repotting houseplants (plus blooming favorites), propagating coleus & more: ken druse q&a
WHAT REALLY PERPLEXED or downright frustrated gardeners in 2018? I asked that recently on Facebook and elsewhere, harvesting the final crop of Urgent Garden Questions for the year, and Ken Druse helped answer them as we do each month on the radio show and podcast.
My longtime friend and fellow garden writer Ken of Ken Druse dot com is author of many books including “The New Shade Garden,” and “Making More Plants,” and “Natural Companions.” We tackled subjects ranging from propagating coleus from cuttings, to repotting a jade plant—and repotting in general—and even why a jade might be blooming now, after many years of ownership with no blooms. Ken shared ideas about some of his favorite unusual houseplants, too (that’s one of his Thai hybrid euphorbias, above), including several that bloom in the offseason.
Read along as you listen to the Dec. 17, 2018 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).
year-end q&a with ken druse
Q. Hi Ken. How are you, Froggy?
A. Ribbit. Ribbit.
Q. I knew it, I knew it would be. I’m Froggy, too, I’m sorry.
A. Well, I had a cold, then I had bronchitis, and now I’m having another cold.
Q. Oh, I think I just am … just falling apart, but whatever, anyway. Every time I’m around small children. I blame small children.
A. I’ll say.
Q. They have large germs. Yes.
Q. But they are adorable.
A. You should make a T-shirt, or embroider a pillow, or something.
Q. So, I know my overall Urgent Garden Question of 2018 is, “What’s up with the weather,” but we won’t go there, right?
A. It’s typical.
Q. No surprise, probably since it’s been cold in a lot of areas of the country already, we had a bunch of sort of indoor-ish questions since it’s that time of year. One from this person named Joan, who said her question is about coleus. She bought some coleus seeds, the variety is ‘Chocolate Covered Cherry.’ And they were easy to grow and grew well, and really pretty, she loved them, she said, “Hey, I’m going to take some cuttings,” and she put them in a potting medium, has kept them moist, and they’re doing great.
The only thing, she says, because she wanted to carry it over for next year, “is that the new growth is totally different from the original color. I thought I was cloning them with this cuttings method. Can you explain this different growth to me?” Got any thoughts about that? [Photo above of ‘Chocolate Covered Cherry’ from Pan Am Seed.]
A. Well, see, she was cloning them.
A. She did make clones.
Q. Which is asexual reproduction, right, that’s what we mean by that?
A. Yes, or vegetative-
A. ... we sometimes say.
Q. Right. Right.
A. Non-sexual, right? Not from seeds. So, she’s taken the actual genetic material, and produced some new plants. But if she’s done it in the fall, and she’s doing it in even a sunny window or maybe under lights, that’s probably what’s going on, is she doesn’t have as much sun. And to get those colors, especially those dark colors, it’s almost like … I shouldn’t say sunburn, because it doesn’t really harm them, but they really need that intense summer sunlight to bring out that color.
Q. And even the ones that, you know, we think of coleus as a quote shade plant even though in recent years they’ve brought out the “sun coleus” varieties and all that. It’s still, even outside in the semi-shade, it’s bright compared to anywhere in the darkest days of the year, which we’re in right now.
A. Not to mention glass.
Q. Right. Exactly. So, yes. And even if she’s got them under plant lights and so forth, it’s still not quite the same, I don’t think. I agree with you, I think it’s … Because I’ve got other plants that I’m carrying over in the house, not coleus specifically, but everybody looks a little peaked, do you know what I mean?
Q. I mean, it’s not quite the same. Yes. So, I think that’s a light thing. I agree with you, and that they really fade in indoor low light, especially.
A. So, hang on, Joan.
Q. Hang on, hang on. And if the plantlets look healthy, I think that’s great. Some people I think have to take cuttings again, right? Because they get kind of-
Q. They get kind of stretched out.
A. Cuttings of the cuttings.
Q. To have a good sort of stout, stocky thing, when the time comes for next May or whatever.
repotting a jade plant, and when jade blooms
Q. So, Kathy wrote in to ask how to re-pot a jade plant. And I thought it was interesting, because at the same time, almost the same day, a friend of mine, Katrina, wrote and said, “My jade plant that I’ve had for a million years is blooming. What in the heck is going on?” So, jade plants, should we start with how to re-pot? [Katrina’s photo from Instagram, above.]
