seeds, cuttings, divisions: making more plants as spring approaches, with ken druse

THE DAYS ARE longer and the light is strengthening—triggers that don’t just start to wake up our plants, indoors and out, but also get us gardeners going. The signals have my propagation-mad friend Ken Druse starting more seeds each week and looking around the landscape and the houseplant-filled sunroom for some chances to make more plants, his favorite pastime.

Ken is author and photographer of 20 garden books, including one on plant propagation, and is a daring plant propagator himself. Together since 2021, we’ve co-hosted the Virtual Garden Club, a series of online classes about our favorite subject: plants. Ken gardens in New Jersey, mostly in the shade.

Read along as you listen to the March 20, 2023 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).

making more plants, with ken druse

Margaret Roach: Hello Ken, over there in the shade [laughter]. How are you?

Ken Druse: It’s a little dark, Margaret. How are you?

Margaret: I don’t know. I don’t know. What season is it anyway, this year?

Ken: That’s a really good question.

Margaret: Yeah. I’m totally disoriented, since the beginning of the… Well, the whole winter, and since the beginning of the year especially.

Ken: I know we talked about it, but four weeks ago I cut the ratty, awful foliage off the hellebores, and no flower buds were showing [below], and now they’re in bloom.

Margaret: Yeah. It’s crazy.

Ken: Right.

Margaret: Yeah. No, it’s crazy. It’s completely crazy. And same here. I’ve never seen anything like it. And then it’s four degrees, and then it’s 62 degrees [laughter].

Ken: Yeah. And you’re not kidding. That really happened.

Margaret: Yeah. It went minus 14, and a week later, 60, or 57 or some crazy thing. I mean, it’s just nuts. Whatever. Anyway.

So that’s getting us looking around the garden at opportunities for “Making More Plants,” as your book of about 20 years ago was called. And also I guess as I said in the introduction, I’m noticing in my houseplants, some of them were even ahead of schedule. It’s weird. It’s just so weird out.

Ken: Yeah. But I love it when the daylight hours start lengthening, and the plants always know, even the plants under lights that aren’t even near a window, they know. Some things that I’ve tried to propagate from cuttings, like a begonia or something, they’ve just rotted and were horrible, but now they want to wake up.

Margaret: Yeah. Absolutely. So what are some of the things that you’re eyeing around house or in the cellar or wherever you have things stashed or awake or whatever?

Ken: I can’t believe what a busy time it is. Mid-March is kind of the last time for major pruning, so I’ve been doing some things like that outside. And because you encouraged me, I did some experimenting.

Margaret: Uh-oh.

Ken: The bald cypress, it’s called bald because it’s deciduous. It’s a conifer, like a pine tree, except it drops its needles. And I cut it back right to the trunk, because it sprouts from the trunk every year. And it was supposed to be this really little dwarf, and now it’s 15 feet tall. So I thought, I’m going to make a column. So I did that, and that’s kind of scary [above, Taxodium distichum ‘Peve Minaret’ after its hard pruning]]. It’s not exactly propagation, but I know you and I are digging up our Eucomis bulbs, or I am anyway.

Margaret: And so when you say digging up, they’re in pots where?

Ken: They’re in pots. Right.

Margaret: Where do you keep yours in the winter, these pineapple lilies?

Ken: In a cold part of the cellar that goes down to… Probably coldest it goes to, maybe 20 for a couple of days. But usually it’s about 30 to 40 degrees. And I’m going to dig them up, and divide them if they can be divided, if they have little side bulbs, and re-pot them. Because they slowed down on their blooming, and I think they just need a little refreshment.

Margaret: Yeah. I find with the pineapple lilies that they make a lot of offsets. And so when I take them out of their pots, like you were saying, when they slow down, what I find is if I then un-pot it the next season after a disappointing bloom, there’s too many bulbs in there. You know what I mean? It’s just too crowded.

Ken: Got crowded. Right.

Margaret: And so I’ve started doing it every other year, making it more systematic, when they’re confined to pots, rather than wait till they fail a year. They always make beautiful foliage [above, ‘Sparkling Burgundy’].

Ken: You’re ahead of me.

Margaret: And they always make beautiful foliage anyway, so I like them anyhow. So that’s a good idea actually, to get on that now, that dividing, and making… And if you don’t have room or use for the extras, give them to friends. But that’s a good idea to do that now, because when spring-spring happens, there’s not going to be time for any of this. It’d be good to check some of these things off the list.

