: Yeah. One of the things we’ve learned in recent years is how important caterpillars are to that food web. They’re the major group of animals that are transferring energy to birds and other animals.
Well, they’re developing on the leaves of our plants. Many of them will make their cocoons. They’ve got to spend the winter in some state, and most of them spend the winter as a pupa, or wrapped up in a very tight cocoon, or as a bare pupa. Well, a lot of those cocoons are rolled up in the leaves. So for example, the luna moth that just ate your sweet gum leaf, I mean a beautiful moth, well it spins a cocoon in the leaves that it was eating and then that drops to the ground. And so do all the leaves drop to the ground, carrying so many of those caterpillars in their overwintering state.
So when we rake up those leaves and burn them or put them out for the trash or make sure there are no leaves on our property, we’re throwing away all the life we just created, or a lot of it anyway. So what do we do with those leaves?
I like to think of leaves the same way we think of water these days. The practice is to keep all the water that falls on your property. Don’t let it run off. Same thing with leaves. So all the leaves that fall on your property should stay there, because that’s part of the cycle. They’re going to return the nutrients that were taken up by the trees’ roots and used all summer long, they’re going to return them to the soil so the tree gets to use them again. Leaves are the perfect mulch. If you rake up your leaves, throw them out and then go buy bark mulch, or something else, it’s better than bare ground, but it’s not nearly as good as leaves.
So you want to rake up your leaves, I mean, I get it. You can’t leave leaves on your lawn if you want to have a happy lawn. Of course I’m suggesting that we cut our lawn area in half, and a great way to do that would be this fall, when your leaves fall, create beds of those leaves around each of your trees. That right away reduces the area that you have in lawn. The leaves will smother the grass, so you’ve got instant beds right there. Then you can plant in them or wait till the spring and start planting in them. The ideal mulch really is a living plant, where you have so many plants on the ground that you can’t even see the ground, and then the leaf litter is underneath that. A lot of people worry that if you don’t rake up your leaves, your spring ephemerals or other plants won’t be able to germinate through them.
And if you have 3 feet thick of leaves, that’s true, but in a normal leaf fall with normal 3 or 4 inches, that’s not true, they come right up through them. I’ve got good pictures of bloodroot and all kinds of other things this spring coming right up through the leaf litter. Delicate things like phlox, they’ll do the same thing. So our efforts to get rid of every single leaf so it doesn’t smother our plantings, we’re too zealous in that regard.
And then of course during the summer, some of those leaves break down and return those nutrients. They keep water, they keep moisture, in the soil. There are actually more species of organisms that live in the soil than live above it. It’s a vibrant ecosystem, but we can’t allow it to dry out. And if we have bare soil, it dries out, and it blows away, and it erodes. So leaf litter is the perfect protection for our soil community, which then encourages our plants, our root growth and mycorrhizal interactions.
It also encourages carbon sequestration, by the way, which is an extremely valuable ecosystem service these days. So those are just some of the important things that leaves do, and we want to keep them on our property.
Margaret: And you talk in the book about what you just described, where you let those leaves create sort of beds around where maybe there’s grass growing right up to the trunks of trees. Create these beds with the leaves that fall; let the leaves do the mulching job and so forth. You call them “creating pupation sites for caterpillars” like you were just talking about where they can go through their next phase. They can overwinter and go through the next phase of metamorphosis.
But what I find even also interesting is that… and caterpillars are so important because they’re such a big food for birds and baby birds, and so forth, but everybody’s in that leaf litter. I mean, there’s like ground-nesting bees and there’s millipedes, which I have a particular obsession with, millipedes who I guess are some of our recyclers of the detritus on the floor. [Above, Apheloria virginiensis corrugata, a millipede, at Margaret’s.]
Margaret: And there’s spiders—and everybody’s in there. It’s like a whole world in there.
Doug: That’s right. That’s right. And if you get rid of those leaves, nobody’s in there.