A. Sure. I don’t know how big this plant is, but it’s not easy, especially when they’re really old. Jade plants are very brittle, and when you try to re-pot them the pieces break off, then you make cuttings and you have too many plants, but that’s another story.
So, what I would do is wrap newspaper around the plant, and sort of cinch it in a little bit, make a collar or I could even say a girdle, not too tight, of newspaper, and tape it. So, when you’re moving it around, it’s pretty much protected. And then you either turn the pot over, if it’s not too heavy, and knock it on a counter edge or something and it’ll slip out. If it’s a very heavy plant, you can turn it on its side to try to get it out, rapping the pot with your fist as you turn it. Depends on what kind of pot it is.
Q. And that’s wrapping with an R, not W-R-A-P-P, it’s rapping with an R. [Laughter.]
A. Oh, no. Yes. Or you could take a knife or you know what would be good, like a palette knife, or an icing spreader, something flexible.
Q. Right. Right.
A. And go around the inside rim of the pot. If it’s a plastic pot that’ll be easy because you can squish it. And then slip it out and pot it up. And I’d say only pot it up one size, but that’s kind of a general thing that I do. So, if it’s in an 8-inch pot, you go to a 10-inch pot, etc.
Q. Right. Now, I didn’t know that in its native South Africa, I think it’s from the Cape Town region of South Africa, originally, the jade plant, and didn’t know that it actually is a small tree. Like a shrubby, it’s like a shrubby like-
A. A shrub, right.
Q. Maybe 6 to 10 feet or something. But crazy, right? I mean, and here we are we’ve been sort of pinching off bits and making them into houseplants, and sort of keeping them small by keeping the root system constrained in pots, right?
Q. Yes. Fun. So, really, the key to successfully re-potting one, you’re , is that first we need to protect the above-ground growth so that it doesn’t get all banged up in the process by making this sort of collar?
A. That’s what I’d do.
Q. Yes. O.K. And do you do that for other plants? Are there other plants that are sort of tricky?
A. Well, I do that with cacti, just to protect me.
Q. [Laughter.] Self-defense.
A. Not to protect them.
Q. So, all right, so that’s … It kind of brings up, and like I said my friend Katrina at the same time was saying, “Mine’s blooming, mine’s blooming.” Do you have any idea like why that is? Or have you ever had one that bloomed?
A. Well, it’s funny that you’re saying that because I did actually speak to someone recently about that very thing, because I’d seen them blooming in California, in San Francisco, actually, where they’re shrubs, and then people grow them sort of you know in the hellstrip right along the road, or the street. And they have kind of nice, starry white flowers. And they get covered with them. So why?
Well, outdoors in San Francisco, I can guess they’ve gone through the winter. So, indoors with the plant, it’s probably cool temperatures, maybe the plant was kept dry, which if you want it to bloom, that’s what you would do. But I think, also daylight length. I was going to say daylength, but all days are 24 hours, Ken. It’s the number of daylight hours.
Q. [Laughter.] Right. And actually, is it long nights that helps … Because I mean, I’m thinking now, I said before Cape Town region of South Africa, so I’m thinking you have a sort of dry, cooler … during your short day period, during your rest period. I have other plants that are from the areas like that in the world, Clivia, where what triggers it is cool, dry, the shorter days, and it rests then, and then boom, it’s happy—it triggers it to do its thing in the late winter/early spring.
A. Right. And one more thing is that it has to be mature, I think. If you have a cutting that you just took, and a young plant, especially of a jade plant, it’s not going to do it. And Clivia, too, wants to … It’ll only do it when it’s a grownup.
repotting other houseplants
Q. [Laughter.] Interesting. Do you, in terms of re-potting in general, do you do it at a particular time? Not with jade, specifically, but are you a person who has like a protocol? Like do you re-pot your things in spring, or fall, or any time they need it, or what’s your thing?
