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Analysis: Gardening and climate change November 15, 2002 IRA FLATOW, host: This is TALK OF THE NATION/SCIENCE FRIDAY. I'm Ira Flatow. Later in the hour, a preview of next week's Leonid meteor shower. But first, are you getting those fall gardening catalogs that are piling up and coming through the mail? I've got mine stacked up, and each year, as I go through the pages, I lust after certain plants. I think `lust' is the right word. I lust after plants that I know I won't be able to grow in my garden because they don't--well, I don't live in a plant hardiness zone, you know. I'm just too far north for these semitropical plants. Let me explain. If you don't know what the Hardiness Zone Map is, the US Department of Agriculture each year publishes a zone map that divides North America into 11 different sections based on the average lowest temperature expected in each area. So that gives gardeners an indication of whether the plants they want to add to their garden will survive. Will the plants winter over? For example, if you live in Portland, Oregon, you'll likely pick different plants than you would if you live in Pensacola, Florida, and those plants from down South, like palms and yuccas and even camellias and magnolias, will just not survive in your Yankee garden. Well, you know, that's what I thought until a surprising new book came across my desk this week, a book that threatens to overturn the conventional wisdom about planting warm-climate plants in colder climates. Just because you live north of the Mason-Dixon Line doesn't mean you can't plant palm trees in your back yard. For example, the cover of this book shows a palm tree that is thriving in Miami, not Miami, Florida, but Miami University in Oxford, Ohio, up north, and there it sits with snow on its palm leaves, and it's thriving. It's amazing. Maybe you've seen this in your own back yard, to a certain degree. You know, if you're a gardener, haven't you noticed that plants that shouldn't be surviving the winter, they're doing just fine? Why is it? Could it be global warming? Are we watching that? Or is there another explanation? Well, this hour, we're going to talk about this change in planting ideology with the author of the book, as well as a scientist who is in the process of updating that plant Hardiness Zone Map. Are the changes they're making a sign of global warming or something else? We'll talk about that. So if you'd like to talk about gardening using--hey, maybe you've got some experiences you can share with us. Maybe you have some palms growing in your back yard. Give us a call. Our number, 1 (800) 989-8255, 1 (800) 989-TALK. As always, if you want more information about what we're talking about this hour, go over to our Web site at sciencefriday.com, where you'll find links to our topic. Let me introduce my guests. Marc Cathey is a former director of the US National Arboretum and the president emeritus of the American Horticultural Society in Alexandria, Virginia. He joins us today from our NPR studios in Washington. Welcome to the program, Dr. Cathey. Dr. MARC CATHEY (American Horticultural Society): It's nice to be here and reveal all about those tropical plants and how they have been a part of traditional gardening. My grandmother in the 1930s had them in her garden in North Carolina, but she had certain rules about where she planted them and how she cared for them. FLATOW: All right. We'll get to that. Dr. CATHEY: But she grew them and... FLATOW: You know, I'm amazed. I've seen this book. Well, let me introduce my other guests and we'll get right into it. David Francko is the author of the forthcoming book, "Palms Won't Grow Here and Other Myths"--a wonderful title--"Warm-Climate Plants for Cooler Areas" from Timber Press. He's also a professor and the chair of the Department of Botany at Miami University in Oxford, Ohio. He joins us today from the studios of member station WMUB on the Miami University campus in Oxford. Welcome to the program, Dr. Francko. Dr. DAVID FRANCKO (Author, "Palms Won't Grow Here and Other Myths: Warm-Climate Plants for Cooler Areas"): Hey, Ira. Good afternoon to you and thanks so much for having me on the program. And hi to you, Marc. Dr. CATHEY: Well, it's good to have a Buckeye from Ohio to work with. It's the ultimate team. When you want to have the A-team, you've got the best you can have... FLATOW: Well, I'll be the judge of that. Let's see how this turns... Dr. CATHEY: Oh, come on. FLATOW: Just joking. Dr. CATHEY: The Buckeye--they're dangerous people. FLATOW: David Francko... Dr. CATHEY: Because they know the right thing. FLATOW: We'll find out. Let me ask him. David Francko, you know, I looked at the book. The cover has this palm tree--Right?