LOOKING AROUND the garden as some of spring’s showoff shrubs and perennials fade, I realized how glad I am that I made room for some gardens-sized trees, too—not too big and not too small, and the best of them offering more than a single season of interest. Choice trees for the garden, and also some unexpected ways to use them, was the topic of my recent discussion with Bruce Crawford.
From 2005 to 2020, Bruce was the director of Rutgers Gardens, the botanical garden for Rutgers University. He’s currently the State Program Leader for Home and Public Horticulture with the New Jersey Agricultural Experiment Station, and a longtime instructor in the landscape architecture program at Rutgers.
We covered natives from shad and sourwood to pawpaw and even Franklinia, plus imports, all with a wide range of qualities to recommend them (that’s the Rutgers-bred kousa dogwood ‘Scarlet Fire,’ above).
Read along as you listen to the June 7, 2021 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 or Stitcher (and browse my archive of podcasts here).
choosing, and using, garden-sized trees, with bruce crawford
Margaret Roach: Hi Bruce. I’m so glad we’re going to talk about this today, I’ve been going out and looking at all the trees in my yard [laughter].
Bruce Crawford: Margaret. Yes, trees are one of those, I think, often-underappreciated plants in the landscape.
Margaret: Yes. And, again, like I said, in the introduction, suddenly there’s a lot of like frowzy-looking stuff that’s going by at the perennial layer, and the lilac blooms are gone and whatever. And I’m looking to the trees and I’m thinking, “Ooh, this is going to be nice.” And some of them came earlier, and already came and went, the blooms and so forth. But anyway, maybe we just start with when I say garden-sized trees or we say small trees, we don’t mean bonsai [laughter].
Bruce: True. True.
Margaret: What do we mean?
Bruce: Yeah, no, I once worked for a gentleman who always was talking about a small tree, and he’d say, “Dogwood.” Everything was dogwood. So finally I asked him, “Do you really want dogwoods all over the place.”
And then his wife chimed in and she said, “No, no, that’s the only tree that he really knows. So he’s just looking for a tree that gets up to around 20 feet tall to maybe 30 feet, and flowers.” And so that’s what he was looking for. It’s interesting how there’s so many trees, but, again, many of them don’t get out for the public to see or to know that they exist.
Margaret: So, maybe we’ll start with some that are happening now, or now-ish, because as I said, a bunch have already flowered and we can double back to those. But in my yard, and I’m north of you in the Hudson Valley of New York State, the native fringetree, Chionanthus virginicus [above], and the kousa dogwoods are going on right now. So maybe we can start with some of those, are those on your list of small trees that you recommend?
Bruce: Yes, they are. And the fringetree is a great understory plant. Understory, meaning that it will grow underneath an oak tree or a tall story of trees, of shade trees. And it’s dioecious, which means there are male and female plants. And the males tend to have slightly showier flowers, plus the anthers add to the body of the white flower. But they look, literally, oh, how can you explain it? They’re draping down, and they sort of look like a white beard, each one.
Bruce: But the female plants are great, too, because in the fall they come on with these dark purple fruits and the birds absolutely love them. So if you’re interested in wildlife, as I am, and trying to learn more about the birds, just planting seedling fringetrees in the garden, the Chionanthus is just a great way to attract wildlife.
Margaret: A friend of mine, who’s a nurseryman, when I was interested in one, years ago, he said, “Well, Margaret, come look at them in the fall, in the fields,” where he grew them. He said, “Come look at them in the fall and pick the female that has the nicest fruit,” because they weren’t all the same.
Margaret: Apparently, they can vary, and some can be bigger and more profuse and so forth [above]. Those beautiful bluish-purple, like you said, those dark fruits, really gorgeous. But yeah, and it’s sweet-smelling, the fringetree flowers, aren’t they?
Bruce: Yes. Yes. Very nicely scented. And it has a nice rounded shape to it, which again, just looks really attractive in the garden.