Ken: There’s such a list.

Margaret: Yeah. No, I know.

Ken: But we should say that pineapple lilies are called that because the flowers look like pineapples. They have little green leaves at the top of a long, tall flower spike. We love them. They’re so easy and beautiful.

Margaret: Yeah, they’re wonderful. They’re wonderful. And it just makes for “annuals,” things to put in your containers that you don’t have to buy every year and are unusual looking. And as I said before, the foliage is nice, frequently it’s freckled or speckled with splashes of purple. Some are all purple foliage. And then even the stems sometimes almost look like spots of an animal’s pelt [above, at Margaret’s, E. bicolor foliage].

Ken: I was going to say, leopard.

Margaret: Yeah. They have that animal-skin kind of look, that spotted-leopard look. Quite wonderful.

Ken: And people in warmer climates can grow them outdoors.

Margaret: Yeah. Like zone 7 and so forth, a lot of them. Yeah.

Ken: There’s a lot of things that, as soon as the ground is workable outside and not too wet, I’ll be digging them up and dividing them. You know how they show in books two spades back to back prying apart a plant? I never do that. It seems to damage them. So I usually dig up the whole plant, put it on a tarp, take my dedicated serrated knife, and cut them apart. So I’ll do that if there’s a congested hosta, or if I just want more of that hosta in another place, kind of an echo, I’ll dig it up and cut it in two to four parts, as long as each part has a growing point or an eye.

And Siberian iris [below], the middle of them die, so every, I don’t know, three or four years, I have to dig those up. But then you don’t get four plants, you get 24 plants.

Margaret: Yeah. And really that donut hole in the middle is dead stuff, and you throw that away. Yeah.

Ken: Dead, right. And all the outside stuff slows down the blooming and everything.

Margaret: Yeah. Again, if there’s time, because this is a freakish year in a lot of parts of the country, weather-wise, if your late winter allows you to safely be going around outside—if it’s neither snow covered or slippery or mucky, where you’re going to damage the soil—getting a jump on some of these things like we were just talking about.

Like we think of dividing… and so we are both in the Northeast, and so we think of a lot of time doing that in April into early May and so forth. But by then you have foliage pushed up, and you have flower stems or the beginning of them pushed up, and moving the thing without damaging it is harder. So you’re saying go ahead, be brave, do it a little earlier. It’s not like we’re going to have a deep freeze, 3 feet of frost in the ground again or something in March or whatever.

Ken: Right. As long as you know where the plant is, and maybe if you’ve marked it and thought about it. You can divide things that have… and you can even cut some things back and divide them later, but it will affect the blooming. So if you dig up the phlox when it’s 12 inches tall and cut it back to 6 inches, it’s going to still live, and it’s going to bloom. It’ll be shorter and it’ll be later. But I’m just saying, because you shouldn’t just give up because you’re getting a little behind, I would say.

Margaret: No, not at all. But on this end of the season, again, not when the ground’s still frozen, and not when it’s mucky and so forth, but as soon as you can, it’s O.K. to go around, like when you’re planting those peas [laughter], it’s okay to go around and look and see if there’s a few things that might be ready to divide a little earlier than usual.

Ken: Or move.

Margaret: Right.

Ken: I’ve got a list of things that… I do. I have things-

Margaret: I’m teasing. I have like 2,000 of them that need moving [laughter]. It’s horrible.

Ken: And some things… I’m moving a dwarf Hydrangea paniculata that has red flowers, and I’m moving it across the garden to a place where there’s a red-leaf peach and some other red things, so I’m moving that for aesthetic reasons.

Margaret: Right. So it’s not because it’s too big for the space or whatever. It’s a design choice. Right. So what other things were… We were talking about the bulbs, and actually I have other bulbs or bulb-like things in storage in my cellar. I have a lot of… What do they call them? Voodoo lilies, Sauromatum and other crazy… Amorphophallus and so forth. Crazy things that…

Ken: Stinky things [above, the flower of Sauromatum venosum at Margaret’s].

Margaret: Stinky. And some of them are awake. If I leave them in their pots, they wake up in January, February sometimes, and I’m like, “Uh-oh, don’t do it, don’t do it, don’t bloom. It’s going to stink. It’s going to smell like a dead animal in the basement.”

