MAYBE YOU CAN feel it where you garden, too: a slight shift in the weather, which combined with shortening days, means summer is loosening its grip. It’s not fall yet. It’s not cleanup time, but what time is it in the garden right now? Ken Druse and I are each under way on projects that are just perfect for this moment, for the in-between time. From sowing biennials, to collecting seed of some annuals, to eradication of enthusiastic groundcovers and more that we are doing, and want to tell you about.

Author and photographer and old friend Ken Druse—the guy who started laughing before I even finished the introduction while taping this show (and whom you can also find talking plants on Instagram)—joins us again today as he does each month. This time, he wants to tell us what he’s sowing and saving, what he’s propagating.

Read along as you listen to the September 7, 2020 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).

Plus: Enter to win his book “Making More Plants” (affiliate link) by commenting at the very bottom of the page. (Hit the little down arrow there if the comment box isn’t showing, to display the form.)

saving and sowing biennial and annual seed, with ken druse

Margaret: [Ken laughs before he is introduced.] He’s laughing already. Hi, Ken. How are you?

Ken: I’m fine. I guess I thought you were amusing. You are amusing.

Margaret: I’m amusing. I’ve lost it completely [laughter]. Before we get started, I guess, because you’ve given me a preview that you’re sowing and collecting seed madly over there, we should definitely pair this up, the transcript of this show, with another giveaway of your propagation book, “Making More Plants”-

Ken: Oh my goodness.

Margaret: … because it’s always the most popular thing. Everybody’s so excited about that book because it’s such a great manual. So: What the heck are you doing over there?

Ken: Well, this idea started because I… When we talk, I think, “What am I doing? Oh, yeah, I’m collecting seed of things that are ripening.” This is the perfect time to keep your eye out for seeds, especially of ornamental plants that you want to come back next year.

And I know you’ve got an abundance of Angelica gigas [below in bloom; a seedhead is at top of page]. So those biennials, the plants that either sow themselves right now, or we can collect the seeds and scatter them, or we can collect the seeds and start them indoors in the winter, but it’s time to catch those seeds before they drift away. And like the Angelica... I can’t grow gigas; we’ve talked about that, but I can grow archangelica, and atropurpurea. You ever seen that one with purple stems? It’s so beautiful, and pachycarpa… Sorry.

Margaret: He’s talking Latin, folks. He’s already… We haven’t even gotten five minutes in and [laughter]-

Ken: That’s their names.

Margaret: I know.

Ken: I’ll bet the Angelica atropurpurea is the purple-stemmed Angelica, but I made that name up. [Laughter.]

Margaret: Oh. Yes, and so some of those… Those angelicas are biennial, as you’ve said. What are some of the other things when you look around, that you have in the garden, that you would be targeting. Because you said you don’t do well with that, with the Angelica gigas that I grow that’s kind of got those big, wine-colored umbels of flowers at this time that followed a big beautiful purplish-green bud.

Ken: It’s weird because the other ones do quite well for me, and they’re forming their basal rosettes—kind of flat growth, which next year, just like a lettuce plant, will bolt. They’ll shoot up their flower spikes, sometimes with archangelica, it’s 7 or 8 feet tall if it’s got some moisture.

Margaret: Right, and that’s a good… What you just said when you said basal rosettes: One of the important things—and maybe, we’ll get to this later—but know how to recognize these babies. Because if they sow themselves or if you sow some of them outside, you don’t want to destroy it accidentally later [laughter]. You know what I mean? Sometimes that takes a little homework. Looking things up, and I always love when websites show, or reference books show the seedlings, the babies, as well as the grownup plant. Anyway… O.K. We’ll get to that later. [Above, verbascum, columbine and angelica self-sowns at Ken’s.]

Ken: Well, Digitalis, and I don’t have so much luck with the regular foxglove that everybody loves, for some reason. I think this is all due to my sandy soil. They want a little more moisture. But the other Digitalis like ferruginea... is that the one? And lanata, I think is one, and lutea, which is this little plant… Well, the plant’s not that little bit, but the flowers… The spike is covered with these creamy yellow, little flowers, but it’s covered with them. And that self-sows, or you can collect the seed, or you can sprinkle the seed where you’d like it to grow, and it’s not a big thug. Usually one plant will drop a seed, or lots, and then you’ll get one plant again.

