YOU ASK, WE ANSWER: From recommendations for unusual-shaped almost bonsai-like trees for the garden (like the weeping katsura, above), to the subject of male conifer cones (yes, there are males and females!). Worried about invasive sweet autumn clematis, or seeking perfect paint colors for outdoor garden features, or the tricks to how to harvest, cure and stash garlic, and even prevent algae in water gardens?

Those were among readers’ and listeners’ Urgent Garden Questions this summer. Ken Druse, longtime friend and author of such beloved garden books as “The New Shade Garden” and “Making More Plants” and “Natural Companions,” helped me answer them.

When Ken Druse and I taped the July 2018 Urgent Garden Question show in earlier July, my most urgent question was: Will it ever rain again? Be careful what you wish for, because it started shortly after and hasn’t really stopped, with something close to 4 inches falling in about two weeks.

Read along as you listen to the July 30, 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).

the july q&a with ken druse

‘magical’ bonsai-like garden trees and shrubs

Q. Will it ever rain again?

A. Margaret, you ask me that every year.

Q. I’m sorry, I know. It gets me exhausted dragging hoses around. So yes, we have so many good questions. One that is really right up your alley because you’re kind of … I don’t like the word connoisseur, but you love good and distinctive trees and shrubs. So this is one that I want to pitch to you from Kelly, who has a new home. On three sides she’s surrounded by woodlands. She wants to find the right kind of tree or large shrub to create sort of a cozy look, but she calls it “magical,” in one open spot.

And she was inspired by pictures of my big old, like 30-year-old, dwarf white pines, which look like giant bonsais [above, one of them]. I mean, there’s no way to have that unless you wait 30 years.

But she wanted maybe corkscrew kind of trunks or things you could eventually walk under that would make a little world underneath. So that’s what she’s thinking of, like “umbrella-like,” she uses that phrase, “making a canopy” that you could maybe go under.

And, by the way, she’s in Charlottesville, Virginia, “Zone 7, clay acid, medium to dry soil,” and she’s got some sunny areas and some part shade.

A. So giant bonsai, that’s like jumbo shrimp, right?

Q. [Laughter.] That’s right, exactly. It’s the green version of jumbo shrimp. That’s correct.

A. Well, you said that she had woodlands on three sides, so I’m wondering if maybe this should be an understory shrub, tree, because your pine I’m sure is in full sun.

Q. They are, they are; they have been.

A. Because the conifers really want a lot of sun. But I’ve got a spot here and I have grown … I planted it a long time ago, a weeping katsura. That is Cercidiphyllum japonicum ‘Morioka Weeping’ [photo top of page], which came in the mail. It was like 18 inches tall and now it’s 25, 30 feet tall. It drips and weeps right to the ground and you can go in under the trunk and you can hide, make a little fort. It’s a wonderful, wonderful understory tree. So it likes a little bit of shade.

Q. How big is the top of it? How tall is the top of it, of the canopy?

A. I think it’s 30 feet.

Q. Oh my goodness. O.K.

A. It’s less than 20 years.

Q. Oh, O.K. because you know when you said weeping. And then I’m like, “Oh, I have one weeping thing.” It’s a ‘Lustgarten Weeping’ kousa dogwood [above].

A. That’s interesting because there’s katsura, there’s one called ‘Pendula’, which only is about— I have that too—it’s about 9 feet tall and it just keeps dripping and dripping like a waterfall. But the ‘Morioka Weeping’ goes straight up and weeps all the way down to the ground.

Q. Oh O.K., because this weeping kousa, you know a kousa can be a medium-sized tree. This weeping kousa, ‘Lustgarten Weeping,’ it does have that little world underneath it, but you would have to sit down on the ground or crawl under. It might be 6 feet tall.

And the reason it makes me think of it because it came in the mail and I got it in the mail from the old Heronswood Nursery. And it had a little sandwich bag and a rubber band around a little tiny ball of soil. It was a rooted graft or cutting or something [laughter], and it’s grown into this big thing. So that’s one. O.K., what else?

A. I don’t know if you’re familiar with the, there’s a couple of black locusts, Robinia pseudoacacia. One’s called ‘Lace Lady’ [also called ‘Twisty Baby’] another one is ‘Contorta.’ And ‘Lace Lady’ kind of grows in tiers almost, like horizontal tiers. That’s not a very big tree and it has a wonderful, dare I say, Japanese effect. You know? It’s kind of a giant bonsai as you were saying.