Ken: And then you have to give them light when they start pushing their leaves after that.

Margaret: Yeah. So there’s other things that I have stored that are going to be divided and “making more plants,” like you always say. But what other things are you eyeing for propagation projects now?

Ken: We can talk about seeds in a few minutes, but I mentioned the begonias, which is kind of a softwood cutting. They’re not even wood. But this is the end of the period for hardwood cuttings, which are cuttings from woody plants like shrubs. And they’re made when the plants are still asleep. And I think the last ones to make are cuttings from willows. Some people do dogwoods, too, those twig dogwoods and the willows that we grow, either pussy willows or willows with colored sort of foliage.

Margaret: Yeah. Sort of shrubby ones. Right.

Ken: Right. So before they leaf out, which is mid-March usually…

Margaret: Where you are.

Ken: Right. I’ll take nice-sized cuttings, and I just put them in water. Well, if you cut your pussy willows for decoration, don’t put them in water, because they’ll last for months. It’ll last for a year and look good. But if you want to propagate them, put them in water, and they’ll start making roots in the water. Willows do. But you want to try to transplant them into some kind of medium when those roots are less than an inch long, and still white. Because when they get a little longer than an inch, they either get tangled, or worse, they rot. So you do it young. And if you fail, or if you only get 50 percent, you’re doing O.K. I’ve never gotten 100 percent.

Margaret: Yeah. A friend came and took a bunch for her flower farm a few years ago, of my various twig willows and twig dogwoods and so forth, to eventually grow and sell the colorful stems in arrangements, because they’re so fabulous. And the thing about it is, if you want to do smaller cuttings, you have to remember which side is down, so to speak.

Ken: Definitely. Sky side up, earth side down.

Margaret: Because they won’t root the other way.

Ken: That’s right.

Margaret: It’s kind of amazing. It’s kind of wonderful to know that it “knows,” again, speaking of the intelligence of all these creatures.

Ken: It’s funny, we were talking about Eucomis, and I make Eucomis leaf cuttings. And when I cut the leaf into… I’ll take a leaf and cut it into four parts, but I take a marker and I make an arrow for the sky side. Because if I turn it over… Same with mother-in-law’s tongue, Sansevieria. They won’t root if they’re upside-down.

Margaret: Right. So that’s another one, houseplant-wise, that we could be looking at making more plants of.

Ken: Yeah. Later when the Eucomis leaves are out. You may remember I did that for a sale at Wave Hill, for a plant sale, and I think I had a dozen plants from leaf cuttings in a year. It was great.

Margaret: That’s really… And it’s not something that I would’ve thought of doing. And so I remember seeing that, but I also remember seeing your pictures of… You’d have, again with the proper side down in the moist medium, and this little creature formed on top the top.

Ken: There were clusters of bulbs [above].

Margaret: It was the weirdest thing. I mean, I don’t know what was going on beneath the soil surface, but it was like these little bulb piles, or miniature, teeny-weeny babies were being born on top of that leaf cutting. It was nutty. It was really nutty.

Ken: That’s the really exciting part of making more plants. When something like that happens. Well, when you can nurture a plant and watch it grow and you’re part of it, it’s just thrilling, I think.

Margaret: Yeah. So do you want to tell me about some of… Are you doing anything with any of your houseplants?

Ken: It’s kind of early. I looked around, and I might be dividing some of the… I guess there are Alocasia that haven’t gone dormant. And sometimes they’ll make little side shoots, and I will cut them apart and pot them up. But it’s a little early for me to make more herbaceous cuttings than things like begonias, things that are pretty easy. But in a couple of weeks I’ll be doing more.

Margaret: So you were talking about the elephant ears that we grow, almost these tropical-looking creatures that we grow. And some of them you overwinter, almost like houseplant-ish.

Ken: Right. Exactly. And the begonias are ones that have stems. They’re not like Rex begonias or rhizomatous begonias that creep. Ones like angel wing and fibrous begonias, they’re pretty easy. And I try…

Margaret: And what would you be doing, though, with those? So if I had a upright begonia… I had this one big one, honestly I had it only two years, I don’t even know what its name is. I got it at the nursery one spring a couple years ago, and it turned into this shrub. I mean, it was this massive thing, and there was no way I could fit it anywhere. And I thought, well what are you going to do? And in the fall, I cut it back. I cut out some of the stems, and I brought it in. And don’t you know, the damn thing is waking up and being happy and it’s going to be fine. It’ll probably be a shrub by the end of the year again [laughter], but that wasn’t very scientific.

