IF SOMEONE SAYS HYDRANGEA, many of us first conjure classic images of big blue moptops, or maybe the paniculata types with their conical white-to-pink-to-tan flowers. So you think you know a hydrangea when you see it? Well, chances are if Daniel Hinkley were asked to describe the genus, his version would be a whole lot more diverse than ours.

Dan Hinkley is a longtime plant explorer (that’s him in the Himalayas, below), nurseryman, teacher and gardener. Above all, he says, he’s committed to “above-average garden plants.” I found out from Dan just what, when the subject is hydrangeas, qualifies as above average and even exceptional, and we took a peek into the future of what traits hydrangeas of tomorrow might show off, too. Sneak peek: red flowers, or foliage that’s evergreen or felted or even purple are just some of the standout features we might see more of in hydrangeas of the future.

Plus: at the bottom of the page, learn about how to visit Dan’s garden undertakings at Heronswood—the former specialty nursery he founded that is now a public garden—and at Windcliff, his home garden, both across Puget Sound from Seattle.

Read along as you listen to our conversation on the August 28, 2017 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

hydrangea q&a with dan hinkley

Q. I guess a little background first: you’re north of Seattle, in the Kingston area?

A. We’re north and west of Seattle, so we’re in the west Sound country, looking back across Puget Sound to Seattle.

Q. Not a bad view.

I think of you all the time because not a month goes by here in my garden in the growing season when I don’t uncover, in the beds or in the compost heap sometimes, one of those turquoise-colored plastic labels from the old Heronswood mail-order nursery that you founded in I think 1987. [Laughter.]

A. Yes, it started in 1987, and those turquoise labels with large prices attached to very small plants.

Q.  Well those plants were good investments, as it turns out, because many of them—as small as they were then—are very big now. [Laughter.] Something went right. So tell us: Heronswood was a nursery, but now it’s something else. [Above photo, a border at Heronswood today.]

A. I’m having a wonderful time. It was a nursery from 1987 to 2006, and then it had an off period of six years, where nothing was happening here and the gates were closed. But since 2012 it’s been owned by the Port Gamble S’Klallam Indian Tribe, and I’ve been brought back in as the director, and in charge of its renovation efforts.

We have reassembled a staff, and we have a great volunteer base, and we are re-revealing the garden and making it better—not trying to recreate what it was but trying to add a polish and the go forward and put it on good footing for future generations of gardeners to enjoy.

Q. So it’s open on Fridays or other days as well?

A. We’re open five days a year as a Garden Open, where we have plant sales, but then also every Friday in the growing season and the fourth Saturday of each month. That’s going to increase because our attendance is increasing. Next year we’ll be open every Friday and Saturday during the growing season, and hopefully we’ll be able to add days on going forward.

 Q. So as promised, we’re going to talk about: I say HyDRAINgea, and you say…

A. HyDRAINgea. [Laughter.]

Q. I thought you said HyDRANNgea.

A. They all refer to the same plant.

Q. I’m teasing. [Laughter.]

A. It’s just a great genus of plants, and chock full of wonderful species—a greater diversity than most people realize.

Q. I know that we have some native American species, like arborescens—which people might know from ‘Anabelle,’ a big white round ball of flowers; a lot of old-fashioned homes have them. And we have quercifolia, the oakleaf, in the Southeastern United States, right?

A. Right.

Q. And I know there are some Asian species, but you’ve sort of seen the globe. Tell us about the range of where you have seen hydrangeas.

A. It’s pretty amazing. As you say just two species in North America—a paucity of species. But as you go south into Mexico, the number of species begins to skyrocket, right into Central America and the northern part of South America. That’s really a hotbed of speciation of Hydrangea. In fact, just last year an additional 15 species of Hydrangea were identified in the mountains of Bolivia and Colombia and Venezuela and Peru, so really our knowledge of the genus in that part of the globe is pretty small.