A. Well, if I’m bringing a plant inside from a summering outdoors and it really needs it, or if I’ve broken the pot, or something like that, I’ll re-pot it. But in general, I pot stuff in the spring when plants are going into active growth, because then there’s no chance of me overwatering them, because they’re growing and they’re using the moisture.
Q. Right. Good point.
A. In the winter, you can accidentally overwater things. You want plants to rest. And when you pot them up, they want to grow. And it’s not really the right time of year for them to grow, because as we said, they don’t have as much light, and so they’re going to get leggy, and maybe even buggy. So I like to keep my plants unconscious if possible, through the winter [laughter] so there’s less trouble for me and I don’t have to water as often. And I keep them as cool as I can do it. But you and both have kind of cool houses.
Q. Yes. O.K. So, I used to always, when my houseplants were on their way outside, in the spring, I would bring this big garden cart, which was kind of like a big plastic bucket, like the body of the cart. It’s fiberglass or something. And I’d mix my potting medium in there, and one by one I’d like bring them out, I’d put them in, take them out of their pots, get the slightly bigger pot, fill that with the medium—I used it as my potting bench, so to speak, while they were on. And I was so good about it for such a long time, and I’ve become so bad. But that’s the thing to do, I think, what you’re saying. Is when they’re on their way back out-
Q. … Do it then, yes?
A. Yes. Good idea.
Q. Yes. When they’re ready to start, yes.
A. I can’t wait. [Laughter.]
Q. Yes. You’re coming by to help, aren’t you? Didn’t you say?
A. In April. Or no, May.
Q. We have it on the calendar. O.K. good. O.K.. And you’re bringing the sandwiches. Good. Thank you.
Q. O.K. So, a lot of the questions that came, when I said “what were your most perplexing things?” a lot of them were ones that we’ve heard before, because they are the most perplexing. So, I thought we could kind of remind people that some of them we have talked about before and I’ll give the links in the transcript, if they really want to dig in deeper, so that we don’t go into too much detail about them.
But, for instance, we had another question, this time from Kimberly, about Equisetum, about the horsetail rush, and I know, I remember you have fought it yourself. She has it in her beds. [Above, a woodland in Quebec carpeted in E. hyemale; image from Wikipedia.]
Q. And you keep digging, don’t you?
A. I just pull it out, it’s not so hard to get out. And I don’t attempt to get it all out because I probably never will, but … Mostly when it’s coming up in the spring it pushes new growth and then it sort of sits around. So, it’s not so terrible. I shouldn’t say that because probably for some people it is terrible. And mine’s in a place where I can get to it. Although, it is near moisture.
A. But I’d just say, weed it out, weed it out, weed it out.
Q. Yes. So, and we did have some good links in the last time we talked about it earlier this year, so what I’ll do is, like I said, I’ll give Kimberly the link to dig deeper. [More on fighting horsetail rush.]
asian jumping worms
Q. Similarly, we had kind of a repeat question about everybody’s favorite terror, the Asian jumping worms that have become invasive in various areas. More and more both in natural areas and in gardens.
And Karen is asking should she continue to amend her soil when she’s got them and so forth. And again, with that one, I had a great interview this year with a researcher at University of Wisconsin-Madison, and kind of got the update on where the thinking is, so I want to just, again, in the name of time, to get to some new things, say Karen, we’ve got more in that interview.
battling squash bugs
Q. So, let’s see, squash bugs. Carol wanted to know about how to defeat her squash bugs, which she says are her nemesis. Do you get them? Do you grow squash or Cucurbits in your garden?
A. I have from time to time. But you mean like the worms in the stems, or?
Q. No, that’s squash vine borer.
Q. No, it’s squash bug. It’s kind of a shield shaped, brown, hard-shelled insect.
A. No, no.
Q. Anasa tristis is, I think, its … I was going to say botanical name … it’s its species name or whatever. I have lots of stories about it. I actually interviewed, a couple of years ago, Diane Alston, an entomologist at Utah State, who has a specialty in coming up with solutions for cucurbit pests.
And she said on the home gardener’s scale, the No. 1 thing we need to do to reduce this problem in our gardens, is to reduce overwintering success. [Read our interview about Cucurbit pests, including squash bugs.]