Ken: I did that in the fall with some things like Coleus, I’ll cut them back and then take that new growth and root that mid-March. But with the begonia, you sort of said it, if you’ve got a begonia that’s gotten really woody and lost its leaves, I’ll make a cutting to have a new plant, a juvenile plant, because a lot of them look better as children, and then I attempt to discard the rest of it [laughter]-

Margaret: And you fail, and you don’t have the heart to get rid of it.

Ken: And often I fail. No, that’s why I cut that Taxodium outside. I thought, is this cruel, or is this horticulture? That’s what I ask myself. Because a lot of people would think it’s torture.

Margaret: So with the piece of the… Let’s say we have this begonia, and it has these upright stems. And so if we took one, and we… Would you first root it in water a little bit, almost like that willow you said, just so it gets slightly rooted, and then put it in medium? Or what would you…

Ken: Well, it sort of depends on the plant, but I think if it’s mid-March and if there’s new growth starting, I’d probably take a cutting of a tall angel wing, I’d take maybe a 3- or 4-inch cutting, and I’d put it in something like moist perlite.

Margaret: Maybe put a little plastic wrap exactly over it.

Ken: Exactly, I was just going to say…

Margaret: Make a little hood, like a little terrarium-ish.

Ken: Slip it into a plastic bag that’s open, and leave it open. Or in an old aquarium that’s open. You want to have humidity if you can have it.

Margaret: But not rotting, not soaking. O.K.

Ken: Right. When I close stuff up, I know people do it, but things rot for me, so I always like to leave a little bit of air circulation.

Margaret: I never had this before; it’s such a common houseplant, the Tradescantia, I think it’s zebrina or something, it’s purple on the underneath and striped on the top. And the poor thing, I had just gotten it as some filler in an annual pot. I didn’t have the heart—big surprise, to throw it away in the fall. But it just looked like… I mean, this is just a week ago. It just looked—I couldn’t even believe it was still alive [laughter]. Some of the pieces were hanging way down, cascading over the edge, they were attached to what looked like dried-up wire. You know what I mean?

Ken: Yeah, I do.

Margaret: And yet they were still alive. And I’m like, “What are you doing? It’s like you’re on 6 inches of dead-looking stuff, and then you’re alive down there hanging down?” So I took those live pieces, and I did a glass of water and stripped them down, and left a few leaves at the end and put them in water. And I thought, I’ll try. What the heck? I can use it as filler in a pot again. So when you said the thing about the coleus, is that… What would you have done with that? You said you had propagated them?

Ken: Things like coleus, I can’t think of a lot of things… Some things that we get in the garden center or that we’re growing and they’re decorative outside, we put them in pots, and then what do you do? So I usually bring them in and put them under lights actually. So I’ll cut them back to like 3 inches, and then this time of year, they start to push new growth.

Margaret: And so you use that as your stock plant for cuttings.

Ken: I use that. Right. Because then they’re young, new juicy growth, that’s going to root very easily.

Margaret: O.K. And you root it in water, or you put it right in that medium again, like you were just saying with the other things?

Ken: Under the lights where it’s humid, I’d do it in medium right away, but that Tradescantia, you could probably grow it in water for five years, but then it’ll be quite a mess. I like to get them into medium when the roots are not too long.

Margaret: As soon as possible. O.K.

Ken: Because they get all tangled.

Margaret: So before we run down on our time, I just want to make sure that we get to some seed things.

Ken: I’ve taken all my packets, and I’ve arranged them by the date that they should be sown. And I’ve written on the seed packets, or even some seeds that I’ve saved and put in envelopes.

And the way I do it is, I get a three and a half-inch plastic pot, and I’ll do each plant in its individual pot. I don’t do them in a flat together. So all the tomatoes will go into… One kind of tomato will go into one pot, and another kind of tomato, very soon, I guess mid-March, go into another pot.

