A rain garden at the U.S. Botanical Garden.

A rain garden at the U.S. Botanical Garden.

This past winter’s polar vortex was hard on our region’s plants, and gardeners saw even native species die off thanks to cold snaps lasting into spring. Now summer’s heat is already upon us, another challenge for gardeners. With extreme weather becoming the norm, plant enthusiasts have to reconsider what they plant and how they care for a garden. We explore how the urban and suburban gardener can adapt to climate change, and even help offset some of its effects with plant choices.


  • Holly Shimizu Conservation Horticulturalist
  • David Ellis Director of Communications and Editor of The American Gardener, American Horticultural Society

Building A Raingarden At Home

LowImpactDevelopment.org, a Maryland-based resource center, offers a guide for homeowners who want to start a rain garden in their own backyards.

Click through the slideshow for some highlights from the guide.

Plants For Rain Gardens of Every Size

In this document, Low Impact Development outlines the type and number of plants a homeowner would need for their own raingarden.

Plant Lists for Rain Gardens

Communities Rally For Rain Gardens

The Borough of Ambler, Pennsylvania, started an initiative last year that aims to build 100 rain gardens throughout the community in the next 10 years.

Go behind the scenes with organizers in this video from the EPA.

Rain Gardens – Saving Streams One Yard At A Time from GreenTreks Network on Vimeo.


  • 13:06:39

    MR. KOJO NNAMDIFrom WAMU 88.5 at American University in Washington welcome to "The Kojo Nnamdi Show," connecting your neighborhood with the world. If you think this winter's polar vortex was tough on you, try being an azalea shrub or a fruit tree. Many plants didn't make it through the season and now weekend dabblers and serious gardeners have to contend with heavy downpours and summer's heat. Climate change is expected to bring more extreme weather. And some experts say that means extreme gardening, including planting with unpredictable weather in mind.

  • 13:07:20

    MR. KOJO NNAMDIUrban gardeners can even do their part to help offset some of the effects of climate change with rain gardens to absorb runoff and flowers that support endangered pollinators. Joining us to discuss all of this is Holly Shimizu. She is a conservation horticulturist. Until recently she was executive director of the U.S. Botanic Garden. Holly, welcome in your new role, in your new life.

  • 13:07:45

    MS. HOLLY SHIMIZUThank you. Happy to be here.

  • 13:07:47

    NNAMDIDavid Ellis is also in studio with us. He is the director of communications and editor of the American Gardener at the American Horticultural Society. David Ellis, welcome. Thank you for joining us.

  • 13:07:58

    MR. DAVID ELLISThank you. It's a pleasure.

  • 13:07:59

    NNAMDIOf course it's time for your questions or comments, 800-433-8850. Are you a gardener? Has your garden been affected by weather extremes? What would you like to know? Give us a call, 800-433-8850 or send email to kojo@wamu.org. Start with you, Holly, what have you noticed as gardeners when it comes to the weather over the past several years?

  • 13:08:21

    SHIMIZUI have noticed very unusual blooming times. And I have also really noticed the extremes in the weather affecting the garden. And this spring I notice that it came very late. And when it came a lot of things were blooming at the same time. So I think that probably has a very confusing affect on the pollinators who, you know, have this relationship with the plants. And so, you know, is that working or is it off?

  • 13:08:55


  • 13:08:56

    ELLISYeah, I think the -- one of the good examples is humming birds. The humming birds traditionally come early and look for the early blooming vines. And not this winter because of other things related, but the winter before that the humming birds arrived and all of their usual nectar plants had already bloomed. And that was something that's been seen not only in the DC area but in other areas of the country.

  • 13:09:22

    NNAMDIHow'd your plants fare the polar vortex last winter?

  • 13:09:26

    ELLISWell, I almost lost my fig trees, which have been in the garden for at least 20 years. And they're slowly coming back from the roots now but they died almost completely to the ground. Other plants that suffered, rosemary which is always a little temperamental in the DC area, lavender, another Mediterranean type plant has a hard time with winter moisture.

  • 13:09:53

    ELLISWhere I work at River Farm in Alexandria, we had some trouble with our Indian hawthorns which are kind of a borderline plant in the DC area. And they lost all their foliage which is semi-evergreen. So...

  • 13:10:06

    NNAMDIHow about yours, Holly?

  • 13:10:08

    SHIMIZUWell, my camellias did not like this winter. I saw a lot of death and brown. And I saw some plants that rotted from very cold moist soil. And things that were borderline -- I have a hearty ginger which is barely coming up. I have a hearty begonia which is barely showing. So some plants are kind of a lot less stress -- I mean, a lot less strength because of the stress.

  • 13:10:37

    NNAMDIIt seems unpredictability is, well, the norm now.

  • 13:10:41


  • 13:10:41

    NNAMDIWhat does that mean for gardeners?

  • 13:10:43

    SHIMIZUThe unpredictability, I think it means we have to be sensitive to signs and signals and the surrounding environment. We need to find plants that tolerate drought. We need to find -- we need to select good native plants, of course, because they're a little more willing to put up with our extreme weather. But we also really should think about the surrounding environment that we're working within our garden and very much be sensitive to that.

  • 13:11:14

    NNAMDIYou made the point that gardeners have not focused on climate change but they could be leaders on this.

  • 13:11:19

    SHIMIZUI believe that because if you look at gardeners and if you think about all of the gardening effort we have, if you put it together collectively, would you see a change? Absolutely because we have now -- I think we're now seeing that people have a greater interest and a recognition that gardeners can be stewards. And that's what this is all about.

