I LOVE THE SCIENCE behind gardening, the stories that reveal what makes things tick in the natural world. A new book by Lee Reich called, “The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden,” is loaded with such stories.

Lee Reich, or should I say Dr. Lee Reich, has degrees in chemistry, soil science and horticulture, and is author of many previous books including, “Landscaping With Fruit,” “The Pruning Book,” and “Weedless Gardening.” The topic of our recent conversation was more about wondering and explaining not just the how-to, but the why and how things happen, including: ways to know your soil better, to propagate bulbs by understanding their physiology, or nudge fruit trees not to skip a year of bearing fruit and more.

Read along as you listen to the April 23, 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).

Plus: Enter to win a copy of the new book, in the comments box at the very bottom of the page.

natural science in the garden, with lee reich

Q. Lee, congratulations of course on the new book, but knowing you all these years and your academic background, I wonder if this was the book you’ve sort of always intended to write and you finally got the chance to?

A. Well, I did intend to write it for a long time, and so I’ve been thinking about it a lot. So the answer’s yes. [Laughter.]

Q. Because it seems just like, I mean you know the fact of using science for a much better garden kind of seems just like you, and the “ever-curious” part. “The Ever-Curious Gardener” is how I would think of you. So, yes, O.K.

A. Right, and it did hit me as I said, repeatedly it was hitting me as I was doing things in the garden. A lot of what I had learned in my academic settings have really influenced what I was doing.

Q. Right. The book has so many different little stories, lots of different stories, so it’s not like a textbook. They’re not turgid and academic, they are kind of fun and they have that human part. Like you said, you learned from what you were doing and you drew on your academic background to enhance what you were doing and so forth.

There were a lot of terms in it, you know obviously, some of the sciencey words and there were some fun ones that I knew, like “double dormancy.” I’ve used it myself, but I didn’t know until I read in your book what the “double” is. What’s double dormancy for instance?

A. Well that could be,, for instance tree peony seeds. They have a double dormancy, it means you have both dormancies have to be overcome before the plant can respond. So tree peony seeds have a double dormancy. One is for the root to grow first, which makes sense. Then the second dormancy is for the shoot to grow. Basically obviously in nature they don’t read textbooks, but they just do it naturally, but it might take two years for a peony seeds to germinate. If you know about double dormancy you can do it sooner.

Q. You can outsmart them. Again, I knew what it was and I knew some plants that had it, and that you had to outsmart it, but I didn’t know what the “double” referred to. That it was two aspects of its growth.

A. Right.

Q. Yes so that was interesting. Then there were words like, I’m not going to probably say this one right, totipotence, T-O-T-I…

A. [Laughter.] You did not say it right.

Q. T-O-T-I-P-O-T-E-N-C-E.

A. Right, totipotence. [Laughter.]

Q. Totipotence.

A. All-powerful.

Q. And what the heck is that?

A. Actually that’s one of my favorite ones, because it highlights the fact all cells in any organism, except for the reproductive cells—the sperm cells and the egg cells—have basically all the genetic information needed to make any type of cell. So even in humans, a cell in your eyeball is genetically the same as the cell on your skin, but just where it develops and how it develops makes skin versus an eyeball.

It’s the same with plants, every cell, except for the egg cells and the sperm cells, have all the information to make any part of a new plant. In plants, you can actually use this to, well a lot of people do this when you take a cutting. A cutting is just a stem, and then you take a cutting and you root it and that thing that was once a stem can become a tree. Where it has roots, has leaves, has flowers, and has fruit. Basically everything happens there.

Which is one reason I really like propagating plants. I’m sort of addicted to propagating plants just because I have done it so many years with so many different plants, but I still find it so fascinating. You can just make whole new plants out of just a part of a plant. You can even do it from a few cells of a plant.

Q. Right, like a tissue culture practically right? Cloning.

A. Yes.

Q. So say the word for us again that is the all-powerful.

A. Totipotence. [Laughter.]

Q. Totipotence.

A. Totipotence.

Q. Didn’t know, never heard it, love it.

A. It would be more effective if I said all- powerful, that has a bigger impact.

Q. Yes. The thing about this new book, about “The Ever Curious Gardener,” is that it’s not just knowledge for knowledge’s sake, but as you were saying before, it’s useful insights. It’s problem solving. So for instance, there’s one section about bulbs and how understanding the structure of a bulb can help you to propagate it. Can we talk about that a little bit because that’s not something that I knew, either?

