- So as I go out into the park, near my house, I notice there's so much privet and honeysuckle. It really dominates the landscape. I think about it, and I think some point people bought those plants thinking they'd be great in their yard, but now it really is threatening the natural biodiversity out there. - Right. As gardeners, I think we all want to be good stewards of our land, not just ours, but beyond our property and surrounding neighborhoods. surrounding parklands, wherever. But as a gardener, that leaves me with a question of what do I grow? Is it only native plants or are there... Can I still you a good steward and grow all of the plants that I love? On this special episode of "Volunteer Gardener" we are going to hear from experts and an audience of gardeners about these topics, about how to be a good steward and a thoughtful gardener. I want to introduce our panelists, Steve Manning, who is the President of Invasive Plant Control. Richard Hitt, who is the President of the Middle Tennessee Chapter of Wild Ones, and Matt Dawson, who is the owner of Samara Farms, Wholesale Nursery and Natural Creations Landscape Company. So guys, thanks so much for being with us today. - And so I got very curious talking to people about how do you define this? I think that's a good place to start. There is actually a federal executive order that has to do with invasive plants, and it gives us this kind of guidance. We're looking at... First of all, we've gotta talk about, well, what's native? Well, a native species is going to be something that has existed since a certain period of time in a particular region. Generally, the time period in the United States that we look at for native plants is to say the time before European contact. So that's maybe a little arbitrary, I'm not sure. But what do y'all, y'all agree with that one? - I think it's a simple definition, but it doesn't really capture the important part to me, which is co-evolutionary relationship with the other plants and fauna in the area. But that gets a little complicated, so I like the simplicity of this. But it is a little arbitrary to just pick a particular moment in time. - First, let me back up to non-native. So that's easy, right? It's just not native since that particular time point to that area. Non-invasive species, they are not native. So if you've got a problem with your Jerusalem artichokes spreading around like me, they're not really technically invasive, they're just aggressive. It has to be non-native to that eco-region, and secondly, that it is going to cause some sort of harm to the environment. Or actually we talk about to human health or to the economy, basically. Poison ivy and pokeweed are both harmful to people, right? But they're not invasive. And in fact, poison ivy really great for the wildlife, if you keep it away from you. And then not native side, we've got gingkos, which they were around a very, very long time ago, but sort of in our general time period. And basil. And then we have Callery pear and the bush honeysuckle. This is really important to know. This list of things, you can't sell in Tennessee, you can't propagate 'em for sale in Tennessee. These are the big no, no right now in Tennessee. Do y'all have anything to add to that about the legislation on these? - Well, some states regulate the sale of plants much more strictly than Tennessee. So for example, in Oregon, they have a much longer list of banned plans and they enforce it pretty well, as I understand it. But other states do, I think we're somewhere in the middle, but I think we could do a much better job. We shouldn't be able to go to the nurseries and buy as many invasive plants as we can, presently. And by invasive plants, I mean, specifically the ones on the Tennessee Invasive Plant Council list. - The invasive plants entering the state aren't just the nurseries, but it's the garden centers that order elsewhere, it's the mail order catalogs that you can buy things from. And there are just too many options to acquire plants. Even if we had more legislation, the enforcement of the legislation is difficult to stop, often spread of things because of just those reasons. - There are all these fantastic groups around the country that are invasive plant and invasive species councils. And they have different lists that may have nothing to do with legislated lists, but they're looking very carefully at what kind of they are known threats already. And then this thing that I find terribly confusing is emerging threats. - A plant isn't necessarily uniformly invasive. It might be invasive in west Tennessee, that would be well behaved in east Tennessee. And so the Invasive Plant Council, which I'm not on, but their rule is if it's been reported in, what is it, fewer than 10 counties in Tennessee as invasive, then they consider it an emerging threat. But if it's been reported in 10 or more, it's a established threat. So it's established more widely across the state. And then we should probably consider and watch it closely and consider banning it from introducing to the state. - What really is the problem with invasive plants? What problems in the native landscape, our parks, and our natural lands do invasive plants pose? - How about