do a garden audit, with arnold arboretum’s rodney eason

do a garden audit, with arnold arboretum’s rodney easonNOBODY WANTS to get the IRS notice in the mail that they’re being audited, heaven forbid. But when it comes to gardens, Rodney Eason believes that the occasional audit is a very positive process, and encourages us to perform one on our own landscape.

Rodney became director of horticulture for the Arnold Arboretum of Harvard University (above) in the fall of 2023. Prior to that, he was CEO at Mount Desert Land and Garden Preserve in Maine, the director of horticulture and garden curator at Coastal Maine Botanical Gardens, and even before that, display leader at Longwood Gardens in Pennsylvania.

We talked about some insights gained from applying this audit thought process to the historic Arnold landscape, and also about the kinds of things we can look for in our home gardens, to keep them in scale and impactful. He even shared the app he uses to play with design tweaks virtually before he does any pruning or digging or other changes, and other great tricks.

Read along as you listen to the June 24, 2024 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on Apple Podcasts (iTunes) or Spotify (and browse my archive of podcasts here).

doing a garden audit, with rodney eason



Margaret Roach: Well, I have to ask you, Rodney: It’s your first full growing season at the Arnold, and I mean, how could you even get to know all the nooks and crannies and all the plants and, oh my goodness, what a situation to encounter and try to take in. Right?

Rodney Eason: It is, and as you said in the intro, we spent a decade in the Mid-Atlantic working at Longwood Gardens, and in the past decade up in Maine where the plant palette and the seasons are both very different, and it’s a very short growing season. So coming back to Boston, of course it’s not Philadelphia, but there are a lot of plants that can grow in this environment that grew around Longwood, in that area. And so it’s a bit of a homecoming. That said, there’s a ton to learn, for sure. It’s definitely a place with nooks and crannies, and I’m discovering new plants every day.

Margaret: Well, it must just be, I think I might be breathless all the time, you know what I mean? Just completely in awe, because it’s such an important collection with not just the aesthetic, the beauty of it, but also the historic and scientific importance of it.

Rodney: Totally. There are over 16,000 plants on roughly 250 acres, and I got a notice last night on Facebook, Dr. Tom Ranney from North Carolina State had posted a link to these new Chitalpa, which are Catalpa times Chilopsis hybrids that he had released from his research program at North Carolina State University. So I sent an email last night to our director Ned Friedman and Peter Del Tredici, who’s still working here as a research associate in his retirement, and Michael Dosmann, who’s our Keeper of the Living Collections. I sent them an email, “Excited about these Chitalpa hybrids” and Michael writes back, “We’ve already planted some of those.” [Laughter.]

Margaret: Oops. Ahead of the curve. Ahead of the curve.

Rodney: For sure.


Margaret: Well, I heard a rumor that you’re doing some pretty fun things there already in your new role as director of horticulture. Like a colleague of yours said, you’re bringing in enormous containers for plantings at one of the building entrances and including something like putting golden dawn redwood trees [above] in the planters [laughter]. I mean, drama things.

Rodney: That is true. One of the things that a lot of folks, when you come into the Arnold Arboretum, which was designed in 1872 by Charles Sprague Sargent and Frederick Law Olmsted, is that it’s different than most public gardens that people encounter where you go to the visitor center first.

Our visitor center is parallel to the entrance, and we’re a Boston public park, and some people may go right by the Honeywell building as the main entrance. And since we’re known for the U.S. arboretum that really brought or actually distributed the dawn redwood, we thought, “Wouldn’t it be fun to showcase the chartreuse version, the ‘Ogon,’ Metasequoia glyptostroboides ‘Ogon,’ and place them in large containers?” And then that way it catches the public’s eye and leads you up to the visitor center as a point of orientation.

Margaret: Well, that’s funny because I can see three of them that I have up at the top of my hill from straight out my office window right now. And that is one of the sort of garden audit things I wanted to ask you about, about sort of signals: finding one’s way around the garden visually, and the signals, and how sometimes as the garden ages they get lost.

So let’s transition to talking about garden audits. What’s the garden audit and why would I need one? And what does that mean to you?

Rodney: It’s a great question, and I feel like sometimes because gardens, depending on the designer and the people who are taking care of it, they may be locked in this sense of permanency. And we know that saying that horticulture and gardening are the slowest of the performing arts, and so the play is never done. Plants continue to grow. Seasons change; as we’re noticing our climate is changing. And also there may be plants, for example, here at the Arnold Arboretum that were planted back in the late 1800s, early 1900s, which are now invasive exotics.