I do sow Verbascum; I have a hybrid verbascum that I collected my own seed from, and I scatter those. Sometimes I’ll cut off the flower spike and lay it where I want the plants to grow next year, and they’ll sprout right away and form those rosettes for next year.

Sometimes, actually, it takes two years. They’ll sit as rosettes for two years, but you can really recognize them because they’re big, flat, hairy things, in a beautiful way [above].

Hollyhocks are kind of… sometimes they’re short-lived perennials like Aquilegia. Now, what’s the common name for Aquilegia?

Margaret: Columbine.

Ken: Yes. Of course. [Laughter.] They’re short-lived perennials. If you grow columbine, you’re lucky if you get two years out of them, but you’d sow the seeds now outside to have them bloom next year, and maybe even the year after.

Lunaria… Do you ever grow Lunaria? [Above photo from Wikimedia.]

Margaret: I haven’t. Now, is that that money plant, or something like that?

Ken: Yeah, or a silver dollar plant, as-

Margaret: Silver dollar. Right.

Ken: There’s lavender ones, they are the species, and there is a white cultivar, and there’s a variegated one, too. But the white and the lavender ones are good plants and not too aggressive for me. I usually get one plant after where there used to be one plant, and they grow about 2-1/2 feet tall, bloom the second year, and they’re fragrant. They’re members of that big Brassica family, so like a plant that we try not to grow, the Hesperis, it has that really nice kind of powdery, clove-y smell. It’s very-

Margaret: The Hesperis is the dame’s rocket, which is an invasive alien plant, a plant from elsewhere that’s sort of taken over a lot of our woodland edges and roadsides and so forth, so we don’t grow it. Whereas in… if you were to read… and you’re making me think of Sarah Raven, the English gardener, a well-known English gardener. If we were to read her list, I bet, of biennials on her website or something that she’s written, we would see Hesperis on the list of doing what you’re just saying, and we’d also… She’s crazy about the Lunaria, the money plant. She loves both the purple and the white.

So there are some places where one of these biennial self-sowers, or annual self-sowers, is too enthusiastic or not appropriate, and other places where it is. If people are listening, even across the country from us—we’re in the Northeast—but in California, some things may not be good on the list for there, right?

Ken: Yeah, like fennel that grows on the side of the road everywhere there. But Hesperis, I believe, is European, so for Sarah Raven, it’s a native plant.

Margaret: Correct, and that’s what I’m saying, is that the list has to be tweaked according to appropriate to the garden of course, aesthetically and all that, it’s important, but also, environmentally speaking. And so it’s going to differ from place to place. You didn’t say Dianthus. Now, do you ever… Have you ever grown Dianthus? Any of the little pinks or whatever? Do they self-sow?

Ken: Not for me.

Margaret: I was curious because I-

Ken: Sometimes they don’t even bloom.

Margaret: [Laughter.]

Ken: I guess… I mean, I have silver foliage that hangs on for a couple of years, and I don’t know.

Margaret: I’ve always wondered about those like, “What comes next?” But maybe I’m wrong.

Ken: Well, there are annual, ones and there are perennial ones, and there are the Alpine ones, so maybe you’re… And there are carnations, also, so maybe you’re growing a hardy annual.

Margaret: Yeah. Maybe it’s the annual kinds that do, too. And you said larkspur. Did you say larkspur?

Ken: Well, Larkspur is a hardy annual and opium poppy is a hardy annual, so they’re not exactly… Like I said, short-lived perennials, those aren’t exactly biennials, and opium poppy, also… I usually sow opium poppy on the snow in winter, but that’s just fun, and it loves it. It wants that cold. [Above, opium poppy seedpods upside-down in a bag at Margaret’s.]

