best peas, black walnuts, butchered hydrangeas, strawberries in pots: q&a with ken druse

THE QUESTIONS CONTINUE: In part 2 of the Jan. 16, 2017 edition of my public-radio show and podcast, Ken Druse and I answered listener questions about best peas, gardening under black walnuts, whether butchered hydrangeas will recover, and growing strawberries in pots.

Ken joined me to kick off a new monthly feature on the show: a listener question-and-answer episode. In the first half (transcribed at this link if you missed it) we took questions about shade, night-blooming Cereus, growing peas, and deer damage.

how to ask a question

WANT TO ASK a question for a later show? You can do so in two ways: Find me on Facebook.com and ask a question there, which a number of people did in anticipation of the first Q&A show. Or use the little link at the bottom of any page on this website that says “contact,” which goes to a little contact form.  Very easy. If your question is selected, we’ll email you to set up a taping time on the show.

Background: Ken, an award-winning garden photographer and author of more books than I can count, including “The New Shade Garden” and “Making More Plants,” produced his own “Real Dirt” podcast for 10 years, until summer 2016. The Real Dirt podcast archive and much more from Ken is available on the newly re-launched website KenDruse dot com (below, a look at the homepage) and still available on iTunes, too.

Read along as you listen to the Jan. 16, 2107 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).

q&a: best peas, black walnuts, butchered hydrangeas, and strawberries in pots



Q. It’s me again. Is it you again? Are you there, Ken?

Ken. Are you talkin’ to me?

Q. Yes, I’m talkin’ to you.

Ken. That pea thing…[laughter].

Q. Yes, I think we’ll just continue and we’ll take another caller in a minute, but with the peas question [that we covered at the end of the first half of the show]

Ken. I think her soil was too wet, because it worked for her the first year.

Q. Exactly. And again: the inoculant can’t hurt. It might be a couple of dollars wasted, but it can’t hurt.

I am a Northern grower, and I love the peas from the breeding work over many years of Alan Kapuler in Oregon—who was Peace Seeds, and his kids now are Peace Seedlings

Ken. [Laughter.]

Q. …at PeaceSeedlings dot Blogspot dot com. You can find their catalog there. They have one of the best selections of peas for Northern growers, I think—some really interesting things. Both the snow peas—the flat-podded ones with little peas in them—and the edible-podded [‘Sugar Snap’ etc.] types, and then also what they call the puffer pods. Have you ever grown those?

A. Oh, no.

Q. So it’s called a snow-snap—sort of a big pod that gets puffy, and you see the peas inside, and the pod stays tender and the peas are tender. Peace Seedlings call it a puffer pod, but I guess the technical name might be snow-snap, and they are fabulous.

I like the one ‘Schweizer Riesen’ [I get it at Turtle Tree Seed] and there are quite a number of other ones if people are thinking of growing peas. Peace Seedlings recommends the puffer pod called ‘Green Beauty,’ [above] which is delicious and prolific.

But find ones that are not only matched to your taste, but work well in your area.

Ken. You won’t believe this, but I have trouble harvesting—you would believe that—but if you don’t get the peas when it’s the right moment, you’ve lost it. When I grew those snap peas on the roof, any pods that were too old I would give to my dog, Peter…

Q. Oh…

Ken. …and it was his favorite treat.

Q. I have a neighbor whose dog likes green beans, and whenever I go to see him in season I bring green beans, and that endears him to me or me to him, or however that works. [Laughter.]

Ken. And now I have Pippa the dog, who is not a great eater—and that’s good, because you don’t want a dog that eats everything. She won’t even eat all kinds of cheeses. She won’t eat a pea. [Above, a painting by Ken of Pippa; see more of Ken’s paitings and sculpture on his website at this link.]

Q. She won’t eat her vegetables.

Ken. She eats some sweet potatoes…but you were saying?

black walnut troubles

Q. So let’s take a caller. We have a caller and I am going to guess that I have the name wrong, but that this might be Ruth. Is this Ruth? Hello?

Caller. This is Susan.

Q. I’ll tell you what, Susan, I have gotten both of the last two names of callers completely wrong, and I am sorry. [Laughter.] Where are you calling from?

Susan. Arlington, Virginia.

Q. Aha! I thought you were in Virginia. We had another caller from Virginia today; we must be popular there.

Ken. Susan, would you consider changing your name? [Laughter.]