Doug: But yeah, that’s a major point. Those are our decomposers, the decomposer community that recycle nutrients very quickly. And there are hundreds of species of them in your yard, and tiny little things, all the little mites that are down there, they’re all turning over those leaves so that they can be taken up again the next year as nutrients.
Margaret: Yeah. And I mean, you get rid of your spiders and you get rid of pest control. I mean, they’re such helpers. And you get rid of your bees, your ground-nesting bees and you get rid of some pollinator services, so we’re kind of shooting ourselves in the foot.
Margaret: I mean, yeah. So you and Cindy are out there and she’s dealing with the invasives [laughter]. Can you send her up here?
Doug: Yeah. I’m looking out the window right now at her. She’s outside working hard. [Laughter.]
Margaret: So what about weeds? What about “weeds?” Because at this time of year, there may be seed-laden weeds in the garden, and so how do you two apply judgment to… So for instance some non-native weed, like I have a Galinsoga ciliata, a weed that comes in with ornamental plants and from farms and so forth. It has a lot of little flowers now, and it’s going to make seeds. I pull that; I don’t leave that. However, I have clearweed and jewelweed, the native Impatiens, and Pilea pumila. I may leave areas of those. Do you do that? Or is that silly?
Doug: Oh, yeah.
Margaret: Tell me about that.
Doug: No, absolutely. That’s another benefit of leaves I didn’t mention, is that if you have a good leaf cover, it prevents the germination of a lot of those weed seeds. Our major weed invasive right now is Japanese stiltgrass. It is a tough one, because it is everywhere. It not only makes seeds in a typical grass way, right at the tips of the leaves, but it also makes seeds at its axils. So even if you mow it, you say it’s an annual, then I’ve gotten the seeds, you haven’t gotten the seeds. You’ve gotten some of the seeds, and it will germinate again next year from all those seeds.
But leaf litter is one of the things that depresses the growth of Japanese stiltgrass. So again another reason to keep those leaves around. But sure we keep our Jewelweed and any of the natives that we want to encourage.
So for right now, we’ve got a very good bloom of white snakeroot. It’s beautiful, don’t eat it [laughter]. It’s not good for you. But the Japanese stiltgrass has come in and crowds it, so what we do is we weed around the plant so that when the seeds fall, it has mineral soil on contact. That’s how we encourage spread. And Cindy has done a wonderful job of that, of spreading a lot of our herbaceous natives by making these weed-free zones. We have 10 acres; we can’t weed the whole thing. But we do weed the areas that we want certain things to expand in.
Margaret: Right. That snakeroot is an amazing plant. It used to be called Eupatorium rugosum, I think. And I think it, maybe it has a new name that starts with an A that Margaret can’t remember, but whatever. [Laughter.] [Note: it is Ageratina altissima.]
Doug: Neither can Doug.
Margaret: Good. If they just would stop changing the Latin, I’d be in better shape, Doug.
Doug: Yeah, just stick with the common names.
Margaret: But yeah, that’s a great one, that’s a great one. And I’m noticing that as I’ve unmowed, following your guidance over the years and the inspiration in your books, as I’ve unmown more and more of my place, I’m finding that that is one of the things that’s coming in, from sort of the woodland edge. And so I’m enjoying seeing right now at this time of year, as you said, that those sort of islands of white bloom and insect activity relating to it and so forth, something I didn’t have as much of before.
Doug: People are always looking for something that will bloom in the shade. That will. Most of our snakeroot, I mean it does really well in the sun, but most of it is under some kind of canopy cover and it blooms wonderfully. So it’s a great, great fall color in a shady area.
Margaret: Yes. Then there are also some plants that in the book, you speak a little bit about, that if we prune them at the right time, not too soon, that they can serve as an invitation to some of these important insects. Plants that have pithy stems that creatures can inhabit and spend the winter in and even reproduce. Could you tell us a little bit about some of those examples?