Bruce: It doesn’t take up a lot of room. If you have a harsher… There’s also a Chinese fringetree, which has a slightly thicker leaf to it, and at Rutgers Gardens, it was planted next to one of the on-ramps to Route 1, and got tons of road salt on it in the wintertime. And it never flinched. It just kept right on going. It looked great.
And we don’t really know how old that one was or is, because it was never accessioned, but I’m guessing it’s probably 40, 45 years old, and it’s doing great. So, again, if you’re near a road and you want to put up a tree that gets up to about 25 feet tall with, again, spectacular white flowers, Chinese fringetree is a great plant as well.
Margaret: So that’s Chionanthus retusus, is that right?
Bruce: Yes it is Margaret.
Margaret: And the native, not literally native to the Northeast, but I think a little further south, although I think it’s migrating up the coast…
Bruce: Yeah, yeah.
Margaret: … the native one is virginicus. Yeah.
Bruce: Yep. Yep. So, if you’re looking for a spectacular one to see there’s a beautiful one down at the Morris Arboretum outside of Philadelphia. And they have some spectacular big ones of our native one or virginicus, so, anyway, worth a trip to go.
Margaret: So Rutgers, where you’ve spent much of your career so far, they’ve done a lot of work with kousas, haven’t they, the Korean dogwoods?
Bruce: Yeah. Elwin Orton, Dr. Orton, started crossing our native flowering dogwood Cornus florida with the Chinese dogwood way back, in the late ’60s. And he was trying to get a pink-bracted or a pink-flowered or a red flower, even better, Chinese or kousa dogwood. And he tried and tried and tried, and they came up with a number of really good selections, called the Stellar series, but he never got that red kousa dogwood.
And so Tom Molnar, Dr. Molnar, who took over for Dr. Orton, he literally just put all of Dr. Orton’s plants together and let mother nature do it. He just let them be open-pollinated, and then he collected the seeds from them, lined them out, and after he did this twice, which is about 4,000 seedlings, he found ‘Scarlet Fire’ [photo, top of page].
And ‘Scarlet Fire’ has just got deep, deep red flowers to it, and it grows beautifully. It’s got a nice straight stem. And again, that’s one of the things that they look for is, not only does it have attractive flowers—and a kousa dogwood also has attractive fruit in the fall, nice, large red fruit—but it’s got to grow well or otherwise the nursery folks are going to look at it and go, “No, we’re not growing that. That just is not appealing to a homeowner when it’s small.” So ‘Scarlet Fire’ is a winner. It’s just a great, great kousa dogwood.
Margaret: Oh, good. O.K. That’s one I didn’t know about, and the kousas, I think, don’t they have nice bark as well, and fall color?
Bruce: Yes. Yes. They come off in patches, because as the tree expands, some trees get more of a ridge and furrowed, as the barks splits and grows with the diameter of the trunk. And some of them just the outer bark just sort of pops off to reveal an inner bark. And there’s one, which was the pollen source that Elwin used, Dr. Orton, at Rutgers Gardens, I’ve nicknamed it Patches [laughter], it’s just a great tree. It doesn’t have a name, it’s just a seedling-grown plant, but it’s got the most gorgeous bark to it. It looks like, literally, a patchwork, and so I’ve sort of given it that nickname.
Margaret: Now, if I go across my yard to the outer perimeter, I think, before long, in one direction, I think the sourwood or Oxydendrum should be blooming. And I think then a little later than that will come some Stewartia blooms. So maybe those are two… I think, those are on your list, too.
Bruce: Oh, yes. Yes. Stewartia is one those interesting plants that… When I was starting out, I had my own business for a number of years, and I kept putting it in a drier location. And it wasn’t until later I realized that stewartias actually benefit from a moister location or a lot of organic matter in the soil to hold in the moisture.
But there’s a number of species of Stewartia, almost all of which have really nice white flowers in the summertime, and then really interesting sort of camouflage-like bark in the winter—again, patches. And the Japanese stewartia sort of has some pinkish underbark to it as well, which really adds to its yearlong interest. So yes, stewartias are fantastic. Monadelpha is another one, they’re called the tall Stewartia, which has orange bark and very, very striking in the landscape, especially, with some evergreens behind it for a winter interest. So I’ve become very, very fond of that one.
