fern secrets, fern sex and fern gardening, with tony avent
THERE IS NOTHING–and everything–new about ferns, ancient plants that have lately been getting breeders’ increased attention. Yet how many of us really know how to use ferns effectively, or can even ID more than one or two kinds? Tony Avent of Plant Delights Nursery in Raleigh, North Carolina, can say yes to both questions, with almost 1,000 fern taxa in his collection, and extensive gardens where ferns play key roles.
Ferns have been on the planet for more than 300 million years—about twice as long as flowering plants—and in recent years breeders with sophisticated eyes have introduced extra-showy varieties for our gardens.
No wonder there is a focus on ferns, since they are naturally deer-resistant, mostly adapted to shady gardens, and hey, you don’t need to deadhead them since they’re not flowering plants. You can’t attribute any of those qualities to, say, a daylily.
On my radio show and podcast, Tony treated me to a 101 on ferns and how to use them in the garden (that’s a tiny section of the 28-acre private nonprofit Juniper Level Botanic Garden, below, which he founded in 1988). Our chat included some of his favorites, propagation how-to–and we even covered fern sex, ferns wearing petticoats, and other trash talk, lest you have the mistaken impression that ferns are boring because they are so old.
Read along as you listen to the March 2, 2015 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).
listen/read: fern q&a with tony avent
Q. Do you remember the first fern you grew—or maybe the first one you collected on a plant-exploration trip? How long have you been into ferns?
A. I probably collected my first ferns at 6 or 7 years old. It’s been awhile, but I remember it—it’s like remembering where you were when important events in your life happened.
We had some woodlands near our home. The first two I collected were the Northern maidenhair fern, Adiantum pedatum, and the wonderful evergreen Christmas fern, Polystichum acrostichoides [below left to right, respectively].
Q. And those are two very familiar ones to me, even though we’re not in the same place. They’re pretty widespread.
A. Exactly. It’s incredible that two plants can have such a range. I’ve actually found Northern maidenhair fern as far south as central Louisiana—and it’s the very same plant. Typically you think if one plant grows in the North it won’t grow in the South—but this plant has an incredible range.
Q. And the Christmas fern as well?
A. About the same range, from the Gulf Coast all the way up into the Northeast.
A. That’s what I hear.
Q. Or have a lot of fleece outfits that you can wear. [Laughter.]
Can you give us a brief fern glossary/biology lesson—because they really do have a somewhat distinct language from flowering plants. Let’s start from the bottom up—roots, and rhizomes….
A. Of course we know what roots are—we have those in almost all our perennials. But a fern’s stem is actually underground, or right at the ground. It’s called the rhizome, or crown; ferns don’t have a stem like ones that we normally know of.
The leaves are composed of two parts: the top part is a rachis, and the bottom part is a stipe. The fern leaf itself is called a frond. When the fern gets ready to reproduce—well, ferns are a little odd in how they do so.
Normal plants produce a flower, they have sex, they produce seed, you plant the seed, they come up.
Ferns evolved way before plant sex was invented. So ferns created these little things on the backs of leaves called spores–basically fern seed. They’re hidden in this little capsule called an indusium. Now, people see these on the backs of the ferns and they call us and want to know how to kill them because they think there are pests on their fern fronds.
But the fern is trying to have sex; leave it alone.
Q. Give it some privacy! [Laughter.]
A. Give it some privacy—a little darkness, a little Barry White, and you never know what will happen.
Q. It’s interesting because when ferns evolved several hundred million years ago, it was a watery world compared to today. Things had to move around in that environment, even these dustlike spores.
A. That’s why most ferns can only have sex while they’re swimming. [Laughter.] A little-known secret about ferns: When those spores are ripe, they fall on the ground, and then they actually germinate before they’ve had sex—it’s the only plant that does this.
Then they create this substance that looks like algae or maybe a moss, and in that there are males and females. They hide on the underside of the leaves, and sit there waiting for a swim—for the males to swim around to the females. And the next thing you know, you’ve got a fern leaf popping up.
Q. And I think I know the words for that: motile male gametes.
A. There you go; I’m impressed.
Q. Tony Avent, I can keep up with you in a few of these things, but not most. [Laughter.] But the cycads have that, too—those ancient plants have motile male gametes because it was a watery world.
So we have our rhizome—and it’s the stem, but not a stem standing up like in most plants. And we have the rachis—the midrib of the leafy part—with the stipe below that, connecting to the rhizome. And we have indusium filled with spores—those little packets on the back of the fronds.