Doug: Yeah. Most of those creatures you’re talking about are native bees. We have 4,000 species of native bees, 70 percent of them nest in the ground, but 30 percent nest in what you call pithy stems or woody stems that are easily excavated. So very soft wood, like elderberry branches.
And it’s a challenge the way we garden. Because for example, if you have an elderberry tree or bush and a branch dies, what do we do? We prune it out, and you’ve just removed the nesting site for the bees that would normally enter the stem and then tunnel horizontally and then they reproduce within that stem. And the last generation of those bees is what spends the winter. So if you prune it out and throw it away, you’ve probably killed that lineage of bees.
One of the things that Heather Holm has discovered last year I guess it was, we know that a lot of native bees spend the winter in the pithy stem of things like goldenrod, anything that they can hollow out at the stem, so most of our meadow plants—evening primrose, all of those guys.
And I always thought that they would do that right now, they would enter those stems and their last generation would turn into a pupa or pre-pupa, actually, and then they’d spend the winter that way. She says, no, that’s not what’s happening. What’s happening is those stems will sit there all winter, and then the next spring, that is when the bees start to use them. And they use them all summer, and those old pithy stems are what the bees spend the winter in.
So they’re actually a year old when they do that. So when we mow down our meadow plants in the spring or any time, we’re eliminating those overwintering sites for native bees, which is why we recommend if you have a meadow that you only mow or burn a third of it each year, and you leave the other two-thirds just as it is.
So that it’s a three-year cycle before any one area is treated. That way there’s two-thirds of your meadow that can help recolonize the area you did treat.
I mean, in this part of the country, we have to mow or burn, because it won’t stay a meadow; it’ll become a forest if we don’t. But that’s an important piece of information. She also found out that most of that overwintering use happens in the first 2 feet. So if you have a tall, let’s say you’ve got tall New York ironweed and it’s dead and you don’t want it to sit there, you can cut it off, but leave 2 feet next to the ground, because that is what they will use the following year.
And the top part, the more unsightly part, can be removed, but don’t do that until the early spring, maybe the end of February or early March. Because the seeds that those plants make is what sustains our juncos and our white-throated sparrows and all the birds that move south. Our goldfinches—the things that are eating seeds all winter long depend on those plants, and when we deadhead and cut them off in the fall, we’ve removed that seed stock.
Margaret: Yeah. Here in the Hudson Valley of New York State, the white-throated sparrows in numbers have just sort of resurfaced, and they’re picking through exactly what you’re saying, anything faded. I don’t see them so much in the summer and I see them right around now. [Above, white-throated sparrow from Wikimedia.]
Doug: No, no they migrate; they go north.
Margaret: Sure enough last week, or the week before, they started showing up, going through the spent meadow plants and anything else sort of weedy that has already set seeds, and they’re hungry and they’re happy to find all this goodness.
Doug: A lot of people say, “Well, I feed the birds. I put food out in the feeder,” but there are birds that won’t go to feeders, and sparrows are one of them. White-throateds never will. It’s interesting, I’ve been watching our juncos over the last 20 years, and every year there’s one or two more juncos that actually do go up to the feeder. It seems like they’re learning there’s all this good food up here. Otherwise they’re always on the ground. So don’t think your feeder is going to solve everything. You need to have those plants with the seeds.
Margaret: Right. No, you’re right. And I have noticed the same thing about the juncos, who I always categorized as ground feeders, like mourning doves, or like the sparrows, as you say, ground feeders, but you’re right. I see them almost as perching birds now. Some of them do go up to the feeder and it still surprises me.
Margaret: So one of the other things just quickly, what about a brush pile? I see that over and over again recommended: We should have a brush pile; we should have a brush pile. What purpose does that kind of sort of messiness to use a loose term, what does that do? What kind of a place is that?