  • 13:11:46

    NNAMDIHow are you dealing with these extremes in your gardening choices?

  • 13:11:50

    SHIMIZUSo I'm looking for plants that will go a zone up. That means something hotter and warmer and that will go a zone down that will take colder and that will be flexible in terms of how they thrive. And I'm also trying to create gardens that are more diverse and...

  • 13:12:12


  • 13:12:12

    ELLISAnd one of the things that we're hearing is, you know, the native plants adapted to be in this region, which has experienced, you know, climate change before. So they have an historical adaptability to extremes of climate. And that's one of the reasons why natives are often a good choice for gardens. So that, I think, is an important thing to consider.

  • 13:12:34

    NNAMDIDavid Ellis is director of communications and editor of the American Gardener at the American Horticultural Society. He joins us in studio to discuss climate change and gardening with Holly Shimizu, conservation horticulturist, until recently, executive director of the U.S. Botanic Garden. You can join the conversation by calling 800-433-8850. Do you plant native species in your garden? Why or why not, 800-433-8850? You can send email to kojo@wamu.org. Are there microclimates in our region? And if so, what does that mean for our gardeners?

  • 13:13:10

    ELLISYes. There're always microclimates in almost any garden. Especially in the city, in D.C. itself, obviously the urban heat island effect, just being warmer with all the hard surface and permeable surfaces helps create a zone warmer than probably the Maryland suburbs where I live. So you can grow things like figs and some of the other fruiting plants quite well. A southerly exposure is always a good microclimate because usually that's where you get more sunshine, more warmth for the plants. Planting figs against the southern wall is always very advisable and when we didn't have such warm temperatures.

  • 13:13:53


  • 13:13:53

    SHIMIZUYes. I notice microclimates in my own garden where it's very cold. And for example, after the snow I can see where the snow's not melting and I know that's really cold. And then I have the really hot spots and then I have the really wet spots. And I really pay a lot of attention to water. And I think that's something we must focus on a lot.

  • 13:14:13

    SHIMIZUWhere does the water go when it rains and where does it sit after the rain? So if you want to make a rain garden, which is a great thing, you want to know all about how the water is traveling through your garden during and after a heavy rain.

  • 13:14:29

    NNAMDIDavid, am I imagining this or are weeds out of control these days?

  • 13:14:34

    ELLISYeah, and one of the research that we've seen is that in an atmosphere with higher carbon dioxide, some of the especially vines like poison ivy, kudzu, English ivy and porcelain berry tend to thrive. And I think we're going to see a lot more of these invasive weeds. And we'll need to be finding ways to get them out of our landscapes and our wild areas.

  • 13:14:58

    NNAMDIOn to the telephones. We'll start with Pat in Laurel, Md. Pat, you're on the air. Go ahead, please.

  • 13:15:05

    PATYes, good afternoon. I've been involved with azaleas at the Brighton Dam Garden since 1950s long before there was global climate and warm changing. And we've had every conceivable kind of extreme weather and the azaleas have always handed it. Not seeing any difference between 50 years ago and now.

  • 13:15:28

    NNAMDIIn terms of -- you've seen no difference at all?

  • 13:15:31

    PATNo, sir. I mean, we've had floods. We had the blizzard of '66. We've had droughts. We've had every kind of weather. We're right next to a dam. Everyone knows what happens with the weather and no problems with -- before or after there was global climate and warming change.

  • 13:15:48

    NNAMDIHolly, what do you say to that?

  • 13:15:49

    SHIMIZUWell, then you've got some good azaleas probably. And, you know, the -- I love azaleas and they do tend to be good plants for Washington gardens, no doubt about it. What kind do you have? Do you have natives, do you have hybrids? What do you focus on?

  • 13:16:04

    NNAMDIOh, I think Pat's call dropped off.

  • 13:16:04

    SHIMIZUOh, did he go? Okay.

  • 13:16:06

    NNAMDIYes, I'm sorry.

  • 13:16:07

    SHIMIZUWell, nonetheless, I mean, when we think of Washington gardens, we think of azaleas, don't we? I mean, they do well. Go to the National Arboretum when the azaleas are in bloom. It's a traffic jam but it should be. They're fabulous.

  • 13:16:19

    NNAMDIThe past few weeks have also brought unusually heavy rains. What does that mean for a yard garden?

  • 13:16:28

    ELLISWell, most of our plants are adapted to, you know, rain in the springtime. So for the most part they're going to handle it pretty well. Again, some of the ones that are Mediterranean plants and don't like to have moisture around their -- the point where the crown is at the top of the soil, you may see some problems with that. But otherwise it's been okay other than runoff into our storm sewers.

  • 13:16:52

    NNAMDIHolly, you say these weather extremes may mean that we may have to change our expectations. Can you talk about how that relates, for example, to our lawns?

  • 13:17:02

    SHIMIZUOh yes. I have a lawn but my lawn -- I call it the green carpet because it's a mixture of whatever wants to grow there. I have clover and, you know, some of the plants you might think of as weeds. But I mow it and it looks great. And why do I have that? Because having a perfect lawn in this region really doesn't work for the most part unless you use a lot of toxic chemicals. And I'm not interested or willing to do that. So I think the green carpet works.

  • 13:17:34

    NNAMDIDavid, how should we be thinking differently about our yards and gardens?