I saw that the American Fern Society has a spore exchange (of course it would!) and also that at Plant Delights you grow many of your species from spores, so I have to ask: How does this work, when you swap spores?
A. If you just let the spores fall, most ferns are not going to come up particularly well. You might have 10,000 spores fall and if you’re lucky you might have one plants come up. So you really do need to gather them.
The key is to simply know when they’re ripe. When they start turning brown, I tell people to take a magnifying glass or a hand lens and look. You have to catch them before they disperse, because the indusium actually opens up and many of them will explode out. We put them on the microscope, and they actually start shooting all over the room, so it’s really sort of neat—unless you’re a clean freak.
Once we gather those, we take the leave, or fronds, and put them in an envelope for about a week, and that lets all the spores fall out in the envelope. Then we dump out the fern leaves, and that leaves just the spores. That takes really good technique, because the chaff that’s left looks really a lot like spores.
We dump that in a pot of very finely ground moist soil, and we seal it up in a zip-lock bag.
Generally two to three months later, they come up—you’ve got that algae—and you need to open the bag and let them go for a swim. You open the bag, dump a cup of water in there, and slosh it around—and they have sex while they’re swimming.
Q. Fascinating. So you simulate what would have happened in ancient times.
A. That’s the way it works.
Q. As I said in the introduction: I don’t think gardeners are confident with using ferns, nor do most of us know how to ID many species/varieties. So let’s change that:
First, tell us some of uses you put ferns to in your gardens.
A. For me, they’re the textural break that makes a garden work. Especially in a shade garden, you tend to have a fair amount of bold-foliage plants. You’ve got hostas, the hellebores—the textures tend to be more bold. So I like the light, airy texture—it tends to make all the others work together, like using ornamental grasses as a texture break in the sun garden.
That’s where ferns are so great in the woodland garden—as well as in the sun garden.
Q. So we might use them in drifts that way, or as an exclamation point. I love big, bold, tropical-looking foliage plants—even though I’m in a short-season Zone 5B with cold winters. So let’s talk big ferns.
A. Ferns come in everything from very tiny to very large. Typically the larger ones tend to grow further south, and are more tropical. But we’re always looking to find new and different things for different climates. [Above, left to right, two 6-inch-tall ferns, Adiantum venustum and Polypodium vulgare ‘Uulong Island.’]
Q. For example, the Goldie’s fern, Dryopteris goldiana—that’s a bigger, bolder-looking one, even up North here.
A. It can get up to 4 feet tall, yes, and makes a beautiful bold texture for the very cold areas, and it will go up to probably northern Minnesota.
Q. It definitely grows here in Zone 5, and you don’t need a big mass to make an impact.
A. One clump will bulk up and get quite nice.
Q. You said “bulk up,” and “clump”—and there are some ferns that do the opposite, like the ostrich fern.
A. Ferns come in both runners and clumpers, yes, depending what you’re looking for.
Ostrich fern is a very common fern up in the Northeast, and generally not seen very much down South, because it typically doesn’t like hot climates. But we’ve got a variety that does well in both hot climates and up North.
It’s called ‘The King,’ Matteuccia struthiopteris ‘The King’ [below]. If you’ve got a moist area, it will cover 20 or 30 feet; it makes a huge mass. You can slow it down putting it into a drier area with more competition.
Q. The ostrich fern is classic fern to me; there’s something romantic about it. And it has persistent fronds, the fertile fronds, even in winter—after the herbaceous part dies back to the ground. [Above, fronds in season and fertile fronds in winter.]
A. I talked earlier about how most ferns put their spores on the back of the leaf, but ostrich ferns said, “Nope, we’re not going there. We want to do it differently. We want to produce fronds that are really nice without any spores, and then produce separate fronds that only have spores.” That’s called a dimorphic fern—meaning it has two different types of leaves.
The beauty of that is in the middle of winter, when the snow is out there, these wonderful ever-brown fern spore stalks are there, and they’re incredible.
Q. To me it’s a fern that gives you a lot more interest in the garden. When it begins to show in the spring, it’s another classic, almost primeval, fern moment, with those fiddleheads coming out of this brown, hard, knobby thing at the ground level. It’s preposterous that these things come out of it—it doesn’t even look alive.
A. It’s like little green zombies popping up out of the ground. It’s fascinating—in spring you can just go out and watch them rise up, like a giant hand coming out of the ground.
Q. How big does ‘The King’ get?
A. For us 3 feet tall. If you had a cool, moist area, you could probably get 4 feet out of it.
Q. And it spreads like the species?
A. It does indeed.
Q. I have a few little “issues,” shall we say, where it’s going into the lawn, but someday I’ll get after that with my shovel.