Margaret: I guess I have the pseudocamellia, Stewartia pseudocamellia is the one that I have [above]. Yeah.
Bruce: Yeah, the Japanese one, so-
Margaret: Yeah. And I’m always glad for those fresh white flowers when it’s heating up, sort of the beginning of summer, and it just looks clean and crisp and refreshing.
Bruce: And you know what’s fun about it, too—and some people argue this point. I remember I knew one gentleman who didn’t like Magnolias because he didn’t like the petal drop on the ground. But when the flowers fall from the stewartias and they sort of layer the lawn or the bed underneath it, they look really pretty still. So it has both, they look great on the tree, and then they look right on top of the ground as well. So it’s a sort of a different way to appreciate the tree [laughter].
Margaret: Well, that’s a very Buddhist, very Eastern perception, because the sort of “nothing lasts,” “carpe diem” kind of philosophy, and that we should celebrate not just the peak moments, but the passings of things as well and honor them.
Margaret: So that’s very, very, very Eastern of you, Bruce [laughter].
Bruce: Thank you. And you mentioned sorrel tree before, and the one advantage that the sorrel tree has over the Stewartia is really nice fragrance to it. And the flowers actually look like little lilies of the valley on the flower racemes of the tree.
And so, again, there was an old one that was young when I was at Rutgers. In 1980, it was a newly planted tree and it was only about 3 feet, 4 feet tall, and now it’s upwards of about 20, but it’s loaded in early July with these beautiful white flowers. And again, it’s one of those trees, which I’m always surprised that more people don’t try or fit into their landscape. And it really is very, very showy, something blooming and early to mid-July, and then it comes out with this phenomenal fall color, which just blows your socks off. Why people aren’t sort of gravitating to that a little bit more, always surprises me.
Margaret: That’s Oxydendrum arboreum, I think, the sourwood or a sorrel tree is that right [above]?
Bruce: Yes it is.
Margaret: Yeah. And that’s an American species, isn’t it?
Bruce: Yeah. It’s a little more southern typically. You see it growing large in the mountains of North Carolina and so forth, but it’s perfectly hearty up here. There’s probably just one drawback, which is why a lot of nursery folk aren’t really super-fond of it, is it takes a while to figure out if it’s going to be a tree or shrub, before it really starts to produce a true straight stem. So unless from day one, someone stakes it up and really trains it to begin with—but if you have to grow it as a seedling and don’t stake it, it’s one of those plants that scratches its head for quite a while, trying to figure out, “Do I want to be a shrub or should I be a tree? I don’t know.” Until finally figures it out, it needs to be a tree.
Margaret: Well, speaking of that, the genus Amelanchier, the shadbushes or shadblows or whatever, serviceberries, whatever we want to call them, they’ve already happened [shad flowers, above]. They happened super-early, in terms of their flowering, but there’s confusion in those. I think there is one, that’s more tree-like, but a lot of them are more shrubby is that true?
Bruce: Yeah. Amelanchier canadensis, is more of a shrub and that was the biggest mistake—I thought it was a big mistake, but the homeowner never worried about it—but when I did a garden over a several years, and so I went out and I bought what I thought was the tree form, and it turned out to be a shrub form. So I had two trees and a shrub, and I was trying to do a matched pairing, and obviously, it didn’t work out. So you have to be very careful with your nursery sources, but there’s several really good… Lamarckii is one, which is a tree form, which is native to Northwest New Jersey, which gets upwards of 35 or so feet in height.
And then there’s grandiflora, which is a naturally occurring cross, and again, you see that throughout the woods of Northwest New Jersey. And it comes into bloom before the trees have leafed out, and so they’re really easy to spy on the side of hillsides and mountains and really, really a pretty plant. The flowers only, unfortunately, lasts for about a week.