  • 13:17:39

    ELLISWell, what we like to promote through the American Horticultural Society is for people to view their garden as their connection to the earth, to sort of look at it as your own little world that you can take care of and be a steward of, but also kind of fosters a better connection for people with the earth and with growing plants.

  • 13:17:59

    ELLISSo what you can do is you treat your own piece of property like you would, you know, the world around you. Treat it well and I think that's a good way to think about it.

  • 13:18:09

    NNAMDIHere is Eric in Germantown, Md. Eric, you're on the air. Go ahead, please.

  • 13:18:14

    ERICYes, hello. This is Eric Winger calling. I want to say hi to Holly and to Dave Ellis.

  • 13:18:19

    SHIMIZUHi, Eric.

  • 13:18:20

    ELLISHi, Eric.

  • 13:18:22

    ERICEnjoying the show. I want to make a comment about the native plants. And of course we do recommend, you know, native plants wherever possible. One of the big impacts that we're finding are that the deer have also adapted for the native plant and they tend to do quite a bit of damage to the native plant. And so when we put them in, we often don't find them there after a really bad winter such as the one we just went through.

  • 13:18:47

    ERICSo sometimes the native plant is great, especially if it has protection. But sometimes we need to look at other plants that might benefit the native fauna as well. I wanted to get your comment on that.

  • 13:19:01

    SHIMIZUOkay. Good point. Well, one thing I know that when deer are hungry they'll eat just about anything. But they aren't as inclined to eat the things that are really pungent, things like, you know, a lot of the strong herbs like oreganos and rosemaries. But in my opinion, what works best against deer is a deer fence. And you can get them. They're not that expensive. They work. And then you can have the garden of your dreams.

  • 13:19:29

    ELLISYeah, I think, you know, especially things like vegetables, you know, you have to have a fence around now because the deer just look at it as a salad bar. But the deer do eat a lot of natives, but they eat a lot of non-natives too. So really it's not looking at either of those for deer. It's just looking at the ones that resist deer like hellebores for instance.

  • 13:19:49

    NNAMDIEric, thank you very much for your call. Onto John in Adelphi, Md. John, your turn.

  • 13:19:55

    JOHNYes. I have a house that's kind of on the side of a hill. And there are a lot of big mature oak trees, but also a lot of English ivy. And I, you know, keep pulling the ivy out and off the trees. And, you know, for one, I'm a little reluctant to pull it all out because it kind of cuts down on erosion. And I was wondering what -- you know, to the extent that I'm successful in getting rid of it, what should I put in as a substitute for, you know, holding the hill on the side so my house doesn't slide down the hill?

  • 13:20:27


  • 13:20:28

    ELLISWell, there's a number of other groundcovers you can try. I mean, it is hard to contain English ivy. You know, you just -- it'll go up trees as soon as it can. One is the liriope. Lilly turf is a good -- it's a -- has a strong root system. It's good in shade and will help on a hill. You could also look at pachysandra, either the Japanese pachysandra or the native pachysandra. Those are both good choices. Maybe Holly has a thought too.

  • 13:20:56

    SHIMIZUYes. Well, I have banned English ivy from my garden. I detest it. I'll go so far as to say I hate that plant because...

  • 13:21:04

    NNAMDII get the impression she doesn't like it.

  • 13:21:07

    SHIMIZUIt's killing the trees. I live in Glen Echo along the Potomac River. It's killing the trees. So nonetheless I have removed all of it. And I'm using a variety of things to hold the soil on slopes like sedges, native grasses. I really like those. Some of the Carrick species are awesome. Some andropogans. I would just put in the things that do well. One of my mottos now, because I'm a much less uptight gardener, is I grow what grows well for me. And also is not going to be invasive and take over. So those are a couple of my rules.

  • 13:21:44

    NNAMDIThank you very much for your call, John. Good luck to you. We've got to take a short break. But when we come back, we'll continue this conversation on climate change and gardening and take your calls at 800-433-8850. How did your yard fare over the harsh winter? Need any advice, 800-433-8850? You can send email to kojo@wamu.org. Send us a tweet @kojoshow. I'm Kojo Nnamdi.

  • 13:23:54

    NNAMDIWelcome back. Holly Shimizu is with us. She's a conservation horticulturist, until recently executive director at the U.S. Botanic Garden. We're talking climate change and gardening with David Ellis. He is director of communications and editor of the American Gardener at the American Horticultural Society. And taking your calls at 800-433-8850. If the lines are busy, shoot us an email at kojo@wamu.org. You both consider water conservation important. How can a gardener conserve water and still have a beautiful garden, David?

  • 13:24:26

    ELLISThere's a number of approaches to this. One -- obviously one is selecting plants that don't need as much water, drought-tolerant plants. They're quite easy to find now. Obviously western gardeners have really moved in this direction out of necessity. We can do that. Other approaches include using drip irrigation or soaker hoses instead of trying to water everything by hand or using sprinklers. They are much -- drip irrigation and soaker hoses use a lot less water. So prevent -- and reduces evaporation.

  • 13:25:03

    ELLISMulching the plants, using mulch helps to reduce the water loss. It also insulates the plants from extremes of heat and cold so helps keep the roots healthy. Rain gardens, which we had talked about earlier, is another good way because you can -- you keep the water that's running off your house in your own garden and use it to keep plants that like a lot of water moist.

  • 13:25:28

    NNAMDIHolly, tell us exactly what is a rain garden or rainscape, and how do they work?