--with snow growing on it, and you mention in the flyleaf that there are plants in Canada, I mean, also growing--Southern plants growing in Canada. How can this be? Dr. FRANCKO: Well, yeah. That's right, Ira. Actually, I think the palm you're referring to actually is up in British Columbia... FLATOW: Is that right? Dr. FRANCKO: ...if I remember the cover shot, right? FLATOW: Yeah. Dr. FRANCKO: But the point is a lot of these plants we assume are not hardy beyond a certain hardiness zone when we're using the term `hardiness zone' incorrectly in some cases. And in many other cases, we simply don't have the database to make a judgment on what will grow where, under what conditions and so on and so forth. And it turns out that, as Marc said, if you really travel around the country and talk to people, some of the pioneers in experimental horticulture have been growing some of these plants way outside their accepted zone ranges for a very long time. And so in some cases... Dr. CATHEY: But when you do that... Dr. FRANCKO: Hmm? Dr. CATHEY: When you do that, you've got to define the environment, and so that they can take snow. We have plant palms at the National Arboretum we collected in Formosa, the old word, that are perfectly hardy in the Washington area, but not all palms. It's like everything. You've got to select the right runner and the right combination and then the... Dr. FRANCKO: Exactly right. Dr. CATHEY: ...selection of where they're placed in the ground. For instance, my grandmother in North Carolina, the plants were always placed next to an area where they heated for cooking every day. So there was warmth coming through, and also there was protection from wind and ice, because the dehydration is what normally takes plants out, not cold. So there are factors. Dr. FRANCKO: Exactly. Dr. CATHEY: But the other thing is that with all plants, the map that I've been working on, we're working on a 14-year average minimum winter temperature, and the last 14 years have been--the temperatures have been of a certain range, and we are analyzing that now. In 1980... FLATOW: So you're redrawing the zone map, basically... Dr. CATHEY: Correct. And... FLATOW: ...to be more in keeping the way the climate may be changing. Dr. CATHEY: That's right. But it's not climate. It's average winter temperature. Climate is many things. FLATOW: Right. Dr. CATHEY: And so this is... Dr. FRANCKO: Yeah. Dr. CATHEY: ...one factor. But if you're planning where to grow pole trees in the United States, it'll tell you where you can grow it; also where citrus will be in new areas of the world. So the map is used not only by landscape gardeners but many other people, because it's the only map of the United States that actually delivers detailed information on the county level. And every county name is on the map, which is an amazing thing. FLATOW: David Francko, how did you discover--did you discover by accident that you could bring palms to Canada and have them over winter or was this a whim or... Dr. FRANCKO: Well... FLATOW: ...did you just go to Florida on vacation and have a coconut someplace and brought it with you? Dr. FRANCKO: Yeah. Actually, a little bit of all those things, Ira. We lived in Stillwater, Oklahoma, my family and I, in the 1980s; got kind of attached to the Zone 7 flora of that particular area. And then when we moved to Oxford, Ohio, in 1990, I noticed that there were on the Oxford campus here and in town plants that I would associate with the Southern flora, Southern Magnolias, tree hollies and that sort of thing. And since we had just bought a new house, I started doing some experiments, well, you know, maybe I can grow some of these things here in Oxford. It looks like it might be possible. And as Marc pointed out, you need to take a microclimate approach to growing plants. You also need to recognize that it isn't just winter minimum temperatures that dictate plant survival. Their Heat Zone Map the Horticultural Society's put out is another variable, the amount of heat in the summer and so on and so forth. But what we've done on the Miami University campus--and this is work that Dr. Ken Wilson, my colleague, and I and a whole team of really excellent grad and undergraduate students have been doing, is asking the question, `You know, how accurate are some of these zone rating data that we see on the back of plant identification tags and we also see in gardening books and magazines?' And we have at the current time over 200 species and varieties of the so-called southern woody and non-woody ornamental plants integrated into the campus landscape, and I'm