Q. Wow. [Above, H. serratifolia, an evergreen climber from Chile.]

A. And it’s also fairly exciting, because these are all represented by climbing species, and always evergreen. Not shrubs or trees, but they’re evergreen climbing species and their colors range from pure white to very, very rich red.

And that continues all the way down south to Tierra del Fuego; you can have evergreen climbing hydrangeas all the way to the southern part of Argentina and Chile. So even though in our minds we have, as you mentioned, mopheads and lacecaps and shrubs that we have grown in our gardens for generations in this country, really the lion’s share of the genus is unrecognizable to most gardeners.

Q. What about Asia, parts of Asia? Is there a diversity, and what are they like?

A. Pretty extraordinary. I have a good number of species in my garden from Taiwan, Vietnam, the northern part of India—Sikkim and the Arunachal Pradesh. Bhutan is certainly a hotbed of speciation in western China, and it radiates out all directions from there.

Generally, when you see a Hydrangea in the wild in blossom, even a lay gardener will recognize it as a Hydrangea, but the foliage is quite diverse. Of course the flowers can be across the board as well, but generally speaking the floral format of a Hydrangea is that cluster of fertile flowers that is surrounded by sterile bracts that give that gestalt of the lacecap look.

Q. So you’re wandering in the wilderness [laughter] either very far south or across the ocean, around the world, with colleagues who are savvy plant collectors with many years of experience.  And you see something that is in this genus, and you don’t dig up a shrub or a climbing plant to bring home. Do you wait to collect seed, or how does it or work? I’m assuming from what you are saying that these are traits—like the color red in flowers, or the evergreen foliage—that you might want to bring into the gene pool of breeding for future plants.

A. Right. Plants don’t work, and in fact from Asia itself you cannot bring a Hydrangea plant back in. It’s actually a restricted genus from plants, but not from seed. The collections of these plants are from seed, and just so everyone knows: I am limited to 50 seeds of any one collection.

So when you are talking about 50 seeds of a Hydrangea, you’re basically talking about the tiniest pinch of seed possible. You would barely be able to see 50 seeds of Hydrangea, they’re so incredibly tiny.

Q. So you climb every mountain and ford every stream in order to bring home a pinch of dust? Is this what you are telling me, Dan?  [Laughter.]

A. A pinch of Hydrangea seed, yes. But it’s a very efficient way to look at a wide range of traits. I can make a collection of 30 different individuals of the same species while I am on any one trip, and those grow those on, and they’ll be in blossom in two to three years, and I can look at the variation within those seedlings.

Q. Tell us about some of the species that you’ve collected, or are interested in—where shall we begin? You said something about interesting foliage, so maybe we should start with some that have exceptional foliage?

A. Let’s do that—because foliage first, right?

Q. Indeed.

A. So the aspera types, I think a lot of keen gardeners would be familiar with. But the group of asperas, those are the ones that are large-foliaged and generally feel very velvety—and in fact look velvety, sometimes almost like black-green in color, and demanding that you touch it. The asperas are very diverse, and to be honest that group is misunderstood—it hasn’t been sorted out. [Above, a large-leaf aspera type in bloom.]

Q. I’m misunderstood, too, so does that make me a Hydrangea? [Laughter.]

A. Yes, we’ve all known this for a long time. [Laughter.]

Q. I knew that. So it’s misunderstood and needs to be sorted out taxonomically?

A.  It needs to be sorted out. The nomenclature is incredibly confused and confusing, and that’s certainly one of my goals: to collect as many of these as possible and to get them better understood taxonomically, botanically. It’s not until we really understand something that we really know it, and that is one of my goals.

But in the process of doing that, I have come across some great garden-worthy plants. There are two species in that aspera Group that occur in Japan. Both of them are relatively obscure in cultivation, even though they are both highly ornamental.

One is a species that occurs only on Shikoku Island and than a couple of mountains on Honshu, and that’s called sikokiana. It’s represented in cultivation by only a couple individuals in North America, sadly enough, because it’s beautiful.