  • 13:25:34

    SHIMIZUWell, so this is a really great way to garden now. And it is -- what it means is keeping the water on site. And what you want to do with water is you want to slow it down. You want to spread it out because the goal is to let it permeate down. Don't let it be treated like a waste product and go off in the sewer drains because you're losing this precious resource.

  • 13:26:00

    SHIMIZUAnd, you know, one thing that I like people to know about what happens when you have trees along water bodies, rivers, creeks, lakes. They will clean the water as it's permeating down into the water body, the soil roots -- the soil, the plant roots. So we really need to use all the water that we have and not let it be taken away. So there's some great places where you can get information on how to make one. I couldn't probably explain it in any clarity to you.

  • 13:26:35

    NNAMDIOne of those places is at our website kojoshow.org where you'll also find all kinds of -- a list of good green garden plants. Kojoshow.org is the website. But, David, it's not that difficult to create a rainscape. Can you give us some basic advice as to how to choose a site and create one?

  • 13:26:57

    ELLISWell, you're usually looking for a sloping site where you already know the water is running off. You know, you can just -- if you have the guts, go out there in a rainstorm with an umbrella and watch where the water in your garden is flowing, where your gutters are going. Some people run those gutters underground and use a French drain system. Essentially a rain garden is sort of an extensions of a French drain system where you run the water into -- slow it down and run it into an area where it'll sink in and stay there for a while until it either runs off or is absorbed by the plants.

  • 13:27:31

    NNAMDIAnd, as I said, you can go to our website and you will see a list of good rain garden plants there. We move on now to Kathryn in Alexandria, Va. Kathryn, you're on the air. Go ahead, please.

  • 13:27:42

    KATHRYNHi. Thank you very much. Number one, Holly's husband did my garden. Number two, I live across the road from River Farm American Horticultural. And they're both fantastic.

  • 13:27:53

    SHIMIZUWow, thank you.

  • 13:27:54

    KATHRYNYou're welcome. I recently took out my front yard grass about three years ago and planted a wild flower meadow. My neighbors love it. The birds and the bees and everything love it. but this year -- and I think it's the weather -- we've had a bumper crop of fleabane. And I am worried that it is going to push out all the natives I put in in my meadow. Is there any suggestion?

  • 13:28:19

    SHIMIZUYes. I am not a fan of fleabane, even though it's native. I admit that. And the reason is that as you know, Kathryn, it takes over when it seeds. Do not let it set seed. Cut back the flowers. You can stop it if you don't allow it to seed. And that's what you should do ASAP.

  • 13:28:40

    KATHRYNI'm trying to dig and pull the roots out as well. Is that how it goes?

  • 13:28:43

    SHIMIZUThat's better too. That's even better if you're willing to do that.

  • 13:28:48

    KATHRYNOkay. All right. I think the birds brought it in. I did not plant it.

  • 13:28:51


  • 13:28:52

    ELLISWell, one of the things about a wildflower meadow is that it always needs editing. So this is where you can edit out the bad and add in new things. It'll help to make it more diverse.

  • 13:29:03

    SHIMIZUI hope people will be inspired by your meadow.

  • 13:29:06

    KATHRYNWell, my neighbors certainly are. They love it. And when I do edit, I give them plants and they're all putting them in. So that's kind of exciting. Thank you.

  • 13:29:14

    NNAMDIKathryn, thank you so much for your call. Good luck to you. We got a number of emails and Tweets about fig trees. I'll just read the longest one. It says, from Carrie Sue, "Help. Our large mature fig tree at least a decade old, 25' tall has yet to wake up from its winter dormancy. It's still completely bare save for a few sprouts on the trunk and one or two lone small leaves high up in the tree. I tested the bark and it's still green underneath but otherwise it looks dead. Will it bloom this season?" I don't expect figs, but might we get shade leaves? Must it be cut down or cut back?

  • 13:29:49

    SHIMIZUI would recommend cutting back the dead part of it. And I'm sure that the tips are dead. And I have noticed that some of the figs are sending up leaves from the base. So allow for that to happen. Once you're able to determine the dead growth, remove it and see what happens. I think a number of them will come back. Some of them may be too far gone.

  • 13:30:11

    ELLISYeah, I think it's going to be kind of hit or miss who loses theirs and who doesn't. But I wouldn’t give up on it yet. I'd give it a little while longer. And as Holly said, cut back the dead parts.

  • 13:30:22

    NNAMDIAnother effect of climate change, David, is being felt by pollinators. Can you talk about what creatures are important to the lifecycle of plants and what they're facing?

  • 13:30:31

    ELLISWell, a garden -- each of our gardens is an ecosystem of sorts. And we're all sort of responsible for the greater ecosystem around us. The plants and animals have evolved, you know, together. And especially if you're growing a lot of natives, you know that the insects and the birds that come in are ones that rely on those for nectar and for food. One of the things that we're seeing through research is that some of these critical pollinators are disappearing or becoming endangered.

  • 13:31:04

    ELLISWe recently ran an article about monarch butterflies which everyone knows they kind of -- the mega fauna of the insect world. And they have been suffering tremendous losses over the last five or ten years partly through habitat loss, partly through modern agriculture practices. And one of the ways gardeners can help these insects and others is to plant a diverse selection of plants, plants with different kinds of flowers, plants that bloom at different times of the year. For monarchs in particular they use milkweeds as their larval host plant, so plant some milkweeds in your garden.

  • 13:31:47

    NNAMDISuggestions, Holly?