talking about plants that are rated as Zone 7 through 9 in the current literature. And we're evaluating those hardiness characteristics and survivorship and foliar damage and so on in a replicated plot design on the Oxford campus and out in home gardens in cooler areas outside of campus. So we can characterize the plant damage and survivorship and so on very rigorously and down to the microclimatic level that each plant actually exists in on the campus. And it's very, very important to do that. Your listeners need to understand there's about a 10-degree difference, for example, between the mean winter minimum in our campus plots as compared to my home landscape in a rural area southwest of Oxford. Our area is rated as Zone 6a, but there's about a one USDA zone shift, depending on the microclimate that you're growing those plants in. But suffice to say we've actually had more damage to our palms and camellias and banana plants and bamboo from drought conditions and from things that are not at all part of winter cold. Many of the palms... Dr. CATHEY: But traditional gardening always has the feature of dealing with the variants, but our database now is over 100,000 plants have been coded and that the diversity--and most gardeners call the kind of gardening you do an ER gardening, because you're giving much more attention to factors which you perfectly should do if that's what you're interested in. But many gardeners, and I think most gardeners in the United States, they want the toughest plant that they can put because they want it to be there for a hundred years. And the likelihood of the 200 plants that you're growing, they will not get to be 30 years of age. That would be very rare. Dr. FRANCKO: Well, I guess that's wh... Dr. CATHEY: They might make 10. They might make five. But 30 would be very... Dr. FRANCKO: Well, that's what I'm challenging, Marc. I mean, that's why we're taking the approach we're taking, is, you know, one factor, average minimum temperature, is quite important. But as you well know--let's take our particular example so I can quote some data. You know, we are rated as Zone 6a, and, in fact, if you look at the... FLATOW: What would that mean to our listeners? What is Zone 6a? Dr. FRANCKO: Yeah. That's what I was just going to say. Dr. CATHEY: There's no... FLATOW: Where would that run through? That... Dr. CATHEY: There's no longer going to be a 6a in the new map. FLATOW: Well, let's say where it is... Dr. CATHEY: There will be a--that... FLATOW: ...where is it now? It runs right about the middle belt of the country across the country and up through New York? Dr. FRANCKO: Roughly in the middle. FLATOW: Starts like at New York and runs down the middle... Dr. FRANCKO: The point is the running--if you look at the running mean winter minimum temperature in our area, it's somewhere around -8 degrees Fahrenheit. And we have a data set for the last 13 years for both our colder off-campus plots and the plots that are in the warmer part of campus. That particular data set shows the mean as being -6 degrees Fahrenheit. That's still within Zone 6a. It's a little warmer than the running mean. But the variation around that mean is what's critically important here. In that 13-year period, which looks to be a bit warmer than what came before it, the range of winter minimum temperatures is from plus 7 degrees to -24 degrees. The coldest winter temperatures, at least the tie for that, that we've ever had came during the 1994 and '95 winter. So the mean is still 6a... Dr. CATHEY: That's right. Dr. FRANCKO: ...but any plant that survives in our area over that 13 years had to also survive much colder conditions than the 6a mean; in other words, -20... FLATOW: So you could say they can get hit by a pretty good cold spell and still survive. Dr. FRANCKO: Well... Dr. CATHEY: And we've not had a cold spell, where you have the combination of blowing wind, dehydration and frozen roots, and over the last three or four years, we've not had that combination. But the other part with the plants is that with every genus or species, there are plants that are much tougher, as we call it, than others. Dr. FRANCKO: Exactly. Dr. CATHEY: But also, the fact is that if you would do, as many people would do, fertilization and irrigation, drip-dry irrigation and all these things, you would wind up with plants that are much softer. So gardening, what you're dealing with here is a phenomena showing the great adaptability of the plants. But the long term is the chances of them surviving, because the maps that we're dealing with and the coding, that has been going on for something like 70 or 80 years. You realize this is the first such map ever done