On the radio if I could say everyone visualize Hydrangea quercifolia with that jagged leaf and size, and then you add an arresting layer of felt to that leaf—that’s what sikokiana looks like [below]. So I have been working with that species and trying to work some purple color into that foliage, and that jagged edge.

Q. Have there been any introductions?

A. We just have our first seedlings that have some purple coloration in it, so that’s pretty exciting.

The other species from Japan is called Hydrangea involucrata, and that’s a fairly celebrated species in Japan itself, but in North America not so much. It’s unfortunate. The flowers emerge form these enormous, rounded buds—it’s so distinctive, they almost look like a peony bud about ready to burst. And they open and have a lovely lacecap appearance.

So those two would both be hardy in your god-forsaken climate.

Q. I’m a Zone 5—are you lording over me that you’re like an 8 or something? [Laughter.]

A. Yes, we’re an 8, but not that I want to rub it in. Too much. Not that I do.

Q. Thank you. Now aspera, which is in the trade and there are varieties available—is that like a Zone 7ish or 6ish plant? [Above, Dan’s introduction of H. aspera ‘Plum Passion,’ left, and a red-stemmed version he is working with.]

A. I always use Philadelphia as my hallmark for that, because I have seen what we call Hydrangea aspera Villosa currently–it won’t be called that forever—I’ve seen that grown successfully in the suburbs of Philadelphia. So I think that is Zone 6. I wouldn’t say we could go much further below that.

Q. But that’s a great one for people to look for now that give us some of that velvety, felted sort of leaf, right?

A. Absolutely. Beautiful foliage, plus just a fantastic floral display of lacecap flowers, bicolor pink and lavender. And you know Hydrangea sikokiana, the one I was telling you about from Japan, was growing as a beautiful specimen at Cornell in New York, so that’s fairly cold.

Q. What about serrata—is that another species you like?

A. I have a lot of affection for that, and just as I said about involucrata in Japanese horticulture, Hydrangea serrata—called the mountain Hydrangea—is a real classic Japanese garden plant. Forms of it have been collected for centuries, and because of that if you explore that species you’ll find countless numbers of cultivars with these beguiling Japanese names: ‘Shirofuji’ and ‘Jogasaki,’ all these lovely Japanese names attached to it. That is one of the hardiest of the hydrangeas because they occur all the way up in the mountains to 6,000, or 7,000, or 8,000 feet, and not only in Japan but also on the Korean Peninsula. [Above, H. serrata ‘Beni.’]

I had made one exception from collecting hydrangeas only by seed, and that was coming across a double-flowered form of that in the wild in Southern Korea, on a mountain called Chiri-san. There was a rooted piece—a rooted stem of that plant, kind of self-layered—and I removed that.

Because of course if you have a double-flowered form of anything, it doesn’t set seed so there wasn’t any opportunity to collect seed of that. So I took a rooted piece of that, and it’s now in the trade under the name of ‘Chiri-San Sue,’ a beautiful very delicate double pink-flowering Hydrangea serrata. I think it’s charming.

Q. So we’re going to look for that one [above]. I think I’ve read about the species angustipetala.

A. And that’s also very distinctive. We discussed the fact that a lot of people look at hydrangeas and don’t recognize them as hydrangeas in foliage, and that is certainly one of them that doesn’t have a Hydrangea look to it at all. It has a narrow leaf, almost glossy, and what I love about that species—which I have collected in the mountains of Taiwan—is that it’s the earliest-blossoming of all the species of hydrangeas in my garden. It will often be in bloom in my garden in late March and early April, so long before any other hydrangeas are setting bud, Hydrangea angustipetala is flowering and has what I think is a beguiling fragrance.