  • 13:31:48

    SHIMIZUWell, yes. I'm planting a few different species of milkweeds and I'm also planting for a long season so that my spring begins in February and then my growing season goes into December. So I have a short time of dormancy because I garden for pollinators. So there's always something happening. And in addition to that, I'm more thoughtful about not having so many double flowers because I want flowers that the insects and pollinators have access to. I even plant for bats because bats are very important pollinators. And I do that on my roof garden.

  • 13:32:29

    NNAMDIAnd so diversity is...

  • 13:32:31

    SHIMIZUDiversity is extremely important.

  • 13:32:34

    NNAMDIOn now to Laura in Greenbelt, Md. Laura, you're on the air. Go ahead, please.

  • 13:32:40

    LAURAHello. Thank you very much for taking my call. Since you're discussing pollinators, I was wondering if you might discuss some more specific plants in Greenbelt, Md. and also in Monterey, Calif. where in Pacific Grove right next door we have the monarch capital of the world. So besides milkweeds, is there anything else we can do to help the monarchs?

  • 13:33:04

    ELLISA lot of plants for monarchs, tithonia which is a Mexican sunflower is a good nectar plant. They will use nectar from a lot of flowering plants so you can use both natives and non-natives for monarchs. We're going to provide a link to the article which will allow you to look at that and get some ideas for other plants as well. Holly, do you have thoughts?

  • 13:33:31

    SHIMIZUOh, I do. I love planting Echinaceas, the coneflowers and I like planting native species of rudbeckias. I like to plant plants in the carrot family, those things like parsley. And caterpillars are really fond of plants in that family. They love a lot of the fennels. And so I really specifically plant those to get a broad range of pollinators.

  • 13:34:01

    LAURAFantastic. Thank you so much.

  • 13:34:03

    NNAMDILaura, thank you very much for your call. A lot of people assume native plants are the best choice for any given region or climate. Is that always necessarily the case, David?

  • 13:34:13

    ELLISWell, obviously when you're talking regional you want to look at your regional native plants. It's not as if natives are native throughout the country. With a few exceptions there are a few broadly native plants. In most cases, you know, from what we can tell, native plants are the best choices for gardens. But that doesn't mean you should use them exclusively. There's plenty of lovely non-native plants. I'm not against non-native plants. I grow many in my garden including hellebores which are beautiful spring-blooming perennials. But I do like to base my garden around natives and use a lot of diverse natives that are all from this region.

  • 13:34:53


  • 13:34:54

    SHIMIZUWell, one of the people that I really love is a man named Dr. Doug Tallamy. And he came out with a new book, which Davis will mention. But he teaches us about native plants and how they have co-evolved with their pollinators. And so if you were to make one choice of a native, plant a native oak, for example, in this area maybe a white oak because it provides and is home to so many insects which provide food for birds and other pollinators. And so you're really adding, you're really giving something by making that choice.

  • 13:35:31

    ELLISYeah, an oak tree can create -- basically it's, you know -- be a major part of your own little ecosystem. The book that Holly mentioned is called "The Living Landscape: Designing For Beauty and Biodiversity in the Home Garden." It's by Doug Tallamy and Rick Darke. It's just come out and I think it's going to be a super book for anyone who's starting a garden or trying to redesign their garden. It's very informative.

  • 13:35:54

    NNAMDIAnd speaking about native plants, we have Sid in Washington, D.C. with some advice and maybe a warning. Sid, you're on the air. Go ahead, please.

  • 13:36:04

    SIDHi. Thanks, Kojo. Yeah, I've started up a business called Capitol Creations a few years ago. I live on Capitol Hill and I garden around the Hill. And these are very small postage stamp-size yards. And a lot of the people have done away with their green grass turf lawns in part because it reduces the storm water pollution runoff. And so when-- oh, what I've noticed is when one neighbor has their yard converted over to native grasses and plants then the other neighbors follow suit, so sort of an interesting social phenomenon.

  • 13:36:39

    SIDBut what I recently learned is that you have to be careful about not only not using the pesticides, the neonicotinoids which are nicknamed neonics for short. Not only not using those because they kill off the bees, but also not buying plants that have been treated with those pesticides, plants that you might buy from the Home Depot or the Lowe's, because those also are not good for the bee population. And maybe our guests can elaborate a little bit more on that.

  • 13:37:15


  • 13:37:15

    ELLISYeah, I'm glad you brought that up. We were going to talk about that. I think, yeah, clearly it's very important if you want to attract pollinators. And we need to attract pollinators because they're struggling with the economy collapse disorder effecting honeybees and many of the other native bees also struggling, in addition to the monarch issue we mentioned before. So don't use pesticides. Don't use synthetic pesticides in your garden. There's lots of ways to help your plants and keep them healthy without using chemical pesticides.

  • 13:37:50

    ELLISThe neonicotinoids that were mentioned have been implicated in a lot of these pollinator and the bee declines. It's difficult to find plants that have been raised without these chemicals being used. It's difficult to identify them. So growing your own is a key thing to do. Just grow from seed or get them from friends who can pass along treasured plants to you.

  • 13:38:17


  • 13:38:18

    SHIMIZUAlso there's some really great plant sales through the Native Plant Society. I'm a member of the Maryland Native Plant Society, the Virginia Native Plant Society, our public gardens, like Green Spring in Virginia and the National Arboretum. They have great plants for sale. And the other thing is to really support your small garden center because there you have a much better possibility of getting plants that are well grown and healthy.