in the world. The English have duplicated it. The Australians have, but not the Chinese because they just use our codes without doing any maps. So it's just very interesting. FLATOW: I... Dr. CATHEY: But cold hardiness is more than just... FLATOW: I've got to break away. We've got to break away, take a quick break, gentlemen. We'll come back and talk lots more about gardening with Marc Cathey and David Francko. Stay with us. I'm Ira Flatow, and this is TALK OF THE NATION/SCIENCE FRIDAY from NPR News. (Soundbite of music) FLATOW: You're listening to TALK OF THE NATION/SCIENCE FRIDAY. I'm Ira Flatow. We're talking this hour about growing warm-climate plants in the colder climates, more temperate climates up North, with my guests, David Francko, author of the forthcoming book, "Palms Won't Grow Here and Other Myths: Warm-Climate Plants for Cooler Areas," and Marc Cathey, former director of the US National Arboretum and president emeritus of the American Horticultural Society in Alexandria, Virginia. Our number, 1 (800) 989-8255 is our number. Let's see if we can go the phones and get a call or two in this hour, because, of course, lots of gardeners are here. Let's go to Jean in Mesa, Arizona. Hi, Jean. JEAN (Caller): Hi, Ira. FLATOW: Hi there. JEAN: I'm so glad that this show is on. I've wanted for years to tell people about a yucca that we had in Maine, where it's cold. FLATOW: You betcha. JEAN: Way cold. And we moved into a property on a snowy day, and we noticed these white flowers above the snow, and after we were there a couple years, we found out that it was a yucca, and that thing had a stalk on it that would go four feet high with beautiful, beautiful white flowers that dripped in the summer. It stayed out all winter, and the snow would cover it up, and the next summer, there would be baby chutes. The yucca just spread. And now we live in Mesa, Arizona, and I can't get my yucca to flower. FLATOW: Well, some plants need that little cold difference, don't they? I mean... JEAN: Yeah. Dr. FRANCKO: Yeah. And you know... JEAN: Some plants, but not people. FLATOW: Right. Dr. FRANCKO: You know, there are... Dr. CATHEY: We spoke to Jean ...(unintelligible). Dr. FRANCKO: ...that's really interesting... FLATOW: Yeah. Dr. FRANCKO: Go ahead, Marc. FLATOW: David, go ahead first. Then I'll get to Marc. Dr. FRANCKO: Well, I just wanted to comment, because Marc brought up this point and it's important to kind of amplify what she's saying. You know, there are a lot of different species and, even within species, varieties of yucca, and some are truly subtropical or tropical in their distribution and they don't take cold temperatures. But then others, I believe Yucca filamentosa or Yucca glauca, depending on which term you want to use, is one that actually gets well up into Canada, in the central part of the US. It's rated as hardy through Zone 5 and possibly four. And, yes, it's a very, very tough plant and suitable to lots of different kinds of conditions. But it's not the only one. You know, there are... FLATOW: Give us some plants that if you want to try growing in, you know, your back yard now, that would be a good idea to give a shot. Dr. FRANCKO: Well, let's use an example from different kinds of plants. FLATOW: Right. Dr. FRANCKO: If you're interested in growing a palm, for example, Marc's absolutely right. You can't just take any kind of palm that you might see in Florida and expect it to live in Raleigh, North Carolina, or Cleveland, Ohio, or whatever. Some palms are extremely cold hardy. Some are not. Some varieties within a species are more cold hardy than other varieties. And there are even cultivars that have been developed--crepe myrtles, for example--that are more cold tolerant than the normal garden variety plants. FLATOW: So how do we know which ones are good then? Dr. FRANCKO: Well, you can get on the Internet. You can do some research on these. You can read some books. That's kind of one of the reasons for writing the book, actually, is, you know, sorting out some of the things that will work and won't work. Just one example is the Needle Palm--Rapidophyllum hystrix is the scientific name--and I know there's a very large specimen of that in the National Arboretum, just a very, very impressive plant. This palm is well documented to survive at temperatures below 20 degrees Fahrenheit, and in our experience and that of people who've been growing this for 20, 30, 40 years in the Cumberland Plateau and in Kentucky and in Virginia, foliar damage doesn't even begin on this plant until temperatures get down around zero degrees Fahrenheit or below. And, yes, they are affected by cold drying winds, but it's possible to protect