Because these bugs actually overwinter in the adult stage, they kind of like go to sleep, and if there is a food source, if there is a friendly, dilapidated old plant, anything that they know is like a friendly place to do that, they’re just going to have more success. So, what we want to do is we really want to get all that debris out of there, and if we’re not composting hot, really hot, our compost heaps, we want to actually throw it away. Like get it to another location, not put it our heap.
So, we want to make the overwintering possibilities minimized, and lots of other tactics. But that’s the No. 1, and one that could still be done even at this late date in the garden if there’s debris around to get it out of there, and you’ll minimize. So, I’ll give some links for Carol as well, in that.
Oh, and growing resistant varieties I should say, as well, helps: ‘Royal Acorn,’ ‘Butternut,’ ‘Green-Striped Cushaw’ if you’re in the South, or ‘Pink Banana,’ one of my favorite squashes, they’re more resistant than others. So, lots of info with the transcript.
crown of thorns and ken’s other indoor favorites
A. You’re talking about some interesting people that you’ve interviewed, and you probably have never interviewed Marc Hachadourian, the Director of Glass Houses at … well, Glass House Horticulture at The New York Botanical Garden?
A. He’s great. And that’s who told me about the jade plant flowering. So, we’ll just put him on the list.
Q. Oh, good. O.K. We should definitely have him on the show. Good idea.
So, going back sort of indoors for a minute, or as many minutes as we want. What else is going on there at your place? Because we’re in the indoor garden, right? If we’ve got anything going on, it’s the indoor garden. What’s going on?
A. There’s lots going on. I’m kind of surprised. Have you ever seen the Camellia sasanqua called ‘Yuletide’ [above, photo from Ken’s]?
A. It has the most perfect name, because the flowers are so red, and the leaves are so green, it’s the ultimate Christmas plant, I think. And it’s one of the easiest camellias to grow. It just wants a cool temperature, summering outdoors. It’s funny, we were talking about re-potting, I potted that plant down. It was never growing and it never looked good, and I un-potted it, just wondering what’s going on, turns out it hardly had any roots. It was over-potted. I don’t think that’s ever happened to me before. So, I put it in a smaller pot, and it doubled in size.
Q. Interesting. Huh.
A. Weird, huh?
Q. So, it liked the confinement. Interesting.
A. Yes. Well, it’s not confined yet, but it … I guess it probably was too much moisture and stuff like that.
Q. Right. It was just swimming.
A. I’ve got some abutilons, flowering maples blooming.
Q. I love them, yes.
A. I was given a very special abutilon that was supposed to be a double pink powder-puff abutilon, and it turns out to have these gigantic flowers for abutilon, they’re like hibiscus orange flowers, I’m not sure what it is. There’s one that’s like it that has bells, but this is not bells, these are flat and open [above, at Ken’s].
Q. Interesting. Like disks? Like big ‘Disco Belle’ [hibiscus] kind of things? Yes. Huh. Interesting.
A. Yes. It blooms all the time, in the summer, too, but mostly right through the winter. But I have to tell you, the thing that turns me on the most, and it’s very weird, are the euphorbias, the Euphorbia milii, the Thai hybrids. Are you familiar with those?
Q. No. Do they have another common name?
A. They’re crown-of-thorns.
Q. Oh, O.K., crown-of-thorns euphorbias.
A. A lot of people like that like the jade plant because it’s so easy to grow, it just wants a sunny window and the bad thing is overwatering. So, you just leave it alone, especially in the winter. But I was in Florida, probably about 12, 15 years ago, and I saw a crown-of-thorns with flowers that were almost 2 inches across. And I did some research, and turns out these are Thai hybrids. They’re actually from Thailand, and I got some when I was in Florida, and then I’ve gotten a few more as rooted cuttings. Some of them came from Thailand, now you can find them on Ebay, believe it or not.
A. And they have incredible spotted and splashed color flowers that are green, and red, and pink, and white, and cream, and they’re blooming right now in the winter, a little bit, but in the summer they’re just … It almost looks like they are hot-house geraniums, when the red one’s blooming. It’s this big ball of flowers. They’re great.
