I GET ALL PANICKY when people say something is a “rock-garden plant,” certain that they mean it’s miniature and precious and finicky–a.k.a. something I’ll kill. But whenever I have visited a rock garden, whether at public spaces like the Royal Botanic Garden at Edinburgh, Scotland, and New York Botanical Garden, or a private garden on a home scale, I’m so drawn to what I see.
Now Joseph Tychonievich, the sought-after Michigan-based garden writer and author, has confidence-building advice for me in his just-out book, “Rock Gardening: Reimagining a Classic Style.” Joseph is also author of “Plant Breeding for the Home Gardener.”
Read along as you listen to the Oct. 24, 2016 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).
my rock-garden q&a with joseph tychonievich
Q. How did you get the rock-garden bug? Did you catch it in your time working at Arrowhead Alpine Nursery or how?
A. Yes, mostly through Arrowhead Alpines, which is a rare-plants nursery near me in Michigan. I started going there just because they had cool plants, but they specialize in alpines, and once I was looking around and seeing them, that’s where I got the bug.
It started there just when I was a customer, and then when I was working there and propagating the plants and growing them, that when I got more deeply interested and excited about rock gardening.
Q. Are you a member or NARGS, the North American Rock Garden Society? Tell the truth. I mean, it’s a pretty serious bunch of plant people, traditionally—I’ve seen notices for lectures at meetings on topics like “Alpine Flora of Greece” and “Chinese and Himalayan Plants for the Garden” and such [laughter].
A. I am a member—it’s actually the only plant society I’m a member of, because they have an amazing seed list. You can get incredible seeds from them. And they have a quarterly magazine really—the quarterly newsletter for members is great, with great articles.
It is a fun group and I love going to the meetings, though I am often on the road on weekends when they are meeting. Rock gardeners typically are people who love all plants. I get really tired of the hosta people who only want to grow hostas, or people who only care about tomatoes, but rock gardeners I feel love everything, and they feel rock gardening is the place where they can grow the most little stuff and cool stuff in a small area.
Q. And I tease about NARGS, because really the keenest and most acclaimed gardeners I know are members for life, and have been going to meetings forever. There are chapters all over the place, and it’s not like cute, fun, outdoor-decorating topics—it’s real plantsmanship, and that’s great.
The NARGS website says: “Gardens in which rocks and plants appropriate to them are the chief landscape elements are called rock gardens.” I’d say a rock garden, “is a place (with rocks of course) where obsessed people try to grow very difficult plants.” [Laughter.] How does Joseph define “rock garden”?
A. I kept asking myself that when I was trying to put this book together. To me a rock garden is a style of gardening inspired by what we see on mountaintops. On mountaintops you get these alpine plants and the plants get shrunk down very small, and have these beautiful compact forms, and you have the stones. And the plants often have these huge flowers because pollinators are scarce up there are you need a big show to attract pollinators.
Q. Oh, that’s why. I didn’t know that.
A. So you get this very distinct form to an alpine plant, and often you get similar forms that are not on mountaintops. Obviously I don’t garden on a mountaintop [laughter]—that would be fun—but taking that inspiration of what you’d see in those settings, and the aesthetics of it, which is so much what appeals to me about rock gardening.
The styles of gardening—the trends for a long time—have been very full and lush; big containers full of annual in full bloom. Rock gardening is such a different look. It’s leaner and more about the form of the plants, and the spacing of the rocks. It feels very fresh to me, compared to the aesthetics that have been dominating the trends in gardening.
Q. You said the word “alpine” a couple of times so far. Can we—or should we—distinguish between alpines, plants that come from a tougher higher-elevation situation and other rock-garden plants?
A. A true alpine plant would be one that’s native to higher elevations, usually above the tree line. Rock-garden purists would grow alpines. I’m not a purist, and I like to grow lots of things that are not true alpines but have that same kind of look—something small and compact that will look good with my rocks. So I’m definitely an “all of the above” rock gardener. I like to grow miniature hostas, which are not an alpine by any stretch of the imagination, but beautiful in a shady situation.
Q. There are a lot of styles of rock gardens profiled in the book. Some are very modern and stark; others are old-fashioned and dripping with lichens and historic-looking places.
There were two styles that I wanted to shout out because I thought, “I can do that,” but I didn’t know about them. One was called a crevice garden. Can you explain it?
A. Crevice gardening is a style of rock gardening that came out of the Czech Republic. The Czechs are huge rock gardeners. In a crevice garden, the idea is taking thin pieces of rock—the kind of stones you might use as pavers—and then setting them vertically or nearly vertically in a container or in the ground, so you have thin layers of soil between these flat pieces of rocks.
Q. These are almost upright rocks, and they’re partway out of the ground?
A. It’s almost like a layer cake with flat rocks and soil between them, and then you have these narrow crevices—the soil between the rocks—which is what you put the little plants in.
It’s a beautiful style because it’s different from what we’re used to seeing. It’s also a really cool way to grow them, because those flat rocks guide the roots down so they get rooted very deeply, which makes them often easier to grow in those conditions. They’re a little more drought-resistant, because the roots are down there where it’s cooler. It’s a really great way to grow the more difficult rock-garden plants, and is beautiful and interesting as well.