Susan. Well…

Q. Maybe not?

Susan. Maybe not.

Q. But you do have a gardening question for us.

Susan. I do. We bought our house 15 years ago, and one of the first projects we did was to move a lot of dirt to create a garden in the backyard. It just so happens that it is under a walnut tree. I’ve had a lot of trouble with different plants over the years not thriving.

I’ve recently learned that this plant puts out a toxin, and I’m wondering what I do about it.

Q. When you began landscaping you moved some soil. Even in areas not under the tree, do you have issues with bad performance from other plants that look weak or stunted—or just there?

Susan. No. It’s largely within the dripline of the tree.

Q. Ken, there are black walnuts on my road, but thankfully not in my garden so I feel very blessed that they are down at the other end of the road. Do you have them? [Black walnut photo from Wikipedia.]

Ken. I have them, and I have a problem with all…allo…what is it called—tell me?

Q. Allelopathy—which one botanist described to me as “plant warfare.” Many have plants this trait, where they exude chemicals. It’s part of a defense mechanism that many of our most successful weeds have, too, that they exude a chemical in the surrounding soil that deters other competitors from living in that area. It’s a very clever strategy to have turf that you can be sure nobody else will come and invade.

Ken. Have you ever noticed how there is no grass under the birdfeeder if you have sunflower seeds in it?

Q. That’s another great example; sunflower seeds have that, too. In the black walnut it’s called juglone, and there is also another chemical they exude called hydroxyjuglone—but my goodness, the chemistry is way over my head. So again, it’s chemical warfare by the plant.

The thing that’s interesting to me it that it’s in every single part of the plant. It’s sort of like with poison ivy–how every part of the plant can give you a reaction if you are allergic to it—the roots, berries, leaves, vines, everything.

Ken. The husks of the fruit of the walnut the leaves that fall. I have heard that the roots are the most part, and have the most juglone.

Q. So this is a survival strategy—a land-grab strategy [laughter]—by this plant. And you’re right, it makes it very unattractive to other plants, and gardening around it is challenging. I believe that certain other plants like butternut (in the same genus) have it to a lesser degree, and certain hickories.

Ken. Norway maples are allelopathic, too.

Q. But the black walnuts are the worst. Do you clean up under the plant, all those leaves?

Susan. We do; we take all the debris and actually send it to the county in the bins they give us for gardens. And actually all the nuts, too, so that the squirrels don’t get them.

Q. Yes because it all has juglone in it. It’s then what else to do—you’re not going to take down the tree, and if you did you’d have to excavate….

Ken. Or wait a very, very long time.

Q. So are you seeking things that will do well in that area?

Susan. I have been doing a little research, and the Virginia Extension had some plants that it suggested, and I have gotten some others that seemed to work. Not all the ones they suggested seemed to work.

Ken. Oh, really?

Susan. What I was wondering is if I transplant something that is reasonably healthy into another part of the garden, because I have two big gardens, would that move the toxin with it?

Q. I don’t know, but I think I would be tempted to reduce the soil on the rootball of what I was taking. If it were a herbaceous plant or a bulb, I would wash it. That might be superstitious, but I would. I’m like that with weeds, when I have a weedy area and want to transplant something from that bed that’s desirable, I will bare root and wash the thing, to try not to move the problem.

It is interesting about the list of plants that can tolerate juglone, or compete in that kind of situation. You are making a good point, Susan, by saying you went to your state Extension website. It’s important to do that because soil chemistry is different, even down to the county and local level. So it’s almost an experiment and different states with different soil types have different soil chemistry—which seems to affect who else can compete or not.

So I have seen lots of different lists. What did you try?

Susan. What I tried was lavender, which seems to be doing pretty well. We have yuccas, which I have not seen on the list, but they’re doing well. Helianthus seems to be doing OK, and a couple of different veronicas. I have a lot of seasonal bulbs. The tulips are doing fine, the jonquils not so much.

Q. Interesting.

Susan. So it’s a little of this and a little of that. I had a butterfly bush that totally died, and the crape myrtle seems to be thriving. It’s been a little bit of a crapshoot.

Q. You said the daffodils are on the list that didn’t do OK, and I noticed on a list from Penn State, from their great Extension website—they say daffodils are one that will work. [Laughter.]

Susan. I think it’s certain varieties only maybe.

Ken. Is your soil kind of moist there?