the plants with a little wind screen, or what we do on campus is spray the foliage with an anti-transference spray, like Wilt Proof or something like that, and that helps cut down on the desiccation of the leaves. Most of these zones... FLATOW: You talk about bananas growing in Michigan. Dr. FRANCKO: No, they don't... FLATOW: Can you get a banana plant to grow in Michigan? Dr. FRANCKO: Obviously, they're going to freeze over the winter and, in fact... FLATOW: Are they going to die? Dr. FRANCKO: But they won't die... FLATOW: They won't. Dr. FRANCKO: ...as long as you mulch the root zone, because they'll regrow from the root zone. Dr. CATHEY: But the banana takes 15 months or so of continuous growth before it will flower and fruit. That is the traditional hor--and when you have them in the cycles with the low temperature, they never get to fruiting because of the... FLATOW: But you can at least say, `I have a banana plant in my back yard.' Dr. FRANCKO: Yeah. I think that... Dr. CATHEY: But the part is that there are so many plants that do not require being sprayed with anti-transference and all these things, that you don't have to go through all of this. And... FLATOW: Give me a couple. Dr. CATHEY: ...and the garden, you can still have an exotic look, because there are many ways--there are look-alikes all the way through. But the other part about gardening is that, like the crepe myrtle you spoke of, Dr. Egolf at the National Arboretum introduced these florii hybrids, and they have beautiful bark and foliage, yellow in the fall, and then the different colors of flowers. And they will go one zone colder, but if you put them in a container, you can put them out and then move them against the house and you can go even colder areas. But there's lots of things you can do. But the traditional gardening story is that ER gardening is more than most people have the time and the energy to do, and so the tough plants has been the tradition. But, for instance, you go to an English garden, like Christopher Lloyd, which is in southern England, he has a tropical garden that, I mean, Adam and Eve would be at home in. He had everything--but he then moved them into sheds, but he had many of them that were over winter in the southern garden, so... FLATOW: So this is not for the person who wants to set it and forget it. You have to really take care of these gardens and... Dr. CATHEY: You have to do... Dr. FRANCKO: Well... Dr. CATHEY: ...you have to be serious... FLATOW: It's not the low-maintenance gardening people we're talking about here. Dr. CATHEY: No. Dr. FRANCKO: I'd kind of beg to differ with that... FLATOW: OK. Then let's hear about it. Dr. FRANCKO: ...with some plants. Again, it all depends what your goal is and your gardening style and your aptitudes and, as Marc said, what you're interested in putting in. But the Japanese fiber banana, for example, is one I recommend to people in Zone 6 and even Zone 5. That has been grown for many years as a foliage plant. He's absolutely right about that. It's a two-season fruiting plant. But the foliage itself is quite dramatic, and all you have to do is put six or eight inches of mulch over the crown of the plant over the wintertime. That's all you need to do, the same winter protection that you would do with your rose bushes in similar climates. So that I don't think is beyond the scope of what most gardeners would be willing to do. The payoff is that you have this really dramatic plant that comes back every year and it has beautiful foliage. And there are also coming onto the market now one season flowering bananas. The Rajapuri banana is a single season flowering banana. FLATOW: These hybrids or something like that? Dr. FRANCKO: Well, see, the Rajapuri I don't think is a hybrid. It's just a variety of a species that exists out there, and so it is possible. FLATOW: Let me interrupt because we have so little time and so much to talk about. But how much hunting around your property do you need to find a special spot that is either protected from maybe northern wind or has the right kind of exposure? Do you have to identify a good spot for having success with these kinds of plants? Dr. FRANCKO: Well, again, I think Marc kind of hit it right on the head. It kind of depends how far you want to push your limits. I can just give you an example from our home site. We're, again, kind of in a rural area. We get a lot of wind. We don't have any urban heat island effect. I'll put my most tender broadleaf evergreens on the kind of south side of the house so they're out of the wind. But other than that, I've got Needle Palms down near the street, which gets full wind and, you know, fully exposed to the