Margaret: You said… I jumped ahead, I’m sorry, to sort of collecting seeds of annuals that like to self-sow. But you said a little bit ago, “sowing seeds now outside,” and… Do you take your cue from the plants? Do you see them setting seed and you say, “Hey, this is a good time.” What’s your-

Ken: Well, that’s how this whole thing started for me. I’ve got a really nice Nicotiana that’s very fragrant, and it’s tall, and every flower turns into a fruit. People think that fruits are juicy, but there’s sort of two kinds of fruits. There’s moist fruits like a raspberry, but there’s dry fruits. Anything that has seeds inside of it, is a fruit. And the nicotiana’s… I don’t know what you call them—fruits, dry fruits—are like little open urns. They’re a little bigger than a quarter of an inch, and if you tip them over, scores of seeds will pour out, so I try not to tip them over until I hold-

Margaret: It’s quite amazing. Yeah.

Ken: … a cup under them [above, at Ken’s]. I take a cup out to the garden and I just turn them on their sides and the seeds pour out, and then I save their seeds in, usually, a little white envelope. I guess they sell them for stamp-collecting or something. And I seal the envelope and I put that envelope dry in a jar, which I store in the refrigerator until I need them.

But I also let some of those seeds drop where they are, and it’s not an annual, actually. It’s a tender perennial, but it acts like an annual. It blooms the first year, and some of those seeds will fall to the ground, and maybe one or two, for me, will grow. For you, they all grow. [Laughter.]

Margaret: Maybe 1 or 2,000, for me, will grow, and that’s really because of where I had my first ones sow and colonize was in the cracks and crevices, for better or worse, in a patio sort of an area. And they love that spot, so they really do well there and I get maybe too many of them.

This kind of brings up… O.K., so that’s a little bit about timing: how you were inspired, like with Nicotiana, with the flowering tobacco, you were inspired to a moment ahead of it dispersing the seed itself. You tipped it into a bag or a jar. Yeah.

Ken: They’ll just pour out in the breeze if you don’t get them.

Margaret: Right, so you took the cue from there, and you’ve mentioned a couple of times about like… I think with the Verbascum… And maybe the last time we spoke, we were talking about taking cuttings. Another form of informal, but doable, sort of DIY propagation that anyone can try. We talked about taking cuttings from coleus and so forth on the last show. So I guess what I wanted to know is besides anticipating the timing, do you prepare the space to lay down that verbascum seedhead or…?

Because what I found is that… I made a bad mistake this year because we were all so crazy this year. I mean, look, we’re under so much stress collectively. And so I wasn’t having my events, my public events, and so I just sort of was like, “O.K. Let’s clean up and mulch the whole garden and then forget about it.” [Laughter.]

It wasn’t timed to be ready for something in particular, so I shifted the timing of when I did things. And I sort of shot myself in the foot because I mulched two areas where I had Verbena bonariensis, the tall verbena with purple flowerheads [above]. I mulched them too early. Looked great; all cleaned up. “Hey, I’m ahead of the game.” I was so proud of myself, patting myself on the back, and guess what I don’t have any of now, and the butterflies don’t have any of now?

Yes, because that palette, that bed—I zonked them. [Laughter.] I mean, I deprived them of light and who knows what else that they might’ve liked, and they couldn’t come up through the inch or 2 of mulch. So what do you do… besides timing, what else is your sort of preparatory thinking?

Ken: Well, your nicotiana is a good example. First of all, if they’re coming up where they’re coming up, they like where they’re coming up. So one place you might sow some seed or encourage seeds to fall are where the parent is, because they like that, and you’ve got that gravelly area that the nicotiana was crazy for. So if I’m looking for a situation to have more of those plants, I’ll try to make it like the parent—I’ll look for something like the parent.

And with a biennial that’s kind of wildish, I don’t think I would put it in the rows of the garden bed or something like a vegetable bed, I’d want it to look a little accidental, so I just look for a place that’s pretty much like the place that the parent’s growing in. Does that make sense?

Margaret: It does. Remember that… This seems obvious, but it’s not. We get to raking, two months later, and leaves have fallen on top of the place, and we get to raking and guess what happens? Again, we do ourselves in. We undo what we did. We have to… I think we have to mark off these “nurseries,” so to speak; these moments. Because otherwise we can rake them right up or like I did, I forgot, and I didn’t let the verbenas sprout before I mulched, and that was a mistake.

Ken: That makes me think of something, too. Biennials don’t like to be moved.

Margaret: No.