And I’ll fill the pot first with some medium, fill it all the way to the top, and then press it down with an immaculately clean other pot [above], and fill it almost to the top. And I put the seeds around, and then I cover them with a little bit of medium, so that they’re covered with medium equal to their thickness. So it’s not much. I don’t bury them. And if the packet says that the seeds need light to germinate, then I don’t bury them at all. I’ll do them on the surface.

But on the surface I sprinkle granite grit on [below], which is what the rock gardeners do. On all the pots, I sprinkle a very thin, one- to two-grain layer of granite grit, because it’s inert, and the medium won’t dislodge it, even when you’re spraying water on it if you have to water it again. And since I’ve been doing that, which is like 20-something years now, I haven’t had the series of fungal diseases that’s called damping off, where the seedling comes up, it looks great, and then all of a sudden the next day it keels over.

Margaret: It drops dead. Yeah.

Ken: But the granite really helps. And then when they’re larger, I’ll transplant them. And the other thing that you do is you take those seedlings outside, and I’m going to try that this year if they’re not too heavy, because I think I’ve left them on the heat mat too long.

Margaret: It’s no accident, really, that the mat is technically called a germinating mat or a germination mat. It’s for germination. It’s not for growing. And so in a laboratory environment it’s only used for germinating, or in agriculture is only used for germinating. The minute you see any growth, that thing has to come off.

It doesn’t mean then that they want to be cold. The room, the ambient temperature still has to be whatever that plant needs. A tomato needs warmer than a lettuce or spinach or a broccoli. But it means that they don’t want that cooking of the soil, that bottom heat that’s going to stretch them out, like too little light would stretch them out.

Ken: That’s just what it does. It stretches them out.

Margaret: It stretches them out. Yeah. So we should just say, the granite grit, this is poultry grit, and you can frequently get it at a place like a Tractor Supply store or whatever. You can even get it online, but it’s expensive to ship. But it kind of looks like birdcage gravel. So it’s little, and there’s different sizes of it. Yeah. Granite grit.

Ken: It comes in three grades. And if you can only get one, get the starter grade, which is the smallest. It’s like very coarse sand. And granite’s good because it’s not alkaline, and you want one that doesn’t have any additives, which is available. You can find it. And not oyster shell, because that’s really calcium.

Margaret: Yeah. And sand is a possibility. Not beach sand, but clean…

Ken: Yeah. As coarse as you can find it.

Margaret: Yeah. Clean, sharp sand. That is another possibility. And I know other people who use that in propagation as their topdressing, their mulch, their thin cover of the seeds, as you describe.

Ken: Yeah. I don’t use vermiculite, some people do, but I don’t use vermiculite for anything. That’s another story [laughter].

Margaret: Yeah, I think the other thing that’s really important, besides the hygiene that you were just talking about, is good light, not a windowsill environment, but proper light. And then also… now I’ve lost my train of thought [laughter].

Ken: You were talking about light, and it’s funny because it’s changed so much. When the seeds are in the pot, I think probably the top of the pots are like 4 inches from the light. It’s a lot of light. And I used to have fluorescent bulbs and tubes, and they were hot. So that’s another problem.

Margaret: Yeah. These new LEDs don’t emit so much heat, which is great-

Ken: Hardly any heat.

Margaret: …because that can also stretch out the seedlings. But I remembered what I was going to say, which is that you were describing this community pot where you take one variety of tomato and you put it all in one pot to get started. And so then when those show their first little true leaves… So it might be 10 of them or 20 of them, seeds, it’s not like one tomato seed in that three and a half inch pot. And then when they are far enough along, they start to show their first true leaves. You prick them out, you take out those seedlings and give them each their own little cell or pot depending on what the plant is and what it needs next.

Ken: Right. And no longer on the heat mat [laughter].

Margaret: Right. So I just wanted to double back to that, because we’re not saying that you start with a million three and a half inch pots [laughter], where you wouldn’t have enough lights or heat mat ,to get anything started in this community of each variety. And then those are potted, onto a slightly larger quarter, each individual plant.

So of course we’ve used up our time, and we haven’t made that many more plants, but I’ve got to go down to the cellar now and see the Eucomis and tell them you said hello.

Ken: You do that.

Margaret: All right. And I’ll talk to you soon. I’ll see you at the Virtual Garden Club before long.

(Photos by Ken Druse except as noted; used with permission.)

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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 14th year in March 2023. 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 20, 2023 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).