Q. Uh-huh. I have not been able to sustain any of the Robinia pseudoacacia. Like I wanted to grow that one ‘Frisia,’ the gold one, years ago. And I tried and tried. I have locust borer [above, on goldenrod in the garden]. FYI for people who-

A. Ick.

Q. Yes, I have locust borer. It’s a native insect. It’s everywhere. Maybe it’s not native [update: it is a United States native insect], but nothing I’m going to do about, that so just FYI for that, but they’re beautiful.

A. Well, and if you’re down in that area, maybe you want to see beautiful bark and paper bark maple can’t be beat. It’s the Acer griseum. That’s just so beautiful. Even though you may not see it from a distance or care to. It’s a relatively small tree, but it has just glorious exfoliating bark. It looks like cinnamon curls—you know, like the cinnamon bark?

Q. Yes.

A. And of course there are plenty of Japanese maples, Acer palmatum, some of the larger Japanese maples. And they’re understory trees, too, and they have multi-stemmed effects sometimes. You got me started here. [Laughter.]

Q. Uh-oh. I like the, among the crabapples, I like the ones that have the genetics from Prunus sargentii, the Sargeant weeping crab. I have this one called ‘Candy Mint.’ It’s pink-flowered. So again, assuming you don’t prune off … Some people like to prune off all the long-hanging branches, the weeping branches, because they want to mow under it on a tractor or on a riding mower or something. But I like it when it’s like a whole little world under there. So some of the sargentii, the crabs that have sargentii in it, do that, too. And they’re easy and inexpensive, right? [Above, two ‘Candy Mint’ crabs at Margaret’s.]

A. Right, so now I have to buy another tree.

Q. O.K., good. I’ll send that in the mail to you in a plastic bag, 18 inches. [Laughter.]

A. [Laughter.] Oh, I’m excited.

Q. Other ones? Any other thoughts? Any other crazy ideas?

A. There are some corkscrew willows. There’s a couple of willows. There’s one that has contorted corkscrew branches. That becomes pretty big. But I don’t know if you’ve ever seen that one, sometimes it’s called Ram’s horn, because the leaves are kind of curly.

Q. Yes. Oh, I love those leaves. Yes.

A. Yes, it’s a cool thing, and that’s not a very big tree. And that might be interesting. There’s a weeping mulberry, and those are pretty common, but they can be a little messy. Mine’s never fruited, so it’s not that kind of mess. But the inside branches tend to die, but still that would make a great fort. I don’t know if she’s got kids who want to hide under a tree, but the weeping mulberry is another choice.

Wow, lots of things. How about that Japanese fringe tree? Have you ever grown that—Chionanthus retusus?

Q. I’ve never grown the Asian one. I have a couple of the American ones.

A. And the American ones are kind of shrubby, but the retusus is more of a tree and it has beautiful flowers, and they’re fragrant. I’ve seen that grown in quite a bit of, not a lot of shade, but understory. Because I’m picturing there’s a woodland all around she doesn’t want … she really can’t maybe grow the conifer that she would want—also, it’s slow. I’m sure that you’re pine is not a youngster.

Q. No, no 30 years. They’re 30 years old.

One thing I saw just this last week on, I think it was, I’m pretty sure it was Instagram from a person, a user called IMFederalTwist. He had visited Chanticleer Garden in Pennsylvania, which you know well. And he posted a picture of these crazy willows, Salix alba ‘Britzensis,’ that had been trained to sort of go up and then go sideways and go out, the branches to go up and then out.

And then they had apparently hung stones from the tips of the branches when they were heavy and the branches were sturdy enough to then point them down. So up, out, and then down, to make that kind of crazy, contorted shape.

So trained willows, never had heard of such a thing. Now, a friend of mine said, “Why bother?”

A. [Laughter.]

Q. But on the other hand it looked pretty cool. 

A. You know ‘Britzensis’ we used to grow it as a cutback, because the stems are a fantastic color in the winter. So that seems kind of odd. And I know that person, Federal Twist, is Jim Golden. He has a fantastic garden in New Jersey.

Q. Yes. I follow him so he pointed it out. I don’t know him personally. So since he pointed it out I thought, “Oh, well this is interesting.” I guess the thing about the idea to use willow is that it’s inexpensive, it’s fast-growing, you could shape it.

A. And you can do anything to it.

Q. Kelly could have some more instant things while she waits for some of the more precious things, like the Japanese maple you mentioned. Unless you want to spend $5,000 to get started, it’s not going to be that right away. So you could have some fun things that were a little faster as well.

A. Fun with trees.

Q. Funwithtrees dot com. We’re getting that URL. [Laughter.]

male cones on conifers?