elements and so on. And it just depends on how much you want to push your particular property, and also, what kind of property you have. FLATOW: All right. Let me go to the phones. Let's go now to Raymond in St. Louis. Hi, Raymond. RAYMOND (Caller): Hello. FLATOW: Hi there. RAYMOND: You're welcome. Thank you for having me on. FLATOW: Go right ahead. RAYMOND: Yeah. I had kind of, like, three questions. One is, like, can any of these winter plants grow wild? And if so, what are the dangers of alien plants in different climates? And can you grow cinnamon in St. Louis? FLATOW: OK. What about the whole problem with alien species taking over? Dr. CATHEY: Well... Dr. FRANCKO: Well, that is an excellent question. You want to go ahead on trying that first, Marc? FLATOW: Marc, you want to try that? Dr. CATHEY: Well, the alien plants--the future always is that our gardens and land is already filled with many alien plants, so we'd like not to add any more to the list. But anything that we're talking about that's not flowering, not setting seed and not over wintering will never become evasive. And so many of these--their invasiveness are to hybridize with the natural environment. I don't think there are going to be many other palms for them to mix their pollen up with in the garden, so... Dr. FRANCKO: Yeah, that's an excellent point. And we've actually been investigating that. We have a student that is interested in studying just that point. We have... Dr. CATHEY: Because we're very concerned in corn and soybeans of these genetically engineered new factors or production. So that's not the concern. But the real concern is that I still would like to have a plant that is going to look attractive 12 months of the year if that's what the garden's about. And I would like to not have to do all the intensive things that may be required. That's just my pattern because I have a very busy life. But... FLATOW: But I hear David saying that there are some of these that you don't--that you just have to mulch them over. Maybe they won't be a pretty plant 12 months of the year, you know, but some of them... Dr. CATHEY: Well... FLATOW: ...will have to be with minor care. But you're right, it's very hard... Dr. FRANCKO: Yeah. And... FLATOW: ...to find that combination that's going to be like an evergreen out there that's a semitropical plant. Dr. FRANCKO: Well, it--you know, again, I guess it kind of depends what you define by too much effort, but, you know, we have a fairly large lot at home, and I do a lot of the field work on the campus plots. And really, I don't have that much time, you know, around teaching and doing administration and all that to do that sort of work myself. We are taking a very low-maintenance approach to the work we're doing for exactly that reason. We don't want to put things in plastic lean-tos and artificial heating and that sort of thing because that's not what the average gardener is going to do. They're going to want something that's relatively low-maintenance. And there are many examples that I've found doing traveling for the book where we do have 30- and 40-year-old Needle Palms and Chinese Windmill Palms and Dwarf Palmettos and Monkey Puzzle Trees and so on that are growing in areas that are far colder than the normal zone rating would let you believe. May I just add one other point to that invasive plant issue, though? The other reason that it's unlikely that a palm, for example, would naturalize in areas outside the native range is they grow very slowly from the seed that could be distributed by animals, let's say. There's a very low seedling survival rate and many of the seeds are not even fertile. And it's very unlikely, just due to the life history of these plants, that they're going to take over any areas where they're not extremely well adapted already. You know, they're not naturalizing in areas outside their range. FLATOW: We just have a few minutes left. Marc Cathey, how is the new zone guide that you're working on--how is that going to be different than the old USDA one? Dr. CATHEY: First of all, it will have not only the hardy zones, but the semitropical and tropical zones to be able to deal with this great interest in greater diversity, but also turf and fruit trees, as well as aquatics will be--you'll be able to tell where they will grow. And so we have new significant germ plasm of more hardy or more heat-tolerant plants. We'll have a way to communicate this with the gardening community. But also, gardening has this real exciting thing ahead, is that teaching children to grow food in their gardens, and so we want to find things that will add nutrition and add excitement as well as teach them the geography