Susan. It’s not particularly moist. It’s on the south side of the house, and has part sun most of the day, event with the tree there.

Ken. I’ve heard that in dry soils it can be worse, and that if you have a moist soil it can tolerate the juglone a bit better.

Susan. I could add moisture.

Q. Turn it into a water garden. [Laughter.] I’m going to include some plant lists that you might want to compare to the one you found on Virginia Extension. Thanks, Susan.

[Update: Though the appearance of wilting in juglone-affected plants may appear worse in hot, dry soils, reports Penn State, sensitive plants will be most impacted in “poorly aerated, wet soils with limited microbial activity and organic matter.” So truly sodden would be no good. Apparently juglone is “poorly soluble in water and does not move very far in the soil.” Best scenario: “Well-drained and aerated soils with a healthy population of microbes [which] can accelerate the metabolic decomposition of juglone.”]

Ken. Hey Margaret, do you know what the Latin name for black walnut is?

Q. I think it’s Juglans nigra.

Ken. And do you know what Juglans means?

Q. No.

Ken. It’s Latin, of course, and it’s actually from ancient Rome, and it’s “glands of Jupiter” or “Jupiter’s glands.” And if you can imagine what part of Jupiter’s anatomy most resembles a walnut, then perhaps we should move on to the next question.

margaret’s most common question

Q. Moving right along here. It’s a tricky question because with soil chemistry it’s not just that the black walnut is there.

I’m still marveling as we talked about in the first segment how your most popular question is night-blooming Cereus. [Laughter.]

Ken. What’s your most popular question?

Q. I used to do the call-in on Martha Stewart’s Sirius Radio channel, and I used to say it was, “When do I prune my (fill in the blank)?” So the pruning questions, and frequently that was lilac, rose, apples/fruit trees, or hydrangeas.

And the other version of that was, “Why didn’t my (fill in the blank) flower?” and the fill in the blank was usually hydrangeas, roses, lilacs—the same plants. And sometimes the answers were related, because sometimes the pruning was done at the wrong time and that was why there were no flowers. That was a really common thread, so to speak.

Ken. But your show is kind of a 2.0 gardening show now—and we use Latin names, and you talk about science, and where the answers to our questions come from. I think it has kind of grown up. [Laughter.] We’re talking to grownups here.

will the whacked-back hydrangea recover?

Q. I had a question from Sheila in Moline, Illinois—she wrote in on Facebook. She said, “My garden guy weed-whacked my hydrangea. Will it come back in the spring?”

See: Hydrangea—I told you hydrangea was a popular thing.

Ken. We could do three hours on that.

Q. Well, OK, but let’s not. [Laughter.]

Ken. The first thing is which hydrangea—and it’s probably one of the macrophylla or mophead types.

Q. I asked her back in the comments on Facebook, and she said it was, so yes. A macrophylla.

Ken. I wonder how close to the ground he whacked it.  I would guess it would come back, but it will take awhile.

Q. But it’s not going to bloom this year because…

Ken. [Laughter.] Absolutely not.

Q. Because the macrophyllas carry their flower buds over the winter on older wood.

Ken. Two- and three-year-old wood.

Q. I’m voting that it will come back, and I have sometimes moved old shrubs by first cutting them all the way down because sometimes they’re too big to move with all their branches. If it has a healthy root system, it does fine.

It’s not exactly how you’d want that to happen, having someone weed-whack it, but…

Ken. If you’re growing a Hydrangea arborescens like ‘Annabelle,’ I cut those back every other year down to about 2 inches, and you get those gigantic heads and often have to stake the stems. Then the second year the flowers aren’t as big, but they will stand up without the staking. I treat that almost like a herbaceous plant, and it does bloom the first season from cutting it back.

But Hydrangea macrophylla, the mophead types? It’s two- and three-year growth [that blooms], and you cut those canes out probably in the third or fourth year [after bloom, removing at the base]. People always prune off the flower buds and wonder why it doesn’t bloom—you know, they “shape” them.

Q. “Shape.”

Ken. They prune them like a hedge and cut all the flower buds off. Instead, cut out the dead stems or the ones that are three or fours years old.

Q. The ones that are past their prime.

strawberries in containers?

Q. So let’s take one more question, which also comes from Facebook—from Karen in Texas. She says:

“I enjoy container gardening with strawberry plants. I keep them on my patio, and thankfully the birds don’t seem to notice them there.”