Q. So I have another tree question. Actually this is one that came up, speaking of Instagram—I put a little still-life picture up. I was out walking in the garden last week or the week before and I put a little picture. There were the windfall apples, the tiny little apples that fall when the tree self-thins. All my old apple trees, at this time of year, every time I want to mow I have to pick up all the little tiny apples off the ground first.

And I picked up a bunch of those, and then I noticed that the big umbrella pine, a beautiful conifer, had dropped its male cones onto the ground and they were littered all around the lower branches and around the skirt of the tree. And I picked a bunch of those and I made a little still life, and posted it on Instagram. And I said “male cones and windfall apples.”

A number of people said, “Male cones? What do you mean male cones?”

A. Male cones? [Laughter.]

Q. So do you know anything about that? Did that occur to you that there are male cones?

A. No, because I think cones have to have seeds and that’s female. But I guess those things, which I look at all the time in the spring and then the pollen gets all over my car, they do look like little cones.

Q. Yes, yes.

A. So I guess they’re cones, too.

Q. It was Adam Wheeler, the propagation manager and more at Broken Arrow Nursery—once we were in my garden and I said, “Oh, aren’t those gorgeous?”

And he said, “Those are the male cones.” And that got me looking it up. That’s why I knew that’s what they were called. And I suppose there’s a scientific word, too [UPDATE: the word is strobili, or singular would be strobilus].

But the thing about male cones is they’re herbaceous, they’re soft. They don’t get woody like the female seed-bearing cones. They’re pollen-bearing, and once they give up their pollen, once their pollen is dispersed, they fall to the ground. They’re not needed. Right?

A. Right.

Q. So it’s kind of fun. So I just wanted to say that as a curiosity item. Aren’t some of them … on some different conifers they’re reddish in the spring or they’re purple. You know what I mean? [More on conifer cones from the American Conifer Society.]

A. Gold. Mm-hmm, right.

Q. Yes, beautiful colors, right?

A. You know it’s funny. As you’re saying this I’m thinking of cycads. You know those prehistoric plants that are sort of like palms. And I’ve seen them with what looks like cones, but they don’t have seeds. And I guess those might be the male cones.

Q. I think you’re right because that’s in that direction, those primitive plants.

A. Yes, they’re conifers [specifically they are Gymnosperms like the conifers—seed-bearing vascular plants].

invasive sweet autumn clematis

Q. So a question about clematis from Ann. She says, “How do I get rid of all the sweet autumn clematis [Clematis terniflora, above; photo by Ken Druse]?”

She didn’t know it was invasive. She bought a home that had a great garden, but it’s a bit overgrown. And she like the clematis when she first saw it and now she’s having like “uh-oh” regret because it’s getting everywhere and she’s constantly finding more and pulling it out. Any sort of tactics that we can suggest?

Or is that what to do: pull, pull, pull?

A. I’m constantly finding more and pulling it out and I never planted it, but it’s all over the area here, more and more each year. I don’t know where it’s coming from. But I’m afraid I weed it out; I don’t use a spray or anything. You know you can see it trying to smother a spruce tree or something and just take the top and follow it down and dig it out.

Q. And do you find it self-sows around? Is that what’s happening?

A. Yes, I think so.

Q. Yes. Do you have any other sort of that frothy … It’s such a nice fresh look and I think that’s what people love about it, that sort of froth. Besides I believe it has a sweet smell hence, the sweet autumn. Yes.

A. Oh it sure does. It smells like vanilla and Lysol. [Laughter.]

Q. O.K. Ken! Thank goodness you don’t work for a perfume company describing the scents. [Laughter.]

A. Well, I think about these things all the time. There’s Clematis virginiana, which looks almost exactly like it and, at least in this area, it’s kind of wimpy and sparse. But I’ve read that that can be a problem too.

Q. That’s a native clematis, a white clematis.

A. Yes, that’s a native. It looks almost exactly like it.

Q. So that’s one other choice. Have you ever grown Clematis fargesii or ‘Paul Farges’ [above]?

A. No. And that’s a fall bloomer, too?

Q. No, that’s summer, but you’d think it was the sweet autumn, although not quite as rampant. Kathy Tracey at Avant Gardens over in eastern Massachusetts turned me onto it. It’s one of her favorite clematis. So it has that frothy white look and it scrambles to about 20 feet. You can cascade it over or down a whole hillside of groundcover. Or say you had conifers, even junipers or Microbiota or something covering a hillside bank, you could scramble it down and it would give you sort of an extra lift in the June, July cusp. So earlier, but that same look. I don’t know any others that look like that.