So it’s important to go through the landscape and for example, Phellodendron amurense, which these majestic cork trees, they’re now seeding around. So if we have one in the landscape that we may want to remove it to open up a new vista to either A, the Boston skyline or to our south, the Blue Hills, we may take out that mature tree because from an environmental and conservation standpoint, it’s probably not a great message to keep that around. Although when it was brought into the landscape, it was thought of as important because it was a new tree. Now we can change our minds. It is O.K. to change your mind.

Margaret: So some of the audits are edits [laughter], some of them are removals, and some of them have to do with sort of the ethics and the new knowledge about the environment and ecology.

Rodney: That’s right. And then some of the audits are looking at what people have done, and it may have been in vogue at the time. And one audit that we’re doing right now is at the top of Bussey Hill [above]. So Margaret, are you familiar with the Arnold Arboretum?

Margaret: Yeah, a little bit. But tell people what Bussey Hill is, because that’s an important feature.

Rodney: In the sort of core area of the Arnold, there’s a winding pathway, actually a carriage road that leads to a top, which was a vista. So when Olmsted designed it, in plan view, it’s almost like he laid it out as an Archimedes spiral. I don’t know if it’s truly a golden proportion, but there’s some golden-esque elements to it. And then when you get to the top, it’s anticlimactic. There’s a ton of asphalt. The views to the Boston skyline and to the Blue Hills are obscured. So it just didn’t make sense. So in the past month or so, I’ve looked back by working with our librarian and historian Lisa Pearson here on staff, and she’s been able to share with me Olmsted’s original designs.

And a couple of things emerged through that process. Olmsted went through numerous iterations. His initial designs for the top of Bussey Hill were never built because either due to the topography or when they started laying out the roadways, it was built differently than he anticipated. And then once it was constructed, he had envisioned a carriage turnaround. So when the Arnold Arboretum was initially laid out in 1872, it was thought that a lot of people would visit on horse and carriage. And since those days are long gone, the only people who ride horses through the Arnold Arboretum are the Boston Park Police. So we need to reexamine how that might work.

And as you know, Margaret, if you’ve seen my Instagram, I love riding bikes a lot around the city, and I see that as an opportunity to study other landscapes. And adjacent to the Arnold Arboretum is another Olmsted design, Franklin Park, which is our neighbor to the east, and also part of Boston’s majestic Emerald Necklace. There’s a summit there with a similar spiraling carriage road. And when I got to the top, I was riding my bike up to the top and there was that elliptical turnaround as Olmsted had originally designed for Bussey Hill.

And what has happened at Bussey Hill is that in the seventies, someone decided it would be great to install a parking lot at the top [laughter]. I know. It was such a horrible intervention. So we’re going to go back and we’re going to remove the asphalt. We’re going to restore the ellipse and create new seeding areas and vistas that will allow these dramatic views as was originally intended. [Below: An aerial view of the Arnold, 1936.]

Margaret: Well, I don’t have a parking lot as an impediment in any of my views or whatever, but as I was mentioning before, I have for instance, these three gold Metasequoia up the hill and various other things on axial views from the house, from my key windows that years ago I placed gold things at the terminal end of a view, and in some cases along the way and so forth to draw your eye out into the farther reaches. Well, but guess what happened? The things in between here and there all grew [laughter]. In the meantime, the damn plants got bigger, huh? The trees and chefs.

Rodney: I know. I don’t know if you’ve ever read “Second Nature” by Michael Pollan.

Margaret: Yeah.

Rodney: I love the book because it’s kind of a Thoreau-esque examination of becoming a gardener. And that is the problem is that we plant things and the plants, darn it, don’t read the books about how tall they should be. And so you have to go through periodically and either prune or remove and make a determination like what’s most important to you, that golden Metasequoia or the… I don’t know what’s in your garden, but let’s just say it’s a Cotinus that has grown up and obscured that view. Can you hack back that Cotinus to allow some oblique views to the ‘Ogon’ Metasequoia in the distance, or is it time to replace the Cotinus with something that’s lower growing, maybe a lower-growing Cotinus or a different shrub altogether?

Margaret: Right. And that’s really, so that’s part of the audit is to, again, not as significantly and historically as your example with the Bussey Hill and the original plans for it and so forth. But going back to those, but to sort of try to remember what you were intending and then looking at it and saying, “Well, am I still happy with this?” And if not, what could be the possible remedies, before we take any action? I suppose we want to say give ourselves some time to think through, “Well, I could do this or I could do that.” Like you’re saying, “Is there a shrub I could cut back or is there something else I could remove?” Or really ponder the possible ways, or can I be content with that? Yeah.

Rodney: And time is essential because you can’t glue branches back on.

Margaret: No, no.

Rodney: Every cut is essential. And I’ve found that the iPhone is a wonderful tool for just going around and taking photographs and then holding onto those photographs and looking at it. And what I’ll sometimes do Margaret, is take those photographs and use the iPad. I use a program called Procreate and go in and you can kind of do Photoshop on the fly, but use an Apple Pencil and draw in shapes and give you an idea of what that vista might look like before you go in and cut something out or add something else.