the Warner Parks? Let's just call it around 3,000 acres. It has a beautiful over story, lot of wonderful native trees. It also has some invasive trees that we have to really pay attention to. But the under story is, if you've been there, full of bush honeysuckle, Chinese privet, And if you look at list, just to kinda back track just a little bit, and you have 300 species that are listed and they're under all these categories, generally speaking, and we work from Florida up to Maine out to Oregon, the states we go to, there's usually 10 or 12 of those species that we're working on. The rest of them, we're keeping an eye out for. We're paying close attention to, to make sure they don't come in. And the same goes for the Warner Parks. So if we have some type of major event, windstorm, a tornado, something knocks down trees, what's gonna happen where that space is open all of a sudden? We have this new pallet that the forest is gonna work with. Right now in the large portion of the Warner Parks, we're going to have bush honeysuckle, Chinese privet, euonymus, Japanese stillgrass, Ailanthus altissima, that's what's gonna fill in that space. It's not gonna allow seeds from any other plants to get in there and grow because it grows faster, it has very few natural enemies, if any here, and they just take over. So the Warner Parks is under siege because of that. The neighborhoods around it are kinda pushing in with their invasive plants. So the goal is to push out from there. - As this goes on, we lose our native plants and that has an impact all the way up the food web and biodiversity. And we've seen lots of reports over the past years, and they get worse each year about the rate of decline of biodiversity. It's not only going down, but according to the UN studies lately, it's going down at a faster and faster rate. And so that's a total recipe for a disaster. A curve that's going down, but it's going down faster and faster over time. - Another problem with a lot of invasives is that although they're non-beneficial to some animals and wild life, the reason why they spread so rapidly is because animals are eating them and spreading them. Like the birds are eating a ton of the privet seed and then flying and spreading it. So it's not as if it's being spread by man into the woods. That's the vector, that's the way it gets there. And it is a problem because it does definitely choke out some of our natives and becomes a monoculture. And those are the ones that... Well, I chose privet to be one of the worst, I feel for Tennessee, because I see it. Natural Creations, my landscaping company has spent a lot of time in the adjacent area of Belle Meade and the homes there trying to eradicate it. And because we know that it's a problem, and they want it out and we want it out. The deer also are a problem, so it is feeding the deer. When we eradicated a lot of it, we started having deer disease and deer problems. So because the animals now are feeding on that instead of other native things, and the population has a huge food source, So when we eradicate it, we do create a new problem. And so it's a balancing act. And I think everyone can agree that anytime you do one thing to nature, it's gonna respond in another way. An ecosystem that's there now is, although a monoculture, it's functioning with the animals that are there. Do I think we need to eradicate it in areas where we can control it? Yes I do. - And there's good examples of, once the invasives are removed, you don't always have to go in there and plant something. There's a seed bank of native plants that might have been there for 50 years from lots of spicebush, lots of paw paw are coming into the Warner Parks. So at a distance you look out there and you might still think, "Oh, there's still honeysuckle." But when you get closer, you realize, "Wow, the eradication actually worked." There's one volunteer there that worked there for, I think, five years, just hand pulling bush honeysuckle in large areas by deepwells. And you go back in those areas now and there might be 5% of that came back with invasives. The other stuff is all native that came back in. - I got permission for my HOA to treat an HOA part behind my yard. It had just every invasive we've talked about except Ailanthus. So in the spring, I removed mostly the bush honeysuckle, but also the privet and just walked away. And in the fall we had whitecrown beard, Verbesina virginica coming back up loaded with butterflies, loaded with bees and wasps. And so the seed bank was there, and so as soon as I cleared the light protection from it, it came up in great numbers. - Well, we noticed when we're clearing privet out and honeysuckle out, the seed bank is full of more honeysuckle and privet. And often when you're trying to eradicate, you cut it down once and then you've got this just a plethora of seeds coming up and it's even thicker than it was before. - There are nationwide, I think, roughly 1,300 plants that are on some kind of invasive species list. And a lot of that is regional. It doesn't mean that there are 1,300 plants here in Tennessee that are invasive. But nationwide and in a regional way, that many. And we talked a little bit about plants coming back and forth across