Doug: Well, it does a couple of things. First of all, one thing we don’t tolerate typically in a typical suburban yard is any kind of, we call it coarse woody debris. You know, if a branch falls you’ve got to get rid it. Well, if you stack all those up in one place, first of all, that is a site where many of these stem-boring bees will, they’ll tunnel in there and they’ll spend the winter in there.
It also provides, if it’s a big enough brush pile, it provides winter cover for many of the birds we just talked about. So if you get a big snow, they dive into those brush piles and they weather the storm. They make little cavities. It’s also a wonderful place for them to dodge predators. The sharp-shinned hawk comes down and tries to grab them, and they do their best to get it into the brush piles as cover.
And same thing with the foxes and everything else that try to get it. It’s a rough world out there. Everybody’s trying to eat everybody else.
Doug: So we’re providing cover and shelter from the weather with those brush piles. And there was something else: If you let it degrade over time, you’re taking all the energy that was in those stems and returning that to the soil as well. If you remove a brush pile that’s been there three or four years, the soil underneath it is just wonderful.
Margaret: And even more so, if we would stop taking down trees and carting away their carcasses—shredded, chipped, whatever—but let that biomass return to the place where it grew up. I’m really, over the last probably 15 years or so, I mean, obviously if a tree is in danger, it’s going to fall in the house or something that’s one thing. But I’m more stabilizing things and leaving as much of the biomass in place as I can. Do you know what I mean? As opposed to cleaning up, cleaning up.
Doug: Absolutely. Either if it falls, it’s a log on the ground underneath that is where the salamanders going to live and the toads will hide.
Margaret: It’s amazing.
Doug: But having it standing as a snag is even better. They are doing this down in the Southwest in Texas for example, there’s a lot of very tall loblolly pines that are unstable. So they’ll cut them off, maybe 15 feet up, so it’s this pole, but they’re leaving it there. It’s rooted. It’s not going to fall anywhere. And birds start to nest in that trunk immediately. Things like brown-headed nut hatches. We could do that here as well.
Margaret: Well, I definitely have more snags than ever because again, 20, 30 years ago you called the arborist and said, “Take that down. It’s dying,” and erased it. And I don’t do anything like that anymore. And so I have these totems, and boy oh boy, the pileated woodpeckers, they love them. [Laughter.]
Doug: Yeah. Yeah. Good place to hang your suet.
Margaret: Yes, yes, yes. So we just have a minute or so left and I just wondered, anything different that you’re doing this fall or any project in your home garden, you and Cindy besides weeding [laughter]? Anything else going in?
Doug: We planted so much when we moved in, we forgot the basic rule and that is that plants grow. So I’m actually doing some editing this fall, trying to get a little bit more sunlight on the property. We’ve had such great success, everything’s grown, that I’m losing my sun and there are areas where I don’t want to do that. So I’m doing some editing.
But I have one more request for listeners. Typically the fall is the time you’re going to fertilize your lawn, and that’s what everybody recommends.
Doug: This would be a great time to break the fertilizer habit altogether. You never have to fertilize your lawn. You do if you’re going to win lawn of the month awards, but we’re not going to do that anymore. Cut your lawn frequently, the area that you keep, and it will stay relatively weed-free and it’ll be nice. You don’t have to put the fertilizer on, because the fertilizer always contains herbicides that’s going to kill any broadleaf, any clovers, something that might benefit the bees. And most of it just washes into our watershed. So save yourself time and money skipping the fertilizer; our North American plants don’t need it.
Margaret: Yes. Well Doug Tallamy, I always learn so much from you, and I appreciate your making the time I know in your very busy schedule. So thank you, thank you. And the book is “Nature’s Best Hope,” and I hope I’ll talk to you again soon.
Doug: Oh, anytime you want Margaret.
more from doug tallamy
Extra: I also wrote about fall cleanup in my column in “The New York Times” with help from two Cornell experts last week; you can find that story here.
enter to win a copy of ‘nature’s best hope’
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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 10th year in March 2019. 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 October 5, 2020 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).