That’s very good news! She continues:

“What type of container will help me yield the best crop?” She has just been using regular pots, but wonders about whether she should invest in a “strawberry pot” so that some will be hanging down instead of lay on the ground or pot surface. Any tips and tricks for strawberry growing in containers, she wants to know. What do you think?

[Just for fun: Super-ambitious strawberry-growing photo below, prize-winning Chelsea Flower Show display of wall of strawberries, by Darorcilmir via Wikimedia Commons.]

Ken. You’re asking me? [Laughter.]

Q. Well, I have seen pictures and know you have grown some–maybe alpines in containers? I don’t know if those would be good for her in Texas. [Update: Missouri Botanical Garden says alpine strawberries, Fragaria vesca, are hardy in Zones 5 to 9, so technically they can grow in Texas.]

Ken. I do grow alpines, in containers, and they are wonderful in containers. I grew some of the running types in pots, because I don’t like them going everywhere. I also grew some of the strawberries with pink flowers—what are they called, Panda?

Q. ‘Pink Panda,’ yes. [Laughter.]

Ken. And it goes everywhere. So as it produces runners, I’ll take another pot, and take a hairpin and pin the runner baby into that pot, and then I have another plant and then it sends out runners.

[Note: ‘Pink Panda’ is an interesting intergeneric hybrid of a strawberry (genus Fragaria) and a cinquefoil (genus Comarum). More on it here.]

I think that the strawberry pot depends on where you live and how much effort you’re willing to put into it. In my experience those little side parts you never really get watered right. Some parts are too dry; some too wet. They’re very decorative, and if you can do it for a few years you will probably get the hang of it, but I think that’s a little too much work and you won’t get as many strawberries.

Q. And I think with containers in general, and especially in Texas—a warm zone—we’re talking about a small vessel, with little insulation for the roots. Just like we worry about that in the North in winter. It’s going to need a lot of watering…

Ken. And juicy soil, and compost, and I’d say a pretty big pot.

Q. Exactly. I love strawberry jars, and I have a number of them, but I use them for things that are kind of decorative and fun, like little snippets of succulents [above]—like hens and chicks in them. Or in the early spring I put tiny violas in each little pocket, and then it doesn’t matter when it gets hot, because in summer I compost my violas anyway.

With strawberries, which are lusty growers and make offsets as you say—even on a farm, you need to rejuvenate and get rid of the excess plants so they don’t choke each other out and are productive. I think confining it to a small pot is cute and precious—but it’s not the way to get a high yield, and Karen says very clearly she’s looking for yield. I think bigger containers, and to pick varieties suited to her climate.

So we survived [our first Q&A show], Ken. And we’ll get the hang of it.

Ken. And they were tough questions, too.

Q. But there were no trick questions. [Laughter.]

Ken. Well, I don’t know, it was pretty tricky—juglone!

Q. Yes, the chemistry of juglone, and I have lots of backup to share on that. I’m so glad to kick this off together, and thank you as ever for being here, Ken.

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 seventh year in March 2016. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the Jan. 16, 2017 show right here. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).


(Garden photos courtesy of Ken Druse. Purchases from Amazon affiliate links yield a small commission.)

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  1. Louise says:

    With a super overgrown H. Annabelle, 10 feet wide, should I cut it down and dig 3/4 of it out? It doesn’t bloom well and grows quite tall. That would allow me to dig out thorny vines that grow there, too.

  2. Mary Robblee says:

    Garden Gate Magazine referred to black walnut jug lone tolerant plants in the Dec. 2016 issue page 38 and referred to web site Morton Arboretum.org ” black walnut toxicity for more information. Just sitting here catching up on my favorite garden activity – reading about it !

    I really enjoy your radio podcast.

  3. Dianna J says:

    Really enjoyed you and Ken doing Q&A! I’m glad that this will be a recurring theme because I missed Ken and his podcast. This was a great show! Thank you Margaret. I’m always inspired after listening.

  4. Nancy Marr says:

    I’ve been reading your advice about peonies, and realize they would be better at the back of my garden, so I could leave the stalks longer. Can I transplant them? They have been where they are two years now, and all but two bloomed this year.

    1. margaret says:

      Hi, Nancy. Yes, you can. The best time is in fall, and Song Sparrow Farm (home of Roy Klehm, a longtime peony breeder I greatly admire) explains how here. It may set back your bloom as they settle in again, but worth it.

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