of the world. So any plant in any garden that can tell a story, I say, welcome to the fold, and let's get up and teach our youth about nutrition and what gardening can do in their home space to provide. So there's nothing more exciting than that. I'm a professional grandfather with four ladies, and I know how much they enjoy all these stories. FLATOW: I'm Ira Flatow and this is TALK OF THE NATION/SCIENCE FRIDAY from NPR News. We're talking with David Francko, author of the forthcoming book "Palms Won't Grow Here and Other Myths: Warm-Climate Plants for Cooler Areas," and Marc Cathey, former director of the US National Arboretum and president emeritus of the American Horticultural Society in Alexandria, Virginia. David, when is your book going to be coming out? Dr. FRANCKO: My understanding is sometime early in February of next year, and I guess if people are interested in looking at it in more detail and possibly doing some advanced ordering, my understanding is you can go to the Timber Press Web site, timberpress.com, and they have a real user-friendly menu for doing advanced ordering and stuff like that. FLATOW: Mm-hmm. Let me see if I can get a quick call in here before we have to go to the break. Let's go to--Is it Tigrad, Oregon, Gretchen? GRETCHEN (Caller): Tigard. FLATOW: Tigard. GRETCHEN: It's a suburb of Portland. FLATOW: I keep thinking of my kids and their Tiggers. Anyway, go ahead. (Soundbite of laughter) GRETCHEN: Well, I wanted to follow up on two issues. One was the issue of, are things changing as time goes by? And secondly, the microclimate issue. I've lived in the Portland area all my life, and we all know the effect of the Columbia Gorge, blows lots of cold air out of the desert in the wintertime. Anyway, but I've noticed that, in theory, our area is indicated to have a low temperature, mean low temperature of between 10 and 20 degrees, according to the official books. And when I was a kid, it did, but I have been watching the weather over the last 20 years, and our mean temperature has basically gone up--it hasn't gotten below 20 in at least 20 years. And I'm now being able to put in plants that I used to see in the Bay Area... FLATOW: Yeah. GRETCHEN: ...and they're doing beautifully and... FLATOW: You're inspiring me because when I used to live in Washington, I used to love--I had camellias, Camellia japonicas, and I used to have a whole garden of them, and I'm now one or two zones above that. GRETCHEN: Ah. FLATOW: And I have a nice southern exposure next to my, you know, brick wall; the sun shines on it. I'm ready now to stick that plant in there if I can find one in my nursery. Now I may have to, like, shop around on the Internet or have them delivered, right? Because these people are not stocking these kinds of plants. Dr. FRANCKO: You know... Dr. CATHEY: Well, the... Dr. FRANCKO: ...they're not doing that ...(unintelligible). GRETCHEN: Hey, we have lots of camellias out here. FLATOW: Yeah. Dr. CATHEY: Well, they're hardy camellias that have been introduced in the Washington area. There's one named for River Farm, there's many of them that our scientist here has been working on. But also, the feature of all this gardening is that we have a new book--AHS has a new book called the "Encyclopedia of Plants and Flowers" that lists 4,250 plants and their coding, and it goes through the fruit, the trees, the vines, the bulbs. And so there is a way to begin and to add new plants to your garden and to be successful. And I don't care whether they're tropical or temperate, we'd like to make sure that they would do well, so bring them in. FLATOW: All right, Gretchen. Dr. FRANCKO: You know, there's... FLATOW: Thanks for calling. Dr. FRANCKO: I'm sorry. GRETCHEN: OK. FLATOW: No, go ahead. I'm sorry to interrupt you. Dr. FRANCKO: Well, I was going to mention if you're a fan of camellias--a lot of folks are--there are a number of new hybrid selections that are on the market now. Now I've not seen them in nurseries in our part of the country, but you can get them by mail order very easily. There's a whole series call... Dr. CATHEY: Well, they're available in the--what are they called? Dr. FRANCKO: Well, there's a whole series called Winter's Star, Winter's Beauty and so on. I believe they're called the Ackerman hybrids and... Dr. CATHEY: And Dr. Ackerman was a breeder at the National Arboretum (unintelligible). Dr. FRANCKO: Right. And those are rated into certainly Zone 6B and we have several on campus that we've had for several years. In fact, one of them is in full flower right now outside Upham Hall here on the Oxford campus, and it does very, very well. And again, you know, we don't baby them. It's just growing