state lines and that sort of stuff. So about 60% of those species that are on a federally invasive list somewhere are still available on the market. So I will be the first person to say that I'm not much for the banning of very many things, but these plants that really are invading our natural areas and causing perhaps irreparable harm, what are some of the ways that we can think about, as we go forward, continuing to be good stewards? I mean, that's really what this is all about out. - So we can ask for it, and that's one way we can approach it. The other is for organizations to work together. I'm past president of TLA, and when we started making the invasive species board here in the state, they consulted the nurseries and we had discussions on it. I don't think those discussions continue today, and I think that's a critical thing to occur. There has to be communication somewhere between the science of the plants, the industry that grows it, and the education of the people and the landscapers. - The only way in this country or in this world we're gonna get a hold of invasive species at the local level, which I think is very important, is to make sure that everybody's involved. One point you made was education. When the executive order was signed in 1998, that was about the time that people started paying attention to invasive plants. I went to just about every national park in 1997 when I was starting my business. And I couldn't find someone that knew what an invasive plant was. They couldn't even tell me what it was in most parks. If you go there now, every park has a staff of some sort that deals with invasive species on their properties. Education has worked over time, and that filters down into neighborhoods, it filters down into the local parks. At the Warner Parks, they have a wonderful volunteer program. So the volunteers spend a lot of time out there, and you'd have to quantify that with a dollar amount, because they do a tremendous amount of work out there. And it also depends on the species you're treating and how long it takes to treat a certain species and the density of that species. Parks like the one in Georgia, I couldn't see my hand in front of my face, the privet was so thick. Maybe a hundred stems per square yard. And if you contract something like that out, that might cost about $6,000 an acre to cut and treat that. If you were gonna come through and foliar spray that, it's gonna cost much less. If you're gonna come through there with a mulching machine and chop it all up and then spray the resprouts, it's a totally different price. At Warner Parks, we're trying very hard to do a lot of different things. And we're considering how to use grazing out there in certain scenarios for follow up treatments. We've just purchased a hot water treatment machine that is very expensive, but it doesn't use a drop of chemical. We go out there and we're able to actually kill weeds with hot water, certain species. We're using it on the euonymus, we're using it on English Ivy that's on the ground, vinca. But I think you can look at a whole park like that, if it was my guess, and that park was 70% infested with Bush honeysuckle, privet, and the different species we're talking about, that might be over the course of the long-term, a five to $6 million project to knock that out. - So I'm not in the industry, but I'm more on the educational side with wild ones. But we've considered several things, and one that I like a lot is to inventory the plants in a given nursery and see how many of those are on our invasive plant list for the state. And then enter into a conversation with the nursery and present to them that if they would remove those from their inventory, we could put a certificate of compliance on their window or grant them some kind of recognition and then promote them in a better way to our members. - We need plants, we need plants in our urban areas. It's been noted again and again, where landscapes are unkept, they have a higher increase of people with depression and a higher increase of crime. So they calm us. We need them. And we need to work with plants that will work in that site, whether it's native or non-native, it is site specific for a plant. And that choice is why you choose an expert, and you seek expert help. And unfortunately, not all landscapers are experts because it brings it to the point that we don't have, anyone can go get a landscaping license or a business license as a landscaper. That doesn't make sense to me. I think we really need to ask our state government to please require some form of certification to be a landscaper. Your plumber is certified, your electrician is, but your landscaper is not. So do your research, find out, ask him questions, ask him where he got his education because that's important. Our industry needs to change. And it can only change when the government helps us change it. - From a nursery production standpoint, not everything is easy to grow. And I'm gonna come back around to Bradford pear for just a minute. Because it's really not Bradford pear that is the problem. It's the Callery pear, which is one of the parent species. Bradford when it was introduced in the late '50s, early '60s is actually a self-sterile