But then they’re followed with these blueberry-like fruits, which again are great for birds. And I had a friend of mine who would make a blueberry or Amelanchier, I should say, pie. And a little bit tarter than a blueberry, but still really good. So if you can get out there and compete with the birds, you can make some pies out of it, which are good.
Margaret: Well, the cedar waxwings in my area, know, they have me on their GPS apparently [laughter]. And honestly, before they’re even ripe, they are here and they are just waiting. They take every fruit from every shad that I have, so it’s really funny. It’s like a clockwork every year. And it has good fall color, too. I think doesn’t it?
Bruce: Yeah. No, they do. A lot of good reds, typically, with a little bit of orange, so yeah, a spectacular tree. And very native [laughter].
Margaret: Yes, exactly. Exactly. So any others noted for their flowering that we want to highlight?
Bruce: Well, since we touched on edible, we could look at redbuds, because, again, another native small tree; not terribly long-lived 15 to 25 years or so, could be a touch longer. But again, they produce these not red, but more pink or lavender flowers in late April, but they’re edible.
Bruce: And so, they look great on salad. They taste just like peas. The plant’s in the pea family and the flowers tastes just like peas and they look great on salads. And so people are always trying to think of something a little bit interesting to add to the table. And also I’ve never done it, but they said that you can, when the seedpods are small, you can stir fry them and cook them, but I’ve never done that.
Margaret: You’re taking edible flowers to a new dimension.
Bruce: Yeah. Yeah. So it makes it fun. And then another interesting small tree, which used to be sort of a Southeastern native, that’s perfectly hardy here but now it’s extinct, is the Benjamin Franklin tree, Franklinia. Named after, of course, Benjamin Franklin. And it was found in the wild in the late 1700s, and I think, if memory serves me correct, it was last seen in the wild in the early 1800s, but never seen since.
And it’s a much later-blooming plants, so if you’re looking for a camellia-like white flower, quite large, 3 inches or so in diameter, with a boss of yellow anther right in the middle, really showy [above]. And though, it’s a very small tree, 15 to 20 feet tall, and looks great fitted into a light shaded location. It just needs good drainage. That’s the key thing for it.
Margaret: Oh, huh? I’ve never grown that. That’s one… It was kind of the holy grail when I was making the garden and buying trees in the beginning, to begin the design here and so forth, it was such a precious thing and so hard to find.
Bruce: It’s now getting a little bit more fanfare. I’ve seen several nurseries now starting to line it out and grow it as a balled-and-burlapped tree. And it’s doing remarkably well in the field. So I think that would be one that you might see more frequently than you used to.
Margaret: So I want to make sure we have time for talking about how to use some of them. But one tree I want to ask you about before we get onto that is, not fruit for the birds, but fruit for people. The pawpaw [Asimina triloba], another native tree, yes?
Bruce: So yeah, pawpaw is an interesting… you see it a lot from Maryland south, it’s an understory tree. So again, it likes to grow in the shade, typically, but it will grow very well in full sun. We planted them at the gardens, several colonies of them. And they come on with this mango-shaped and appearing fruit. And it ripens in early to late September, and it has a mango-like taste to it, a mango-like scent to it, but it has a custard-like consistency. So it’s sort of, once you cut it open, it’s easier to eat it with a spoon than it is to eat it otherwise.
And when I would take the students over, we’d be in the gardens looking at perennials for a herbaceous plant class, but I would always drag them over to the pawpaw trees, and say, “Hey, have you ever had a pawpaw?”
And they’re looking at me like, “What’s a pawpaw?”
And they’re quite deer-resistant. There’s quite a few deer in the gardens, but we never really had it grazed by the deer. So it’s an interesting… and there’s also a number of selections out, which have supposedly better-tasting fruit, even though every one that I’ve tasted is really quite good. And you can make ice cream out of it, too, and other cocktails and so on. So there’s quite a few different things you can do with pawpaw trees.