  • 13:38:44

    SHIMIZUI also like to use organic fertilizers. And I think that we can say, with confidence, that a home gardener really does not need to use any toxic chemicals. It's just not necessary. And I allow plants to die. I say, you know, they have lifecycles. And maybe they just don't like it here. And so I'll try something else.

  • 13:39:07

    NNAMDIThank you so very much for your call, Sid. We move on now to Dorothea in Washington, D.C. Dorothea, you're on the air. Go ahead, please.

  • 13:39:16

    DOROTHEAThank you, Kojo. This is a wonderful program. I wanted to talk about small gardens. I'm in Georgetown. I have an ordinary size garden and I've had it for 50 years with normal things. And all of a sudden my niece started me on -- last year on natives. I have put in Echinacea, ginger, salvia. I started mixing my grasses and let clover grow. And this year all of those natives just looked wonderful. And my other flowers did not do as well.

  • 13:39:48

    DOROTHEASo the thing that I really would like to see if we could have a movement going of people with small gardens in cities to start this thing of using natives. I'm going to study much more. I just put in my first milkweed and I'm so thrilled. I've seen a butterfly. I've seen bees come in. And even the birds, they love to dig around in my grass, because I have only a mixture there, and they find worms.

  • 13:40:16

    DOROTHEAAnd the thing is that I think a little bit each one of us can do, can help a big environmental problem. And I'm very thankful for this program. Thank you so much.

  • 13:40:28

    NNAMDIDorothea, thank you so much for your call. We got a call from someone who couldn't stay on the line who wanted to know where to get milkweed seeds. Holly?

  • 13:40:36

    SHIMIZUWell, they're easy enough to get. And I'm trying to think where I've gotten them from -- exchanges.

  • 13:40:42

    ELLISYeah, the seed exchanges. You can also get milkweed plants in many cases. You can buy them from seed. There's a couple of great nurseries in the Midwest. One's called Prairie Nursery and one's called Prairie Moon Nursery. And I believe both of those nurseries will have milkweeds. And they're very organic. You'll get good plants or seeds from them. I'm sure you can find them locally as well. At least butterfly weed is probably the...

  • 13:41:08


  • 13:41:09

    DOROTHEAAnd Dorothea, if you're looking for a list of native species, you can find some of Holly's favorite at our website, kojoshow.org. Holly, what are some of your favorite plants and seeds in that category?

  • 13:41:23

    SHIMIZUOh, that -- just favorite natives?

  • 13:41:25


  • 13:41:25

    SHIMIZUOh, I love the fringe tree. I just happened to see one in bloom and this fragrance was just overwhelming. And I had a wonderful visit at the Adkins Arboretum in Denton, Md. It's all native plants. And that's where I bought a lot of the native azaleas, which I absolutely love. I particularly love native trees -- black gums, those are stunning. And they have, you know, just such gorgeous year-round qualities. I love redbuds. I like plants so much that that's a dangerous question. When you ask Holly her favorites, she goes on and writes a book.

  • 13:42:01

    NNAMDIWhich is why we're going to take a break right now. And when we come back, Holly, we'll have recovered from this question and we'll move on to other issues. But you can still call us at 800-433-8850. How'd your yard fare over the harsh winter? Are you a gardener? How has your garden been affected by weather extremes? You can also send email to kojo@wamu.org. I'm Kojo Nnamdi.

  • 13:44:21

    NNAMDIWe're discussing climate change and gardening with David Ellis. He is director of communications and editor of The American Gardener at the American Horticultural Society. Holly Shimizu is a conversation horticulturalist, until recently, executive director of the U.S. Botanic Garden. David, you, it's my understanding, have a prairie garden at home, not native at all. Why did you decide to do that?

  • 13:44:45

    ELLISWell, it is native. Some of the plants are a little more native to the Midwest. But they're -- a lot of them have the range that they reach the East Coast as well. I grow a lot of native grasses. Switchgrass, with is panicum virgatum, which is native in this region as well as the Midwest. But I picked the prairie wildflower probably because they adapt well to clay soils. And that's what I have in my Silver Spring garden. So they throw deep tap roots and they do really well in the clay. And they also attract a lot of pollinators and other wildlife.

  • 13:45:21

    NNAMDIHolly, we got an email from Sherry in Fairfax. What about home-grown vegetables? Do tomatoes and corn have a chance to thrive this summer? What vegetables will grow well in this cooler weather and wet ground?

  • 13:45:33

    SHIMIZUWell, that's a great question. The tomatoes, they like heat. They like sun and heat. And so I think that we're okay to plant them now and they will get established. But don't try to grow them in the shade. Try to grow them in hot sun and don't overwater them. That's what I recommend with tomatoes. And the second thing she mentioned, corn -- only grow corn if you have a lot of space. I mean corn's not so much for the city gardener at all. But other vegetables that I like to grow are peppers and hot peppers. I like to grow squash. And if I have a giant place where I can grow them on a compost pile, I grow watermelon and pumpkins.

  • 13:46:17

    NNAMDIHere is Ellen in Leesburg, Va. Ellen, your turn.

  • 13:46:22

    ELLENThank you. I focus on native plants in my garden, but I draw the line at poison ivy. And since I know poison ivy provides important winter forage to birds, I was wondering what other native plant I could plant in the same space that would provide the same food source.

  • 13:46:42


  • 13:46:44

    ELLISThere are some vines. I'm trying to think. Trumpet creeper?

  • 13:46:48

    SHIMIZUYeah, or crossvine.

  • 13:46:50

    ELLISCrossvine, bignonia is one.