A. Yes, people take bulbs and they plant them out and eventually they might get crowded and you get new bulbs and you can separate them. But if you realize that a bulb is basically a stem compressed down, and the scales of a bulb, like onion scales, those are actually modified leaves.

So a bulb is a stem that’s telescoped down, and on a stem where each leaf is attached, there’s a side shoot. If you pinch out the tip of a stem those side shoots start to grow. A bulb, similarly, if you can sort of pinch out the tip of the bulb, side shoots will grow where the leaves are attached, which is the stem base of the bulb. Or stem plate it’s called. Then you’ll get a whole bunch of new bulbs quicker.

So the way you can sort of, you might say pinch out the tip of a bulb, is if you just take like a melon scoop or a knife, and just scoop out the bottom that gets out the tip. Then you plant that bulb, and when you dig it up you’re going to have like 60 new bulbs there. Small ones. [Above, scooping out the stem or basal plate.]

Q. So that plate at the bottom that we think of as where the roots are going to come out because we would order a tulip or whatever and a daffodil and it’s kind of dry and it doesn’t have any topgrowth, but it has that—is that a basal plate, is that what’s down there? A plate?

A. Right the basal plate, that’s where the roots come out, but above it is the tip of the compressed shoot.

Q. O.K., and so underneath there we’re going to do what? We’re going to take a melon scoop—I’m trying to visualize, we’re going taking a melon baller and we’re scooping.

A. Well I’ve done it with a knife [above], where you just sort of take out that cone-shaped hole in the bottom there.

Q. Oh.

A. That’s one way to do it, and another way is to just make cuts into it. If you had it upside down you would cut straight down into it like pie-shaped sections.

Q. Oh, like score it?

A. Yes and then you just leave it and replant it. Then you get all these bulblets that form. Then you take those out and you replant those.

Q. So the injury, so to speak, that you inflict, causes it to do this?

A. Right, just like when you pinch out the tip of a growing shoot and it lets side shoots develop, which is another discussion in the book, about how stems grow.

Q. Now, how long does it take for these bulbs to make these baby bulbs in this sort of injured area?

A. Just a one-cycle thing. If you injure it, you plant it, then when you dig it up you got a whole bunch of little ones.

Q. Then those will take a couple of years or a few years to mature right? To flower?

A. Yes, because the bulb has to get enough energy to flower. [Baby bulbs, above.]

Q. Oh interesting. I’m sorry, I interrupted you, so we can use these kinds of inferences of what part of the plant is this, in how you do other forms or pruning?

A. Right. Yes and the section I had on bulbs, I had in the stem section because a bulb is essentially a stem. In the stem section I also talk about ways you can redirect growth in a plant in the stems, where it’s more obvious. Where you can pinch out the tips or cut back stems, and it actually stops the flow of a hormone that goes down the stem, that suppresses growth of side shoots. If you want side shoots to grow, you cut back the tip and then you get side shoots developing.

Q. Now with these bulbs we’re talking about true bulbs, we’re not talking about tubers?

A. Right.

Q. So we’re not talking about dahlia tubers?

A. True bulbs like daffodils and hyacinths. But not things like potatoes or …

Q. O.K., no potatoes folks. [Laughter.] I have a potato growing in my pantry closet that I just found. I’m doing an excellent job by the way Lee, you’d be very proud of my horticultural abilities.

A. [Laughter.] Is that where you cultivate them?

Q.  No I didn’t mean to. I forgot about it all winter. [Laughter.] Suddenly there was like this pink arm reaching over some other things in the pantry closet and I was like, “What’s that?” Looked like a spider.

A. Yes, it’s especially eerie if it’s in the dark.

Q. I know, it’s really funny. There was a section about soil and you of course studied soil science as one of your multiple academic degrees. You were kind of a soil scientist at one stage in your life officially, right?