The other thing that I really enjoy doing is inviting people that I trust, people who either have a great eye or know plants, and have a walkthrough together. Because what you might think needs to happen, you might get a great idea from a friend or a professional colleague, and it’d be like, “Oh, that was the idea I was looking for.”

Margaret: The other thing I find, and a lot of gardening friends say this to me and we lament about it together, who have older gardens. I’ve been here 35 or so years, and is that the pathways… The beds get bigger [laughter] and the pathways get smaller. The space between them gets smaller. So a lot of places where you could see from one garden area to the next, you might see there might be a narrowing, a pathway, that would sort of lead your eye again, from room A to room B, so to speak, or area A to B. It’s getting overgrown, and that’s an unfortunate, congested feeling. It doesn’t give that “Aha, look, I’m going to go over there next.” It doesn’t invite you. And sometimes the paths are just turf, and they’re getting so narrow that they’re a mess and rethinking those heavy foot traffic areas that have gotten worn away or no longer serve well enough.

Rodney: Totally. And when you do you want to, whether it’s, let’s just say hypothetically like the dwarf Chamaecyparis that you planted 30 years ago: Dwarf conifer is a relative term.

Margaret: I was going to say dwarf. Uh-huh. Yeah, right. That word is a silly word [laughter].

Rodney: Yeah. Chamaecyparis in nature might be 85 feet tall, but a dwarf Chamaecyparis is only 25 feet tall, but that’s still too large.

Margaret: It’s not 3 feet tall.

Rodney: Right, exactly. So do you want to keep that and knowing that the turf is now worn down, you make a determination, “Do I want to keep my pathways turf or can I transition those over to mulch, or do I want to use decomposed granite?” So you can have options there to decide A, do I want to keep the plant, or do I want to switch the plant out? That’s sort of the first determination. Or can you prune it? Conifers don’t lend themselves well to pruning unless you take many years to do that. So you could switch the pathway out.

And then the other thing you mentioned is if you want to draw someone down a pathway, you could introduce an element like a tuteur with a vine growing on it as a bower to sort of draw the eye along the pathway. Or a beautiful container with something as we said earlier, like a golden Metasequoia or Cotinus ‘Ancot,’ that golden-leaved Cotinus or one of the golden-leaved redbuds. Something just to draw you down that pathway.

Margaret: To announce it even more loudly than it currently is with its sort of aged status [laughter] with some of the overgrowth and so forth that’s happened. Yeah.

Rodney: Exactly. And I’ve spent my entire career in public gardens, and one thing that often happens is signage and interpretation goes in. And I feel like if we could do that instinctively and horticulturally, I prefer to use as little signage as possible. And I think for the home landscape, very few people have signs in their garden unless they’re for fun. And so how can you do that with horticulture and horticultural elements? And you can go along and look at other areas as precedent.

I mentioned my wife, Carrie, and I went to Great Dixter back in April, and we were having lunch with Fergus Garrett and his staff, and I was like, “Fergus, how do you stay inspired? You’ve been here for 30 years, what inspires you?” And he said, “Everything. Everything inspires me. Whether it’s going to a local museum, it’s seeing a textile, it’s going to a movie, it’s music.”

So I think as you go along and you begin to audit your landscape, think about things that you can draw from. What are the inspirations that you can be creative and artistic and pull that element into the landscape?

Case in point, there’s a garden at Great Dixter that’s overgrown [above, one path at Dixter recently]. And I mentioned that to Fergus. I was like, “It felt like things were growing into the pathway.” And he’s like, “Yup, we want people to be uncomfortable and touch the plants and have them brush up against you.”

Margaret: Interesting. A little bit wild, huh?

Rodney: Exactly.

Margaret: Wild. Yeah. I think one of the first things I did when I came here was dig a couple of water gardens that have been permanent in-ground features. They’re aligned with a thick… I don’t know what it is, like an EPDM or I don’t know what it is, some kind of textile, rubbery textile. And they have plumbing and stuff in the warm season. And the water is always the biggest hit with all of the wildlife from the smallest to the insects and so forth up to mammals. And everybody comes for the water.

And lately I’ve been thinking, “Well, why aren’t I repeating that in other areas?” Not big in-ground features necessarily, but just even, I saw a picture recently someone’s place, she had almost a shelf. It looked like a shelf, but it was a top of a wall next to her patio, and she had placed glazed saucers, big saucers, kind of almost like you’d put under a big pot, on top of it, maybe a half a dozen of them. And she keeps them filled with fresh water. And I mean the number of birds who stopped in there and sometimes it looks like a menagerie [laughter]. I just thought, “Wow, what a beautiful, simple thing.”