Q. Now that’s not common in hydrangeas, is it—a fragrance? [Above, Dan’s H. angustipetala ‘Golden Crane.‘]

A. That is not common but it’s not completely unknown, but that’s one of the best species to seek out for fragrance.

Q. Is that a possibility of a trait we may have more of? Is anyone breeding for fragrance?

A. To my knowledge not anyone other than my own very passive breeding program.

Q. Your mad scientist program over there in the backyard? [Laughter.]

A. It’s not too mad—it’s mostly letting the bees do the work, and me gathering the seed and seeing what I get in three years’ time.

Q. Where I live, in Zone 5 as you have pointed out to everyone, which is not in Zone 8…

A. [Laughter.]

Q. …in case people didn’t know that. Zone 5 is not in Zone 8. But here the paniculata, the panicle hydrangeas, grow lustily and really freshen up the heat-weary midsummer and fall garden with their giant white flowerheads. I love a couple of the oldtimers—straight paniculata and ‘Tardiva’. But now when I go to nurseries I get a case of the shakes because they have got like 400 billion paniculata varieties. I think actually there are close to 100 now—the last time I checked there were 80 or 90, and that was a few years ago. [Above,some of the panicle hydrangeas at Margaret’s.]

Are there ones that you love, because you really know this genus? Or can you just take them or leave them?

A. I’m probably like you: I look at that list and sort of go cold, primarily due to the fact that so many of them are selected for their dumpy, squat qualities.

Q. [Laughter.]

A. They want these short, squat things in one’s garden. And there is no question, that species is fantastic. I grew up with it as a kid—the old Pee Gee, Hydrangea paniculata ‘Grandiflora.’ You can’t beat it; you cut it down to the ground, right—and Zone 4 Michigan is where I grew up, if you think you had it bad.

Q. [Laughter.]

A. They’re beautiful. But now they’ve started selecting for all these very dwarf, compact varieties, and I think they’ve lost their grace. I’m sitting here in my office at Heronswood and looking out at three Hydrangea paniculata seedlings that I grew from seed I collected in the Japanese Alps, on Honshu, all the way back in 1997. Each one is different, but each one of them still possesses that wild, very graceful habit, with tall stems. To me, that’s what that species wants to be. It wants to be set free; it doesn’t want to be constrained into dwarfness.

Q. I second that emotion. It’s funny, I grow them really, really big—huge old ones, and to me that’s what they are meant to be doing, and they’re fabulous and I love them.

Before we run out of time, I want to just double back quickly to what’s going on with the climbers. What traits may be coming into our world, depending on what Zone we are in for the climbers? You said red flowers, evergreen foliage—what species are those?

A. There are so many different species. Hydrangea peruviana is a beautiful pink, and then there is asterolasia, which is from Central America, which is also pink.

We have three different evergreen species growing in our gardens here at Heronswood. One is Hydrangea serratifolia; that’s Chilean. Hydrangea seemanii is from southwestern Mexico. And then Hydrangea integrifolia is the only evergreen climber that comes out of Asia [above, in bud and bloom], and the only one we have from seed collected in Taiwan, but I have also seen it in Vietnam and China.

With the evergreen climbing hydrangeas, at this point we’re looking at Zone 7B and above—at this point. But what’s exciting is that all hydrangeas have the potential for cross-breeding with one another. If we can get these pink- and red-flowering species successfully into cultivation, and start doing cross-pollination with the old standard, Hydrangea anomala petiolaris—the climbing deciduous species—then we do have great potential for working color, like pinks and reds, into the climbing hydrangeas that are hardy all the way to Zone 4. So that’s pretty exciting stuff.

Q. You had better keep bringing back those pinches of seeds and doing your little experiments over there.

more from dan hinkley, and how to visit him

• The Heronswood garden website, with visiting details
• Dan Hinkley’s personal website, including event listings for Windcliff, Dan’s home garden
• Dan’s plant introductions with wholesaler Monrovia Nursery

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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its seventh year in March 2016. 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 August 28, 2017 show right here. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

(Photos from Dan Hinkley, used with permission.)