  • 13:46:52

    SHIMIZUCapreolata is a great one.

  • 13:46:53


  • 13:46:54

    SHIMIZUYeah. And then other native vines that I would recommend, I like gelsemium. That's a beautiful evergreen vine that does very well. And -- I'm not saying it'll give the exact same food as the poison ivy. But there's a lot of poison ivy in nature. And so probably you don't need to worry so much about that.

  • 13:47:17


  • 13:47:17


  • 13:47:18

    ELLISVirginia creeper, you know, is also a bit weedy. But it's probably not as bad as poison ivy. And it does have, I think, fairly similar associations for the fruits.

  • 13:47:28

    NNAMDIEllen, thank you very much for your call and good luck to you. We got an email from Angela in Silver Spring. "My neighbors planted bamboo years ago, and now it's creeping into my yard. I hate it. Short of agent orange, how do I prevent it from coming into my yard?"

  • 13:47:45

    SHIMIZUI like to mow it. And that will stop it. And/or put in a barrier. I speak from experience, because my neighborhood has so many bamboo wars. And so I've tried to advise people, if they're going to plant it near your neighbor's yard, to make sure that they have a deep and strong blockage. What do you think?

  • 13:48:06

    ELLISYeah, I have the same thing going on in my garden. And I have been cutting them back and mowing them. I also eat them once in a while. I eat the new stems coming up. I don't know that it's truly a great food but it's worth a munch once in a while. I think the barrier is about the only way to go to really permanently kind of treat -- because they can send roots as deep as three feet below the surface, so difficult to eradicate.

  • 13:48:33

    NNAMDIDonna, in Bethesda, Md. Hi, Donna.

  • 13:48:36

    DONNAYes, hi. First of all, I'd like to say thanks to Holly for saying it's okay to let your plants die if they wish. That was really an aha moment for me.

  • 13:48:43

    SHIMIZUThank you. I believe it.

  • 13:48:46

    DONNAWell, thank you. You've made my day with that. Well, my hydrangeas have been doing well for about 20 years. But this year, the long branches that are mostly -- are still mostly bare, and the new leaves are growing out at the base, like our fig trees. And I'd like to know, why is this happening? And should I cut them all down to where the new leaves are growing?

  • 13:49:05

    ELLISYes, you should. And it's the cold weather again. It's the, you know, hydrangeas tend to throw out all those little branches. And when they get the cold winter like that, it just kills them back to the ground essentially. So cut all those -- right now, that you can see where the new shoots are coming out, cut them back to the nearest shoots and then let them grow up from there. It may take them a year to fully recover. But they'll be back to their own full blooming by next year for sure.

  • 13:49:32

    DONNAOh, that's good news. Thank you.

  • 13:49:33

    ELLISYou're welcome.

  • 13:49:34

    NNAMDIThank you for your call, Donna. You, too, can call us at 800-433-8850. Or send email to kojo@wamu.org. We're talking about climate change and gardening. Holly, you say gardeners need to think about how their garden connects with the surrounding environment. What do you mean by that?

  • 13:49:52

    SHIMIZUWell, I look at the way we're gardening and as a way to really make a connection with our region. And so I think that we are a part of the greater ecosystem. So our garden is something that gives us joy and pleasure. But it also is something that if we think about the green corridors, for example, that would be green connectors for wildlife -- our gardens can integrate in with that. And I think that, that then is something greater that we're doing, in addition to creating a space for our own enjoyment.

  • 13:50:28

    SHIMIZUIn fact I tell people to not use this term which I learned in college years ago, ornamental horticulture. Plants are much more than that -- than just ornament. That's one little thing. They're so much bigger and greater. And I think that being a part of the greater ecosystem makes gardening that much more rewarding.

  • 13:50:49

    NNAMDIWhen you say they're much more than that, you note that a lot of our plants were originally medicine and food and still play that role.

  • 13:50:57

    SHIMIZUThat's exactly right. And I love to teach people about that, you know, and fibers. And I love to focus on how these plants have been absolutely essential to human lives and to the environment.

  • 13:51:11

    NNAMDIYou know, David mentioned earlier a salad bar. And John, I think, in Bethesda, Md., may be having some problems with that salad bar. John, you're on the air. Go ahead, please.

  • 13:51:21

    JOHNHey, Kojo. What a great show on a rainy, rainy Thursday. Wow, this is a great topic. Thank you.

  • 13:51:28

    NNAMDIYour question, John?

  • 13:51:31

    JOHNI'd like to ask you, you know, I've been taking notes about the rain garden and about the pollinators. You know, I'd love to go back and fill my back yard with all this, but deer. What of these are going to survive deer in my back yard?

  • 13:51:45

    NNAMDIYou mean you don't want to prepare a salad bar for deer?

  • 13:51:50

    JOHNNo, that's an expensive salad bar I'd like to save for myself.

  • 13:51:53

    NNAMDIHere's David.

  • 13:51:54

    ELLISWell, John, how big is your garden?

  • 13:51:58

    JOHNI've got about a quarter acre that deer can get to. And I've got a private upper level that they can't get to. So it would be nice to use that quarter acre down there. Again, I've got some runoff. I've also got a great place for pollinators and anything else to add to it. But the deer come through and it's just really, really chewed down everything.

  • 13:52:20

    ELLISYeah, the deer have certainly become one of the biggest challenges to suburban and urban gardening in the D.C. area. Really, as Holly said earlier, a fence -- an exclusion fence is the only foolproof method. There are some, you know, fences you can find now that are kind of a mesh that's not as unsightly as, you know, some of the fences and a little cheaper than installing a complete fence. The other thing to do is, you know, plant a mixture of things that they will eat and things they won't. That requires some research in finding out what's -- what they won't eat and some trial and error.