Margaret: Huh. So you’ve kind of hinted at… A couple of times you mentioned more than one tree in a grouping and so forth. So do you have some advice for us, if we’re going to add more trees of these smaller trees, other ways to use them besides that typical, here’s one along the front walk, as you get to the front corner of the house kind of thing—plop, here it is, this one sentinel kind of thing.
Bruce: So yeah. So again, I think people usually just see a tree used in most yards, they think, well, let’s just repeat what we see. But, again, some of the trees, even though they’re considered to be small trees, they get to a nice stature and they look good worked into three or so off the corner of the house.
And a lot of times you want to have a walkway that goes around the corner of the house. And so by placing aone on one side of that walkway and two on the other, it softens the corner of the house a little bit better. And then it allows the walk to be even more interesting, because now instead of walking around a tree, you’re walking through a grove of trees, and it really makes the transition of spaces from the front yard to the side or the backyard far more interesting.
And the one I’m thinking that we used was a called a Persian ironwood, Parrotia, because it has flaking bark in the wintertime [detail below]. So again, as you walk along, regardless of what time of the year you walk, you had something interesting to look at because it has beautiful foliage as well.
Margaret: That has amazing fall color, the Parrotia.
Bruce: And another fun thing, which I like to do is plant them as small allees, and it doesn’t have to be anything grand or pretentious, but off, say, the sliding doors going out to the back patio or something like that. If you put in four or six—so it would be three on either side—trees, small trees as a little allee, leading your eye back to the back end of the property, it’s fun.
Whether they’re flowering trees or you’re just really growing them for their foliage, and for that effect, again, people don’t think about using them in that way. And it gives the… and especially if you use forced or false perspective, where the last tree is set a little bit closer together, then the first two trees, that makes the allee seem like it’s much longer than it really is. And again, makes your property look all the more large, which again, when you’re looking, if you’ve got a half-acre or an acre piece of property, it’s a great use for small trees.
Margaret: I wanted to ask you about one, it was in an article I read of yours, Maackia, that I’ve never grown. I don’t even know if I’ve ever seen it. Maackia—is that correct?
Bruce: Yeah. Yeah. Maackia amurensis [above], it’s from the northern parts of China, very, very cold. It’s in the pea family, so it’s a legume, so it fixes its own nitrogen, so it grows in the worst soils. We’ve grown it up in Sussex County in a commercial situation where it had a little pocket of topsoil that it was planted in, but then it grew out into gravel and subsoil all around it, and they’re thriving.
And so it blooms in the middle of summer. It has white flowers, typically, mid-July to early July bees love it. So even though it’s not native to the Northeast, it’s again, still appreciated by the pollinators. And then the bark is cinnamon-colored and it has these little rivulets that run down the bark.
And then in the springtime, when the foliage unfurls, it’s silver and it turns green, but again, since it grows in a really cold climate, it has the foliage is initially pubescent or hairy. And it has those hairs on the foliage to, again, accommodate late frost, so it won’t be knocked back, but it’s beautiful. So it provides interest in several months of the year. So it’s a great, great plant, just again, underappreciated and not really seen very often.
Margaret: Well, Bruce Crawford, I want to know more and what I want to tell everybody is that there are links below for more information and so forth, and also some links to some of your great articles.
I’ve really been enjoying the monthly garden calendar that you do, the article that you do and post online, and lots of other stuff. So thank you so much, and I hope we’ll talk plants again soon.
Bruce: Oh, thank you, Margaret. This has been great. I really appreciate you having me on the show, and it’s just been fun to talk plants.
more from bruce crawford
- Bruce’s articles, including a helpful monthly garden to-do calendar
- His profile of Chionanthus, the fringetrees
- His pawpaw profile
(Photos of ‘Scarlet Fire’ dogwood, Chionanthus flowers, Oxydendrum, Maackia, Amelanchier, Parrotia and Franklinia by Bruce Crawford.)
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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 11th year in March 2020. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the June 7, 2021 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes/Apple Podcasts or Spotify or Stitcher (and browse my archive of podcasts here).