A. No, but there’s so many clematis from spring to fall. Just saying.

Q. There are indeed. There are indeed. So Ann, we want to tell Ann to just keep digging/pulling etc. There’s really no other way.

A. Not that I can think of. But it’s so leathery I don’t even know if a herbicide would affect it too easily. Besides, it usually grows on something else, and unless you’re on a chain-link fence that can’t be hurt by Roundup, you better just keep digging it out.

Q. The other thing is because it does self-sow, if you’re not going to get to some of the bigger, older plants that are going to flower, behead them just before flowering and throw that away. At least minimize-

A. You can cut it right at the ground if you can’t dig it up and even just leave it there. Let it die.

Q. Yes.

harvesting, curing and stashing garlic

Q. Got any questions for me? [Laughter.]

A. You know, that’s funny that you should say that because whenever I think of vegetables I think of you. [Laughter.] And if I have to throw out one more-

Q. That’s nice. He thinks I’m like a vegetable.

A. Wait till I get to this. If I have to throw out one more head of garlic.

Q. Oh, I know.

A. I buy the garlic. I’d love to get the braided garlic, but I can’t use that much garlic, not that fast. And I buy a nice, beautiful head of garlic, you know bulb and then some of them shrivel, some of them start to sprout green. I’ll even use the green sometimes. But how do you … Do I put in the refrigerator? You know the sell these sort of ceramic things to store it? I don’t know how to keep it.

Q. Well, it’s funny you ask about garlic. Well, not funny, but it is garlic harvest time for people who are growing it. Do you grow it in your garden? You don’t really do that, do you? Do you grow garlic?

A. Like one maybe because, again, I don’t have the sun. But I can grow some Allium, so I could probably. I’ve done it in the past, yes.

Q. Because it’s kind of garlic harvest time and readers and listeners in the more southern and western areas. And some of the garlic farms, like Filaree Garlic Farm out in the west, the biggest organic collection of garlic in the country. I noticed on their Instagram and other social media [in early July when we taped this Q&A] that they’ve been harvesting already. So it is time. And so the how your garlic is going to store depends on, like with a lot of storage crops, like winter squash or whatever, it depends on how you harvest it and how you cure it or fail to cure it, right? So getting it ready for storage.

And so one of the key things is that people either wait too long or harvest too soon. If we think about the way a garlic plant looks there’s nothing, just a stem at ground level, but there’s the sheath of narrow leaves up top and there might be 10 of them or something. I don’t know how many there are.

But each one of those is a potential bulb wrapper if we trace that leaf down underground and wrapping around the garlic, around the forming bulbs. You know? So we need some wrappers, that skin we see on our garlic in the supermarket, that white skin, right? We need some, but we don’t want too many. So we need it to reach its maximum capacity of development, but not over-develop and have no wrapper so the bulb isn’t tightly wrapped anymore when we’re trying to store it. So it’s picking the right moment. And so I’m just trying to make people able to visualize.

So most experts say you have to let the garlic tell you when harvest time is. It’s not like “the second week of July,” or “the fourth week of July.” It’s like each year is going to be a little different, watch the plants and usually you harvest when several of the lower leaves have gone brown, but there’s still maybe five or six up top that are still green. So that, again, you have some wrappers still intact, enough good wrappers intact.

And then you need to cure it. Unlike onion, its cousin, you can’t leave it out in the sun, just pull it and lay it on the bed. Like onions you can basically let them practically dry on the ground for a while. You can’t do that with garlic. It doesn’t like to be in the sun once it’s unearthed, it will deteriorate. So you want to put it in a warm, dry, airy place, but out of the direct light. You see a lot time in sheds and stuff. You know what I mean? Like with a roof, like a shade house or something or in the back of a barn people hang it. I put it on racks in my garage, like hardware-cloth racks. Anyway, you want until it really dries down and then cut off the then-dry stem, the long stalk, and some of the roots and stuff.

But it’s that last bit of storage then—it’s counterintuitive. It wants to be warm and dry in the sort of semi-dark just to cure, but then it wants to go at 40-something degrees, no more than 55, with some humidity, 60 to 70 percent humidity. It doesn’t want to go so cold and so forth as the refrigerator. The refrigerator has too much moisture, but it doesn’t want to be in a super-dry place, either. So it’s hard for us in our human houses to find that place. I tend to store it in the upstairs of my garage, Ken, all winter. And it’s like 40, 42 degrees and it’s pretty … I try to keep it, I mean, I’m hoping it’s around that 60 percent humidity. It’s probably a little drier.

But I freeze more than half my crop pretty much right after curing. Do you ever freeze any?