  • 13:53:01

    ELLISI wish I could give you a complete thing. The sprays will help a little bit, but they're -- they definitely don't work for the long-term solution.

  • 13:53:09


  • 13:53:10

    SHIMIZUWell, I would recommend -- there is a kind of fence, John, that you can buy that is not that expensive and it's black. It's a black plastic. And it's not expensive. And it hides in the landscape. And so the part of your garden where you want to really garden, I really would encourage you to do that. And you won't notice it that much. And it really will enable you to have a reliable garden. There are some good websites for deer-proof plants -- now, if there is such a thing, because I'm not going to be fully confident about that. But Rutgers University does have a website which does focus a lot on plants that deer don't like as much.

  • 13:53:54

    NNAMDIAnd, John, thank you very much for your call. Good luck to you. We got an email from Courtney who says, "Any idea on how to keep bugs and pests from my vegetables without pesticides?" David?

  • 13:54:06

    ELLISWell, obviously it's going to depend on which ones. Slugs tend to be one of the biggest pests in vegetable gardens. There's a number of approaches to those. Diatomaceous earth is one. There are a number of less-toxic approaches. Sluggo is one. It's an iron-oxide compound, I believe. There's also, you can get copper barriers that will help. So -- also keeping mulch out of your garden, because slugs hide under mulch. The old beer traps are, you know, effective, but they won't be 100 percent.

  • 13:54:47

    ELLISFor other things, you know, we preach planting plants that will attract beneficial insects. Holly mentioned fennel earlier, dill. These will bring in beneficial insects and help to control some of the pests. But when you get down to specific ones for specific vegetables, there's a lot of -- it would take all day to give you all of the advice you need.

  • 13:55:09

    NNAMDIGo ahead, Holly.

  • 13:55:10

    SHIMIZUOne thing I'd mention about that is that plants have their season. They have their highlight. So say, for example, I grow squash. And it does really well and it produces a lot. And then by July it gets these horrible slugs and -- they're not slugs, they're a little rot at the base from insects chewing it. And I just then rip the plants out and start over with something else. So it's okay. I don't spray it -- I would not spray it. You don't need to. So let the plant do its thing. And when it's not happy, get rid of it.

  • 13:55:45

    NNAMDIMacarena in Leesburg, Va. Macarena, you're on the air. Go ahead, please.

  • 13:55:51

    MACARENAHi. Thank you, Kojo. I love your show. I wanted to ask a question. I recently bought a new home in Leesburg. We have three-quarter acre land. And the reason we bought is because I wanted to fulfill my dream of having a beautiful garden. And I'm finding out that it's a lot difficult that I thought. It's a huge investment. And when I go to the different nurseries, they're willing to sell me anything I want, which is very dangerous because I don't get any device, even from the designers, as far as how to put the right things in my garden, taking into account all the things that you mention, such as water, sunlight, wind...

  • 13:56:33

    NNAMDISo you need some help and some guidance.

  • 13:56:36

    MACARENAYes. And where do you find that? I'm not finding anybody...

  • 13:56:40


  • 13:56:41

    SHIMIZUOh, so I have some good thoughts for you. And first of all, I would really recommend that you start small. Because then you can have some success. Start with close around your house. And then you can work out from there. That's really the best way to not become overwhelmed. And then to get some good designers. There's some good websites. I know that the landscape designers have a website. It's landscapedesigners.org. And they -- you can look up designers on their website based on your zip code. And I really recommend that. I think landscape designers are a good way to go.

  • 13:57:22

    NNAMDIThank you very much and good luck to you. We only have about a minute left, Holly. But the last time we spoke, you were still executive director of the U.S. Botanic Garden. You have stepped down from that post. What are you up to these days?

  • 13:57:32

    SHIMIZUWell, so now I'm leading a tour for the American Horticulture Society to New Zealand, which I'm totally excited about. And I'm doing lectures. I'm lecturing on uses for native plants for the Maryland Native Plant Society. And I'm writing an article about my own home garden and creating a new garden in Lewes, Del.

  • 13:57:53

    NNAMDIAnd good luck to you.

  • 13:57:55

    SHIMIZUThank you.

  • 13:57:56

    NNAMDII'm afraid that's all the time we have. Holly Shimizu is a conservation horticulturist, until recently, executive director of the U.S. Botanic Garden. Holly, always a pleasure.

  • 13:58:04

    SHIMIZUThank you.

  • 13:58:04

    NNAMDIDavid Ellis is director of communications and editor of The American Gardener at the American Horticultural Society. David, thank you so much for joining us. Looking forward to you joining us again in the future.

  • 13:58:15

    ELLISYou're welcome. And thanks for having me on the show.

  • 13:58:17

    NNAMDIAnd thank you all for listening. I'm Kojo Nnamdi. Coming up tomorrow on "The Politics Hour," are D.C. streetcars in peril after the council slashes funding? Virginia's stellar bond rating under threat, in light of a huge revenue shortfall. And Maryland's gubernatorial frontrunner sidesteps the dangers of a live debate by staying on the sidelines. "The Politics Hour," tomorrow at Noon on WAMU 88.5, and streaming at kojoshow.org. And for listeners in Ocean City, Md., it's "Coastal Connection," with Bryan Russo.

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