A. It’s nice to plant them near a lawn where you can mow them off. You certainly do not want to plant ostrich fern near some expensive woodland plants, because it is just way too aggressive.
Q. Other big, bold ferns?
A. Dryopteris australis [above left], Dryopteris ludoviciana [above right]—all great native U.S. ferns. Even with the name australis—in this case, that just means it was from the South. The botanist who found it was from New York and he found it in North Carolina, so he names it australis, which is a little confusing.
Both of those are in the 4-foot range, and they can tolerate soils that are dry, or tolerate standing water—it’s an amazing group of ferns, the Dryopteris.
Q. I recently learned that there is climbing fern.
A. Lygodium japonicum probably wouldn’t be hardy up in your area, but where the winters never drop below zero, it will grow up to 10 feet tall and climb up a trellis. It dies totally to the ground in wintertime, and then back up again next year.
Q. One fern most people probably recognize is the Japanese painted fern, Athyrium niponicum ‘Pictum.’ But as always, in the PDN catalog, you go beyond the basic one, and have a lemon-splashed Athyrium [above left], ones with petticoat frilled edges, and so on. [Including larger ‘Godzilla,’ above right.] Seems like a lot of breeding work has been going on with these plants.
A. It really has. Athyhrium niponicum is a Japanese native fern, and it’s really prized because the leaves can have colors ranging from greens to silvers to purples. So there are many great selections.
We have a couple of selections with incredible cresting, as you mentioned. Cresting is something that the Victorian-era collectors were really fond of. They looked for every crested form. We’re trying to find the same cresting in the new ferns.
Like little petticoats—it’s an extra gussied-up look. For people who like their ferns a little on the trashy side. [Below, the crested Athyrium ‘Ocean’s Fury’ and ‘Thrill Seeker, left to right.]
A. You mentioned the bright yellow one, called ‘Lemon Cream,’ a selection from Japan. The leaf comes out normal green, but as the summer goes on it starts developing bits of yellow, and by the end of the summer it’s almost entirely yellow. An amazing variation on the Japanese painted fern.
Q. There are some standout American native ferns in the genus Athyrium, or lady ferns, aren’t there?
A. The most common one people know is Athyrium filix-femina, but the interesting thing: it’s not just native here—it’s also native to Europe.
Q. I didn’t know that.
A. There are forms that are U.S.-native selections, and forms that are European selections. The cool thing about fern spores: They’re so light, they literally blow around the world. Hundreds of thousand of years ago, they went around—so you can find the very same species in some cases, like some of the maidenhair ferns, on every single continent.
Q. So they weren’t dependent on the movement of animals, or birds, to move heavy seed around, like with many flowering plants.
A. A fern spore gets up there in the atmosphere, and hops to another continent.
The one called ‘Lady in Red,’ is a selection made in the Northeast, and then there’s a really nice one called ‘Victoriae,’ [photo in box at bottom of the page] and that’s a selection of the European form of Athyrium filix-femina.
Q. Is ‘Lady in Red’ the one with the colorful red midrib?
A. It is. And we have a Southern form of that that we introduced last year, called ‘Red Neck Girl.’
Q.[Laughter.] Of course you do, Tony; of course you do. You just couldn’t help yourself; irrepressible.
A. One I really like is Dryopteris sieboldii [above left]. It’s actually hardy to minus 10, but it looks very tropical, with very wide fronds unlike any of the other Dryopteris. And then Dryopteris uniformis, one of my favorites, which has petticoat-like cresting [above right], and will take down to minus 20. That’s just a beautiful fern in the garden; a stunning fern.
Q. How many kinds of ferns do you really have?
A. Just under 1,000 taxa. We had a really nice visit a couple of years ago from the British fern society, and I think it was neat for them to see a collection like this in the U.S. Generally you have to go to Germany to see a really big collection.
Q. The biggest one in this country?
A. According to them, yes. They actually said it’s the biggest in the world—but I haven’t visited all over the world to see every fern collection.
Q. Not yet—but there are many such adventures ahead by Tony Avent, correct?
visit plant delights (including this weekend)
PLANT DELIGHTS and Juniper Level Botanic Garden in Raleigh, N.C., are open for visitors, and shopping, on select Fridays, Saturdays and Sundays each year–including the weekend of March 6-8, 2015, and again on some dates in May, July and September. Get the schedule to plan a visit. (That’s Athyrium filix-femina ‘Victoriae,’ above.)
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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 March 2, 2015 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
(Photos from Plant Delights Nursery. Used with permission.)