A. The whole bulb?

Q. You could. I find that messy then when you want to defrost it.

A. Right. So you take off the cloves.

Q. I separate the cloves and I peel them. And then I toss them real quick in just a teeny bit of olive oil just to prevent a little freezer burn, and I put them in either Ziploc freezer bags or wide-mouth canning jars in the freezer. You know? Like full cloves and I can just take out as many as I want.

Some people chop it up first and they make a log, like a paste, and they form that into a log, roll that in the bottom of a Ziploc bag. And then they can just cut off a medallion, a disk. Yes, so freezing is great. It’s hard to peel the cloves when they first come out of the ground because they’re so rich in oil, but once they’ve cured they’ll be a little easier to peel.

A. Well I can tell listening to you that I’ve been keeping them too warm.

Q. Yes, again, it could be up to 55ish, but really I find that mid-40s gets me the longest storage. And different kinds of garlic store longer, which is the other tricky thing. Softneck, the kind of that you see usually in the supermarket, with a lot of little cloves, that can store up to 10 months. Whereas I never know how you say it, rocambole, they can maybe only store three, four months.

So it depends on what you’re growing, too. I grow a really large-clove one, maybe five big cloves per head, a hardneck garlic. That’s why I freeze half of it. Half lasts about six months, seven months in storage, but then the rest I’ve got in my freezer for the rest of the year.

Sorry I went on so long, but there’s a lot to it.

A. [Laughter.]

Q. But it’s the two stages of storage. Do you know what I mean?

A. Yes. And I’m going to try a couple of those. As you’re saying that I’m thinking sometimes I’ll wrap something in a paper towel and put it in a plastic bag because that problem with the humidity in the refrigerator, I’ve had that happen. Yes, I’ll try that with a whole bulb and just the big news for me is: don’t leave it on the counter.

Q. Right, exactly. Or at least put it in your pantry cupboard on an exterior wall that’s probably darker and cooler. Do you know what I mean? At least do that. That’s going to give you more extended time than out in the open in the main room.

A. Got it.

great outdoor paint colors for trellises, fences and more

Q. Crazy little question: outdoor paint colors, I get asked over and over again about outdoor paint colors. And people want to know, I’ve had a number of readers ask, are there any sort of good, universal, great colors for things outdoors, whether a fence or actual house or shed or something?

A. Ah! That’s my favorite topic. It’s the “invisible paint,” and I recommend it all the time. Everybody loves it. It’s just a great success. If you want something to recede—if you’ve got a utility area with a fence around it or you even want to paint the garbage can so you don’t see that metallic garbage can I use … It used to be Cabot Stain, but Benjamin Moore makes it, too. The color [still in the Cabot line] is Spanish Moss. It’s the color of dirt and bark. [The formula for the Benjamin Moore stain formerly called Spanish Moss is above, from Ken’s paint supplier.]

Q. [Laughter.]

A. And it’s not a color that I’m really attracted to, but it makes stuff disappear. They put a … I was just going to say the county put a guardrail up where you could see the back of it and it was shiny metal and I painted that with the invisible paint and you couldn’t even see the guardrail. [Above, the bridge at Ken’s garden painted in Spanish Moss; photo by Ken.]

Q. Oh, yes. Well, my house, which people ask about a lot, too, my house is a very, very, very dark olive, like you can’t even quite read what it is. But it’s a very, very, very dark olive. Another good color is Benjamin Moore Tuscany Green [above, on Margaret’s house]. Not that we’re doing a commercial for Benjamin Moore, but just FYI, these are some colors. If people are looking for that type of hide it, but it fits in—it complements, but it recedes also.

algae in the water garden

Q. Time for a really quick question? Algae in the water garden from Jamie. Ken, she says she installed her first pond, little water feature, it’s in full sun and she wants to know about algae, any suggestion for addressing it?

A. Plants.

Q. Floating plants. [Above, Margaret even covers her container water gardens with floating plants, like duckweed and fairy moss.]

A. I know that’s … Floating plants or even water lilies, something that covers the surface just to keep the surface darker. I don’t know if … you know you can add those safe, dark colorants.

Q. The dyes, right? The black dye.

A. And I don’t know … that would help, but that’s not the best solution. But you know, you want to grow plants and you want to increase the oxygen and keep the water moving, too.

Q. So shade the water, shade the water, shade the water [more details on water-garden care]. Well thank you Ken, thank you, thank you. Go store some garlic.

A. We just went … you mean our time is over?

Q. Apparently. [Laughter.]

prefer the podcast version of the show?

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 July 30, 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).