Q. Huh. So, you found your first one in Florida and you’ve had them for how long?
A. About almost 15 years. They grow straight up like a single stick, which is not very nice, and then the pot falls over, so I tried to-
Q. Oh, you’re making me want millions of them. Oh, that sounds great. I’m teasing.
A. I tried to get it to branch by cutting off the top. And of course I wanted to root it, and I tried that a couple times, and each time the cuttings rotted. And I talked to … I knew with cuttings of succulents, you let them dry and stuff to callus over, but I talked to someone who has a greenhouse business in Pennsylvania, and he said he does it all the time, no problem. And then I was thinking, “What’s the difference?” And I realized warm, humid.
A. He’s got a warm, humid greenhouse. So, I started taking cuttings in July, when it’s warm and humid, and I put them in the shade, and I let them callus over for almost two weeks.
A. And they’ve got leaves, and then I pop them up, and it’s been a complete success.
Q. I know, it’s so interesting that you … Because warm, humid, if you want to say callus, it sounds like counter-intuitive—humid–right? But an organic potato-farming expert told me years ago and reminded me not so long ago, if you get seed potatoes, the little potatoes to use start your potatoes in the spring, sometimes if there’s a big one in the bag, you want to cut it up and make it into multiple starts as opposed to putting a giant one in the ground. And so, you need to callus it. And he said, “Now, Margaret, don’t forget, it’s warm, humid, it’s not a warm, dry spot.” Because I think a lot of people think, “Oh, turn on a fan, dry that thing out,” and that’s not what you want to do. So, again, this is another one of these sort of propagation-y kind of things, like you’re talking about with yours, where we’re multiplying something, but we need it to callus, but that doesn’t mean dry it up literally.
A. Yes, I guess, because it’s … It’s not out in the rain-
Q. No, no, no, no, no, but not like baking dry, either. Yes.
A. Right. If I left it in a dry place for two weeks, that would be it. [Laughter.]
Q. Right. Right. Exactly.
A. It would shrivel up.
Q. Exactly. So, this just allows it to happen more slowly and naturally. Yes. Interesting. So, O.K., so you have … How did I never know about these things that you have these? I didn’t know about these crown-of-thrones.
A. You’ll have to look up some pictures.
A. Online. The regular crown-of-thorns have little, tiny, fire engine-red flowers, and they’re O.K. But these are just magnificent.
Q. Huh. All right. Good.
A. And so easy.
Q. So, he’s got a camellia, he’s got his abutilon, he’s got his crown-of-thorns, lots of stuff going on over there at Ken Druse’s place.
A. And I’ve got some buds of citrus coming. And that means in January and February I’ll get my paint brush out and I’ll pollinate them and a short nine months later, I’ll have a Meyer lemon. [Laughter.]
recap: black walnuts, rose rosette, beneficial nematodes
Q. So, just before we run out of time, there were a couple of other miscellaneous questions. Also, a couple more that were things that we’d covered during the year, but people continue to be vexed by them. There was one about black walnut toxicity, and are there plants that grow well under black walnut trees? There’s a great list on the Morton Arboretum website.
Someone was asking about when’s the best time to disperse beneficial nematodes to get rid of Japanese beetles, and with something like that it always depends on what product you’re using and you really need to follow the supplier’s instructions. Normally it’s spring and then again sometimes late summer or early fall. But following the directions, I think, is going to be key.
And then, of course, we had one about when is someone going to breed a rose that’s resistant to rose rosette disease. And I had great interview with an expert about that from Star Roses, and there’s a whole website Rose Rosette dot org. I don’t see anybody promising anything tomorrow, unfortunately, on that note. So, yes, lots, lots, lots, lots, so we’re going to keep doing Q and A’s in the new year, Ken?
A. Yes. This is great. [Laughter.] I’m learning so much. I can’t wait to get to your site.
Q. Crown-or-thorns, I’m looking it up when I get home and seeing what I think, if I have room for them. Yes. So, Ken Druse, thank you so much, and I hope you feel better. I hope we both stop being so froggy.
A. Yes, I’m going to go to bed right after this, I think.
Q. All right. Thank you. Thank you. Thank you, for being brave and getting out from under the covers to talk.
A. My pleasure.
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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its ninth year in March 2018. 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 Dec. 17, 2018 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).