Q. And again, what I saw was that if I had semi-thick flattish rocks—it almost looked like an accordion file of stones.
A. That’s a good description.
Q. The tops of the “folders”—the rocks—are sticking out of the ground, but I can tell that a lot of the rock is buried. Like a series of folders with space between them, and I thought: “I can do that.” I could get stone at the local stone yard, and create a place like this even in my non-alpine, non-top-of-mountain place.
A. And you could even do it in a container, with just a few rocks. One of the gardens that I profiled is a rooftop garden in Manhattan, with a very small space, of containers. Because the alpine plants are small, you can do a lot of them in a very small space, and fit in really cool plants without a big piece of garden real estate.
Q. I loved that you are creating your own crevices by placing the rocks in this manner. And then there was a scree garden, which appealed again because it looked like something I could do. Tell us about what a scree garden is.
A. There is a geological definition of a scree, which is like a rockslide, where gravel and stones have tumbled down and it makes an area of loose rock. But the garden version of the scree is that rather than adding big chunks of rock, you’re building up a layer of coarse gravel and sand. Rather than having to create a whole miniature mountaintop of big rocks in your garden, having a layer over your regular soil of gravelly, sandy soil gives you that really sharp drainage that a lot of the alpine plants need.
That’s one of the keys: Rock-garden plants have a reputation for being difficult, some of them, but often it’s just that they need specific conditions, and usually what that is, is good drainage. They’re native to these rocky soils, so just by giving them that layer of good drainage, you can grow a lot of things that would be difficult otherwise.
Q. Of course I want a trough garden, but I want those authentic stone troughs from a historic estate in the UK, those massive things that are beautiful and aged. So I want one of those. [Laughter.]
A. Yeah, wouldn’t we all?
Q. You were talking earlier about how you could work with containers and do a small grouping of troughs and that could be your “rock garden.”
A. The traditional troughs are these beautiful stone containers, but you can turn any container into a rock-garden trough garden. Again, because the plants are so small, even in just a few little containers you can really get a nice collection of interesting things—whether it’s Sempervivum, the hens and chicks, which are easy, or you want to go toward collecting Draba, which are more unusual. You can do a lot in just a collection of containers.
Q. Let’s talk a little about plants. There is one in the book that I shrieked when I turned the page. It’s called Physoplexis [above]. It looks like it’s something from under sea or on the moon maybe—fabulous, with its own spectacular geometry. But is that one of the ones I maybe shouldn’t start with, right? [Laughter.]
A. That has not been an easy one for me. I think rock gardening really gives you the most diversity of plants to grow—there are so many things you can put in a rock garden. They range from the very difficult, elite things that people compete over growing to perfection, like what you just mentioned, on down to the sedums and hens and chicks that are very easy and adaptable, and won’t require a lifetime study to get right.
Q. In order from beginner to intermediate, suggest a few I should start with. I think I saw on your Facebook page some Orostachys, for instance.
A. Sempervivum are the hens and chicks we’ve all seen growing in old boots [laughter]. And then there is a closely related genus called Orostachys, which is just as easy to grow, but I think has a bigger range of foliage colors and patterns. Some of them have very beautiful silver-blue foliage; some have a browner look to them.
They almost can mimic the look of some of the tender succulents that have been so trending now, like Echeveria, but they’re extremely cold-hardy and easy to grow, just like the hens and chicks.
Q. Very sculptural and fascinating-looking.
A. Again, such a different look, which is why succulents have been trendy for a while—the sculptural look and their leaves. That look has really come out of Southern California with all these tender succulents, but there are a lot of great winter-hardy succulents, though most of them need good drainage. If you give them the good drainage of a rock garden or trough container, it really lets you grow a wide range of hardy succulents.
Q. What are some other “gateway” rock-garden plants for me to consider?
A. I really love the genus Erodium [above, E. chamaedryoides], which is one that’s not well known, but is really easy. It’s in the same family as geraniums and pelargoniums, the annual geraniums. They’re really beautiful little, very compact plants with gorgeous ferny foliage and then small flowers in pinks and purples and whites that look similar to your hardy geraniums.
But they’re really easy to grow. As long as they have sun to part sun, and they’re not sopping wet, they grow easily. The leaves look great all the time, and they kind of bloom throughout the summer. They’re not just a spring thing, but give you this long season of bloom, which I really appreciate in the garden.
Q. They really do look like little baby perennial geraniums—the flowers especially.
A. One of the charms for me of rock-garden plants often is that it’s the miniature version of something you already know—like there are miniature versions of Gypsophila, the baby’s breath. The standard one is this huge, billowy perennial, but there are ones only an inch or two tall. It’s somehow fun to grow something that looks familiar, but is in this different miniaturized form.
Q. It’s that same-but-different thing; familiar, but also unfamiliar, and visually arresting. You feel like you know it, but you also don’t.
I’m assuming all these plants we’ve discussed so far are in a sunny environment, yes? We’re not talking about tucking things into dark, moist spots.