Ken: If I have some nice basal rosettes that are in the middle of the path of a verbascum, sometimes I move them, but they end up… If they live, they end up being kind of small. They want to be where they want to be and where they start, so that’s something to think about, too. I don’t know if we have time to talk a little bit about collecting seed.

Margaret: I think we should. I think we should just keep on keeping on.

Ken: [Laughter.]

Margaret: Definitely. You said they don’t like to be moved, and I think, because I move around—speaking just one last thing on the biennials—I move around, at this time of year, so late summer-early fall once the rains start again somewhat, so that the soil is moist and they’re hydrated, I do move around that Angelica–

Ken: I knew you were going to say that.

Margaret: … and paint pictures with it, so to speak because this is the thing about these biennials and self-sowing annuals: They want to give you more free plants. They want to produce. They’re happy. If they’re in a good space and you don’t screw it up by either raking up the area, either in fall cleanup or the next spring cleanup, either, or dousing it with mulch like I did, they want to cooperate.

However, they’re not the best designer sometimes. They will be spontaneous-

Ken: They come up in the wrong place.

Margaret: Yeah, or you get 500 of them in one spot and you really wish-

Ken: No. You do. [Laughter.]

Margaret: … and you wish you had… Right. You wish you had some across the path also to flank the path, or you wish you had some in another bed to repeat the theme of that moment in your garden more widely and so forth. So this is a good time, as is early spring, to move… I can move some if they’re really not too far advanced and if it’s moist, consistently moist. Anyway-

Ken: Do you try to take a lot of… You try not to disturb the roots obviously.

Margaret: I try to take a wedge of soil, so to speak.

Ken: Exactly.

Margaret: Yes, yes.

Ken: You wouldn’t prick it out like a seedling.

Margaret: I would not, not bare-root it if I don’t have to, and I would… So I would probably use my hori-hori, my Japanese weeding knife, and kind of put a little wedge of soil. Yeah. Anyway, I didn’t mean to stop you from going on to collecting seeds, but just that was a thought. [Above, Angelica seedlings at Margaret’s moved with a sharp, narrow trowel, with rootballs of soil.]

Ken: Well, I get this thing all the time that people don’t realize that dry fruits are fruits. That peas are in a pod and that pod will ultimately turn brown and be dry, and that’ll be a fruit. And it’s where your seeds are, and you can take those peas and dry them, and then you can sow them.

But there’s so many fruits that are… I mean, there’s as many fruits that are dry as there are moist fruits like a raspberry, and a lot of those dry fruits explode. [Laughter.] They’ll split along that seam, so if I’ve got something like a daylily that I want to collect the seed from, and it’s ripening, I’ll put a paper bag over the stalk of the seedhead and tie it so when it explodes, or splits open, I don’t lose the seeds, which are pretty big.

Or I’ll cut that stalk and put it in a paper bag upside-down, and tie a rubber band around the bottom or something, and hang it someplace where there’s a lot of air circulation. And I label the bag with the name of the plant and the date because you always forget, even though you think you never will forget.

But those moist fruits… If I have a raspberry I want to sow the seeds from, which I don’t generally but it’s a good example, I’ll smush it against the paper towel and try to get those seeds free. And then I’ll wash them in a fine sieve, because in the case of moist fruits like Jack-in-the-pulpit with berries and things like that, it’s often the moist flesh that keeps the seeds from sprouting in the wrong place at the wrong time.

In all these cases, I want to clean the fruits. I don’t want any chaff like you might have with wheat or rice or something like that. I grow an ornamental annual red rice that’s just so gorgeous, but I clean all that stuff off, because that usually has either insects or disease pathogens. And then I slip the dry seeds into an envelope in almost every case, not every case, and stick that [in a jar, above] in the refrigerator.

When I said, “Not every case,” there are some seeds that want to germinate right away like our biennials, but there are even perennials. Now, we talked about hellebores just doing too well on their own. [Laughter.] If only we knew that 30 years ago, when we were paying so much for them.

Margaret: By that you mean the plant, once it gets established, will frequently… If you sort of pick up the leaves and look, you’ll see a ring of tiny seedlings where the flowers have dropped their seed the previous summer. Yeah.

Ken: Well, actually, two summers before, probably. [Above, hellebore seedlings near one plant at Margaret’s.]