And so I already have a water theme going on, but why aren’t I moving it around the garden and putting it with such an easy thing like that in a few other spaces and maybe that can freshen it up. So one of my audits was repeat the water idea in easier new ways.

Rodney: That’s essential, Margaret. It’s your garden and you know what you like and your taste should be your taste and not necessarily what other people want to impose upon your space. And so digging out a pond and applying an EPDM liner, you and I both know that is a hell of a lot of work.

Margaret: I was young once, Rodney. [Laughter.]

Rodney: Yeah, exactly. So can you go to the local ag-supply store and get a stock tank and plant things around the base of it or paint that galvanized metal a matte black so that it fits within your landscape, and then steal that idea from Chanticleer where they have the container that’s sealed and they float fresh flowers on it. It may not be so essential to wildlife, but it is sort of a pop for your visitors.

Margaret: So in auditing, we may be looking for things that have all kinds of different impacts, both decorative and in some cases ecological, and maybe repeating other themes we have in a bigger or smaller way already in the garden.

What are some of the other kinds of things like in audits that you’ve ever suggested to people or you think about?

Rodney: What I’ll look at, well, one of the essential parts of an audit is I think folks should begin by looking at the climate, the microclimates of their site. Again, whatever might be on the USDA hardiness zone map doesn’t get down to the specific level of your property. So you might be a zone 5 or zone 6, but that northwest side by your chimney, if you’ve got a brick chimney, that might eke out a zone 7. You might be able to get away with an Edgeworthia. We all have zone denial [laughter], so find out those pockets of zone denial. And likewise, where are the cooler spots where you might be able to get away with some foxgloves that will last a little bit longer into the season and have things continue on?

The other thing I would encourage everyone to do is A, test your soil, and B, learn how to read a soil test. Because knowing what the composition of your macro- and micronutrients are is great. And if you don’t have the time or the resources to amend your soil, then make sure you’re planting the plants that can thrive in those type of conditions. If you have a very acidic soil, of course you want to stick with ericaceous plants—the azaleas, rhododendrons, blueberries, also some of the viburnums. So really learn from what your existing conditions are and adjust to that.

If you want to grow specific plants, you may have to alter some of the soil or alter some of the conditions to be able to grow. And then there are times when people want to plant things that won’t necessarily grow there. No matter where I’ve lived on the East Coast, people have tried palms. They grow great in the coastal Virginia and south of there. Everywhere else, you’ve got to sort of rig it up to grow Trachycarpus or a needle palm. If you’ve got that time and you’re willing to do it, great, but otherwise leave it to the folks down South.

Margaret: I was just going to say, you mentioned climates and microclimates, and in terms of auditing, I sometimes think we all had better audit our sort of brains about what to do when and when the garden does what, and that sense of inner calendar that we have, where we thought we knew the place and what was going to happen when. Because boy, it’s changing so fast.

And of course that’s part of the mission there at the Arnold is that you’re observing that and figuring out what’s going to happen, how to help in what happens next with climate change and so forth and its impacts. But yeah, I’m a little mystified at the moment. I think I could use to audit my schedule [laughter] for how I manage.

Rodney: I don’t know about for you there in the Hudson Valley, but it felt like here in Boston, we didn’t really have a winter. Of course, I’m moving down from Maine.

Margaret: Right, right. No, but I agree. It was not 3 or 4 feet of frost in the ground all for months. No, no, no. Definitely not.

Rodney: So we’re seeing things flower and survive here that may not have flowered or are flowering early. And I’ll give you an example. In one of our warmer areas, the Explorers Garden, which is adjacent to the Bussey Hill summit that I mentioned earlier, Michael Dosmann, and others collected a northern ecotype of Southern live oak. And believe it or not, we have Southern live oaks that have been growing for almost a decade here in Boston. They’re not going to look like the majestic trees of Charleston with Spanish moss draping over them, but… It could be two decades from now, Margaret, Boston could have live oaks growing on the Common, who knows? But at least we’re testing that and beginning to see, as Boston has to adjust its street tree planting, what’s the next palette?

Margaret: Well, right. So that’s going to be the biggest audit of all [laughter]. Well, Rodney, I’m so fascinated to talk to you. I hope that you’ll come back and we can talk about some of your other acts of daring in horticulture there and so forth in the future. And again, congratulations, and it just sounds like the most wonderful assignment ever. So thank you for making time today to talk about it.

Rodney: Thank you. It’s a dream come true. And please come and visit. I’d love to give you a tour around.

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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 15th year in March 2024. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the June 24, 2024 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes/Apple Podcasts or Spotify (and browse my archive of podcasts here).