cultivar. On its own, it will not produce fruit. The problem is, from a nursery production standpoint, we graft a lot of plants, especially trees because it's the quickest and easiest way to produce them in the field and get a lot of stock. The easiest root stock to use is seedling Callery pear. You're never really going to let that pair grow. So in theory, it won't be a problem, but when your Bradford pear reaches the age of 25 and a windstorm comes through and splits in half, what's left is the root stock. And that root stock grows into a wild Callery pear, and that wild Callery pear produces seed. The other thing that happened with Bradford was, as long as it was the only cultivar on the market and it was self sterile, that wasn't a problem. But when we started seeing other varieties from other gene banks like Aristocrat and Whitehouse, and there are 15, 20 cultivars out there that through the '60s, '70s, and '80s were introduced to the market, they could then cross pollinate with each other and Bradford became a problem because it would set fruit and copious quantities of it. 30 or 40 foot Bradford pear, maybe it has a 100,000 fruits on it. I mean, that's not an exaggeration. Every one of those fruits has a five carpel seed section in the middle of it, so you're talking about a 100,000 fruit. With five seeds in a fruit, that's a half a million little fruits, little seeds that are produced by a single tree. - This is such a frightening story to me. So what do we all need to know when we hear those stories? Is it something that a nursery person says, "Yeah, this is not going to become invasive "because it is sterile but we hear these stories." I don't know, what do we, who are just plain old gardeners, what kind of questions do we need to ask? - So educating those garden citizens is critical. So we can talk about educating the nurseries all we want, which I'm trying to do, but the Federation of Garden Centers needs to also try to educate, and maybe a garden center needs to have, for certification purposes, better knowledge. And then the garden center can buy from any state and ship it in. And that's part of the problem. - If we as gardeners are going to the big garden centers and saying, "I'm not gonna buy that," in mass they're gonna start trying to find something else to sell because they have to sell. But at the same time, what you're saying, the education part it falls on us to educate the gardeners and the general public, "These are the places you can get the native plants, "these are the places you can find alternatives. "You need to go check out those as well." - Is there all kinds of great plants out there? And really it's very few of non-natives that go crazy and go invasive, right? - Right. In Tennessee, we have approximately 400 species of non-native plants that have naturalized, and only 50 or so are not playing nicely. There is some scientific concern about these mostly sterile cultivars that are being introduced into the industry. But the jury's out on that. I kind of feel like we give the nurseries the benefit of the doubt on that, with butterfly bush, For example. If they've gone to the trouble and expense to come up with a cultivar that's nearly sterile and they're willing to pay and they're willing to introduce that and stand behind it, I don't have a real big problem with that. But there's some botanists who know a lot more than I do and they're really worried. - So I'm curious about herbaceous plants versus woody plants. - I think one of our worst enemies we have here in Tennessee is Japanese stillgrass. And if you look along the waterways, really anywhere there's a human path, you're gonna find Japanese stillgrass growing, where it's been disturbed. There've been parks where they've been pristine, some state parks in Georgia, just beautiful forest. They come in, they build a trail where they bring in gravel and sand. The gravel and the sand has some stillgrass seed in there, now the whole forest floor is covered with Japanese stillgrass. - Vinca minor's on my list. - Especially in the parks. - Yeah, it spreads, and it's in the dogbane family, so the goats won't even eat it. It's almost impossible to hand remove. So where it occurs, I don't know a safe way to remove it. If I had to remove it, I would do a foliar spray. But in the areas that I volunteer, we don't do that sort of thing. - Well, and even that with vinca minor is difficult because it has such a waxy cuticle on the leaf that a lot of times, and euonymus, it sort of just rejects that chemical that you're using on it. - On the point of cultivars, you have to think about whether they can cross pollinate or not. And a lot of the cultivars are selections that are made because a lot of seeds were put out and they chose that one from a native selection because it was more resistant to insects and we can spray less. To me in my personal opinion, I feel that if it's gonna cross pollinate and it's just unique as you are to me and everyone else in this room, biodiversity is what we're after. And that helps because these definitely have something different in them from the other gene pool. And if it's a stronger plant and it grows well without much need, that's what we wanna do. Like if, not