A. The classic rock garden is in sun, because the classic rock-garden plants are from sunny areas. But you certainly can do them in shade. I’ve seen some beautiful ones with miniature hostas, and Ramonda. There are a few plants that will do that, but the bulk of the rock-garden plants are for sun.
Q. What’s next in our palette?
A. We’re talking about same-but-different, so it’s also a place to grow a lot of bulbs. Things like species tulips, species crocus, species daffodils, some of the bulbous iris like Iris reticulata. There are a lot of these really tiny bulbs that are native to rock-garden conditions. They want a dry soil, especially in the summer, when they are dormant. And also those really tiny daffodils and miniature species tulips—when you put them in the open garden they just get lost. You don’t see them with all these other plants towering over them.
They’re great to add in, and will love the rock-garden conditions. By putting them up in a trough or somewhere you can really highlight their beauty; you can really appreciate how they look. And a miniature daffodil is just as easy to grow as a full-sized one, and will love your rock garden.
Q. Shall we go to some intermediate-level plants? Dare we? [Laughter.]
A. I’m going to make a pitch for daphnes. They have a reputation for being difficult, but part of the reason I love them is that they grow better for me than I saw them in England.
Q. Well, aren’t we just very full of ourselves? [Laughter.]
A. I took a trip to the UK to photograph gardens for this book, and ended up just feeling inadequate and jealous.
Q. Yes, I understand.
A. So the daphnes were the one thing where I could salvage a little pride. [Laughter.] They did better here—they like warmer summers and a more continental climate like we have in most of the U.S.
Daphnes are shrubs, and the alpine ones are miniature shrubs, like a little bush. Some of the smallest ones are only a few inches tall. Some are evergreen, with beautiful, fragrant flowers.
They are easy as long as you give them good drainage. If you put them in a heavy, wet, clay soil they will rot out and die. Put them in a raised bed with a sandy, gravely soil or in a container, and they’ll be tolerant of drought and heat. Rabbits and deer don’t eat them, and the flowers are just incredible.
Q. I only grow a couple of species, and they’re not rock-garden kinds, but the fragrance of the flowers—there is nothing like it, as you say.
A. It’s incredible, and with the rock-garden ones, the first flush of bloom in the spring will completely cover the foliage, a solid sheet of pink or white flowers. The bloom is unmatched. And the alpine ones will often rebloom in the summer. Often when we have a hot, nasty summer and everything is looking wilted and dry, my daphnes are coming into another flush of bloom and that’s nice to see when everything else looks miserable. [Above, D. cneorum blooming in October at Denver Botanic Gardens.]
Q. We have some cracks and crevices and pockets, whether we’ve created them ourselves by putting rocks in a particular order or have a natural place for this garden. Or maybe I have a stone wall, and I want to put some Orostachys or Sempervivum in it. How do you engineer that; how do you tuck them in and get them started in touch spots like this?
A. One thing that you want to start with small plants. Often when we go to the nursery, we want to get the biggest pot and the biggest plant for our money. But if you are planting up a small crevice garden, you really want to buy small sizes. With a Daphne, for instance, it might just be a rooted cutting.
The other thing is not to be hesitant to remove the soil from around the roots of a lot of these plants. Often what you are going to get from a nursery is a standard peat-based potting media that is going to hold a lot of moisture around those roots, which is not what these plants want.
I often bare-root them or nearly bare-root them, so that it makes it easier to slide them into a small area, and then put back in the soil media I’m growing them in in the garden—which is going to be a drier, sandier one.
Q. That may be the mistake that I have made is leaving on the potting soil, which then probably becomes a sodden little spot.
A. Right. If you put a little plug of peat in your sandy soil, things can rot out pretty easily.
Q. Everybody loves the color of gentian—the blue color. In my whole life, I’ve never tried anything in that genus, though. What’s the beginner gentian—is there one?
A. There absolutely is. The acaulis ones are difficult. But there are two species, Gentiana septemfida [above] and Gentiana paradoxa, that are actually fall-blooming species, and they seed around for me in the rock garden. What you actually get are often hybrids between the two species.
They want good drainage but are not picky about it, and they make a stem that’s maybe 6 or 8 inches long, and they kind of trail and weep, which is lovely at the edge of a trough. As the name septemfida suggests, around September there are beautiful true-blue flowers. I love blue, and especially in the fall when everything else is orange and red, when it’s nice to have that contrast of the rich blue color.
Q. So there are some gentians that I can try.
Q. I’ve always been, “Keep me away from those; I’ll kill them,” like I said at the beginning. They look scary because they’re so beautiful, and so I’m sure it’s unattainable.
A. Even the hard ones are not as hard as their reputation. I have a friend who grows lots of them in Iowa, which is not a soft and easy climate.
Q. Iowa: the rock garden capital of the world? [Laughter.]
A. Often we try to put them in too-heavy soils, when they want good drainage.
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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 Oct. 24, 2016 show right here. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
(Photos courtesy of Timber Press and Joseph Tychonievich. Disclosure: Purchases from Amazon links yield a small commission.)