Margaret: Ah, right. They take a while to germinate. Yeah, and that’s another thing, by the way, that I moved. I started with one area and then I repeated that, so sort of free hellebores, and this is a time of year when I do move them. I frequently wait until they’re bigger, a little bit bigger, like the second year after they appear, but you can move them really tiny as well, anyway… Seeds.

Ken: And you can mow them.

Margaret: [Laughter.] Right. When they jump into the lawn. Right. Right. Right.

Ken: When they jump into the lawn, and when I first encountered that, I thought, “Oh no. No….” And I was… I usually give them away. I shouldn’t do it, but, “There’s the mower, there’s the babies in the lawn path. What am I going to do? Oh no.”

Margaret: Yeah. You would anticipate before the thing is going to split this pod, this fruit, this dry fruit is going to disperse. I mean, with the poppies, if you don’t get it and then you have a windy day and that pod… You know what I mean. They’re just going to fly all over the place. They’re so tiny. You can’t find them on the ground.

In the vegetable garden, if a bean or a pea pod splits, like with ‘Scarlet Runner’ beans it happens all the time, and late in the season and I find the seed on the ground. Well, it’s pretty easy to find, it’s the size of my thumbnail, but I’m not going to find nicotiana seeds; I’m not going to find poppy seeds. What else are you collecting? What are you looking for besides… seed-wise?

Ken: Well, nicotiana, daylilies, hosta, which are perennial. My primroses, I cut the stalks when they’re just turning brown. Otherwise, they get moldy; it’s funny. And then I stick those in a paper bag like I described. Nasturtiums, alliums—you can collect the seed of alliums. Cleome, Rudbeckia—black-eyed Susan. Cosmos, Impatiens, they’re annuals, but you can collect the seeds of those. Morning glories set seed in their fruits, and the moon vine. Moon vine have gigantic, really cool fruits, actually. Four o’clocks. The columbines I mentioned. You mentioned larkspur. Feverfew—Tanacetum. Wow, that’s a big list. I gotta get busy.

Margaret: Something like Calendula, if you don’t want it to sow itself all over your vegetable garden, but you do want to have it, either for edible flowers next year or just for enjoyment, collect the seedheads now or when they formed. Because otherwise, it’s just going to be all over the damn place, and you’re going to end up weeding them out probably.

In the last couple of minutes, I wanted to ask you, you just said primulas. O.K. You collect the seeds, but then what? When is that… Because that’s when I’d like to do better with. When do you then sow them in? Do you sow them indoors, or what do you do? [Ken’s improvised primula propagation setup, above.]

Ken: I’ve done a lot of different things, and the most success I ever had was to put the seeds on the surface of the medium… in a big, flat, like a nursery flat that you put pots in and take home. And then I cover that with a kind of… Actually, this is what I actually did: I covered it with the kind of nursery flat that has sort of a pattern on the bottom for drainage that’s really open, or you could do it with some kind of wire or something, just so that animals don’t go to this 2-1/2- inch deep thing, and then I put it outside. A place where it got snow on it and rain on it, and then in the spring, they sprouted. And I’ve tried a lot of different ways. I also do them in pots on gravel, but they want a cool time, a cool period, so I just do it outside and then I move the seedlings.

Margaret: O.K. All right. In the introduction, of course, I mentioned I didn’t know how many things you were sowing and collecting [laughter], but I mentioned that I’ve been on this binge for this perfect time in the garden, again, when it starts to be a little moist and it’s cooler. I’ve been trying to eradicate some of my most ambitious and oldest areas of groundcover—Lamiastrum, and also Vinca from the previous owner, not even me, etc. And I’d love to propose that we talk about that next, so that we both sort of put our thinking caps on and prepare to talk about sort of living mulch, pros and cons, and what is a good groundcover? You know what I mean? I think that’s an important question. I think we need to rethink it because a lot of other-

Ken: Yeah. I’d add Pachysandra to your list.

Margaret: Yeah. All right, so is that good? Can we do that next time?

Ken: That’s good, and then some time after that we might talk about getting the plants in for the winter.

Margaret: O.K. Maybe we’ll do both. All right, so I’ll talk to you soon. Thank you.

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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its 11th year in March 2020. 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 September 7, 2020 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).