speaking of apprentice, but say dogwoods. Selecting a Dogwood now that needs to be resistant to Dogwood anthracnose, the leaf spot to all the other problems that it has would be great, 'cause we're losing it in the population. If that Dogwood then can cross pollinate with others, wonderful. Another example is the elm tree, We lost it to Dutch elms disease. But there are elm trees that have been selective, that native are alive, that are out there on the market today. And if we keep planting those and we keep finding more in the wilderness that are alive, we're gonna maybe bring that tree back. So that's what we're after in horticulture. That's the idea behind a lot of what we do is not just to find the newest plant and the prettiest color, but also protect our native plants. And so, yes, I do support nativars as long as they're being thought of in a way of the right way and used the right way for beautification. Because not every Itea seedling looks great. And therefore, these are plants that are native that you can put in your yard and get that beautiful landscape. - There is a cultivar of phlox paniculata called jeana, J-E-A-N-A. That plant was discovered in Williamson County, about five miles from where I live by a woman by the name of Jeana Prewitt. And it was eventually named for her. Phlox paniculata jeana is completely powdery mildew resistant. I've grown it for 15 years and I've never had powder a mildew on it. I have never sprayed it. It also is resistant to the leaf spot that a lot of phlox paniculata get. The difference between it, as a wild selection, and most of the cultivars that are on the market is the flower is about half the size of a normal phlox paniculata but the flower in fluorescence, the flower head is almost twice the size. I grow about 13 or 14 cultivars of phlox paniculata in my garden. The butterflies will pass up every other one, including the straight species to go to jeana. I have counted on a clump of three plants, as many as 40 tiger swallowtails at one time. I don't know if it produces more nectar, I don't know if there's something about the flower that is more attractive, but I can tell you that not just the tiger swallowtails, but pretty much any butterfly that is in my garden in the summertime will fly past every other phlox in the garden to be on phlox paniculata jeana, for whatever reason. And it's disease resistant, it's drought tolerant, it's just, I can't say enough good things about that cultivar. We do hear a lot of talk about only growing species, but I think there really is, Matt mentioned Itea, as a landscape designer, if I didn't have Itea little Henry, some of those other dwarf cultivars, my only options would be Itea that is six to eight feet tall. And half of them lose most of their foliage by August because they get a fungal disease on the leaf. So there's a lot to be said for cultivar selection, from a landscape industry perspective, from a designer perspective, from a nursery perspective, where those cultivars, those selections, even though a lot of them are from wild populations, they have been selected because they're better in some way for the nursery growers, for the homeowners, the standpoint is sort of being good stewards of our earth. What are things that we as homeowners can do? - When it comes to plants, people are a little bit scared of two things. First of all, they see invasive plants, Chinese privet in their backyard, and they think I can never do this. I'll say it's very manageable, it's very doable, don't be afraid. And there's plenty of help out there. Talk to Invasive Plant Council in Tennessee, it's a great option. Talk to one of us, talk to a lot of people, and they'll show you how to do it, or they'll help you do it. Secondly, there's a lot of great places that sell many different types of plants besides the four or five that you might find at a big box store or something of that nature, which would be some great options. So don't be afraid to go out there and do it. - You can make your garden... You can step back from the aesthetics just a little bit and you can make your garden part of the ecosystem and not just a scene taken at space that doesn't support biodiversity. - Excellent. Fantastic advice. Thank you all so much for talking with us today and educating us further.
May 05, 2022
Season 30 | Episode 18
There are parks full of Chinese privet and bush honeysuckle. But not so long ago, gardeners bought these plants at retail outlets assuming they would be good in the home landscape. Now, those plants are deemed invasive, and harmful to the ecology. As gardeners, we want to be good stewards of the land, but what does that mean? How much should we limit our plant choices? Must we only plant natives?
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Home landscapes: benefits and risks beyond the property line
There are parks full of Chinese privet and bush honeysuckle. But not so long ago, gardeners bought these plants at garden centers assuming they would be good for the home landscape. Now they are deemed invasive, and harmful to the ecology. As gardeners, we want to be good stewards of the land, but what does that entail? How much should it limit plant choices? Must we only plant natives?