in the landscape, so... FLATOW: I love to hear that. Dr. FRANCKO: ...a very beautiful plant. FLATOW: Great to hear that. We're going to take a short pause and come back and talk lots more about maybe new directions in planting that we're all discovering this afternoon, becoming a little more adventurous, putting those Southern plants in our Yankee gardens. So stay with us. We'll be right back. I'm Ira Flatow, and this is TALK OF THE NATION/SCIENCE FRIDAY from NPR News. (Announcements) FLATOW: You're listening to TALK OF THE NATION/SCIENCE FRIDAY. I am Ira Flatow. A brief program note. On Monday's TALK OF THE NATION in this hour, join Neal Conan for a look at Iraq's neighbors, how may they play a role in any war waged against Saddam Hussein? For the rest of the hour, we're going to be continuing talking about the plants and plants that grow in places you don't think they'd continue to grow in, and then we're going to switch gears and talk about the Leonid meteor shower. That's going to be coming up in just a few minutes. Let's finish our conversation about plants. Anything really surprising in your research, David, that you did on this book? Anything that, you know, you really found a surprising plant you would have never have expected to be growing some place? Dr. FRANCKO: That's a really good question. I don't know of any one plant. I think the major surprise has been at the range of different varieties and species of plants within each group that are doing well. I mean, you know, if you have one palm species, let's say, that's hardy in colder areas, well, that's one thing. But if you have 10 or 12 that are doing very well, that's surprising to me because, in some cases, the kinds of information we're getting suggests that they're a zone, zone and a half more fully or hardy than anyone had predicted earlier. So I think it's the variety of plants and also how vigorous they can be after three or four years in the ground that surprises me. FLATOW: Do you think we should just not pay attention to the zone map then, just try some... Dr. FRANCKO: Oh, no, that--it's an excellent guide to get started. I mean, zone maps can tell you what's possible. They can't really tell you what's impossible. But we need guides to talk about expected plant performance, just so long as you don't use them the wrong way and say, `Well, that label says Zone 7 to 9. I'm not even going to try it because I'm in Zone 6.' That's not what you want to do. You know, with the little bit of warming that we're having right now, I get asked all the time `Is that why I see bananas growing on Long Island right now?' And the amount of warming we've had so far is not enough to make the impossible possible. It is enough to suggest that if you want to hedge your bets over the next 10, 15 years and you're putting in a new landscape, you might want to lean towards plants where the zone rating is a bit more towards the warm part rather than the cold part. I mean--but you don't want to throw them out. They're extremely useful. FLATOW: Marc Cathey, last comment about that? Dr. CATHEY: Well, of course, the future is always more wonderful than one could ever imagine because the ability to collect and breed and introduce great diversities of plants has always been the number one priority of horticulturists. So any way to get anybody adding new plants to our environment and getting the satisfaction and getting the beauty and the food that's involved, what more worthy thing can you be. So as they say, know what is the best, because the codes give you your first step in selection, but it's not the only step. And so you have your neighbors and you have wonderful books and, as I say, science to aid you as we move into the 21st century. FLATOW: And thank you very much. Those are the last words, Marc Cathey, former director of the US National Arboretum and president emeritus of the American Horticultural Society. He's in Alexandria, Virginia. David Francko, author of the forthcoming book "Palms Won't Grow Here and Other Myths: Warm-Climate Plants for Cooler Areas" and a professor and chair of the Department of Botany at Miami University in Oxford, Ohio. Gentlemen, thank you both for joining me this hour. Dr. CATHEY: Thank you for... Dr. FRANCKO: Thanks so much, Ira. It's been a pleasure. FLATOW: And have a good growing season. Copyright ©2002 National Public Radio®. All rights reserved. No quotes from the materials contained herein may be used in any media without attribution to National Public Radio. This transcript may not be reproduced in whole or in part without prior written permission. For further information, please contact NPR's Permissions Coordinator at (202) 513-2000. |