A. Right.

Q. There’s a section about hand-texturing soil. Can you tell us about that because that was a real revelation?

A. The mineral part of a soil, which is the bulk of a soil, can be made up of various-sized particles. So if they’re large particles, it’s a sand, which you can actually see the grains. At the other extreme, if they’re very, very, very small particles, they’re clay. And if it’s something in between its silt. Every soil is not either a sand, silt or clay, it’s made up of one or more of those three components.

It’s useful to know what kind of soil you have, because clay soils you manage differently and they have different inherent fertility than sandy soils. If you look in my book also I have what’s called soil triangle, which just gives a name to, depending on the ratio of sand, silt and clay.

You may have a clay sand, you could have a loam. A loam by definition expresses equal parts of the sand, silt and clay, which doesn’t mean it has equal parts, but it means the expression of equal characteristics of sand, silt and clay. That’s really among the ideal soils.

So it’s useful to know what kind of soil you have, and the way you can do it is you take some soil and you just wet it a little. So like if you were a kid trying to make clay, but mold it. Then you sort of press it out between your thumb and your forefinger and it’ll make a ribbon [illustration above]. As you might guess, if it’s a soil that’s very high in clay, that ribbon will really stick together like modeling clay would. It’ll make a long ribbon.

If it’s high in sand, which doesn’t really stick together very well, it’ll just drop off. Also, you can feel it, like a silt and soil mix feels sort of silky, and the sand feels gritty. Also, when the soil is dry you can feel it, clay when it’s dry will be, the particles are hard to get apart. It’s like concrete. Sand when it’s dry doesn’t feel that different from when it’s wet.

These are just ways that you can actually—and  I’m not super-good at this, but people that are trained in this and spend their lives just examining natural soils, this is one way they can hone down pretty closely the amount of sand, silt and clay in the soil.

There’s other ways to do it, too. Another thing I talk about is a sedimentation test, which is easy to do at home. Basically you mix the soil with water, and by timing it according to directions of how fast things settle you can determine it that way. The easiest way is you just send your soil sample in for a soil test and you’ll get the results back, it’ll say what it is.

Q. Right, so the one with the, you said sedimentation.

A. Sedimentation.

Q. So because the heavy sand particles would drop out soonest, I assume.

A. Right they drop first and then silt drops next, then the clay.

Q. Yes, but the ribbon, making the ribbon. I think there’s something to be said for hand texturing even if you don’t get it exactly right or you’re not super-expert at doing this with this small, what it’s like a tablespoon or two. A couple of tablespoons?

A. Yes.

Q. …that you’ve moistened, and doing it, if you imagine doing that, you’re going to as you said, get to know better really what your soil is like even if you don’t get an exact percentage.

A. Right, yes, it’s just another one of these things in gardening besides observing the plants and thinking about and reading a lot. Just doing all these things makes more of a connection and makes you a better gardener, and I think makes gardening more interesting.

Q. know I have some very old apple trees, probably 125-plus years old. That you’ve come and visited. They still fruit and so forth, but they tend to fruit in alternate years or at least heavily in alternate years.

I read something in the new book that talked about that you do thinning [above]. You’re a great fruit grower of many different kinds of things. You had some insights. You mechanically remove some of the crop before it grows too big and that there’s some insights from that into alternate-bearing apples and how they needn’t necessarily be alternate-bearing. Can you talk about that a little bit?

A. Yes and first the science behind that’s very interesting and very simple at its grossest level. Inside a fruit there’s seeds, and developing seeds in a fruit put out this hormone that actually suppresses flower-bud formation. The way apple trees and many other trees, most other fruit trees, is they make the initials for flower buds the season before the buds open. So this summer apple trees will set down the initials for flower buds that will open next year.

So getting back to the seeds, if you have a lot of seeds in a fruit, let’s say you have a very big crop this year, that means you have a lot of seeds, which put out a lot of that hormone, which suppresses flower-bud initiation. That means next year you get very few, so some apples especially, I have one apple that a lot of people are familiar with, it’s a great tasting apple, Macoun. That tree is known for alternate-bearing, so some years there’ll be a feast, and some years there’ll be a famine.

The most obvious way to sort of even out that feast-and-famine cycle is to remove some of the seeds, which doesn’t mean you start picking fruit and picking the seeds out.

Q. [Laughter.]

A. It means you reduce the crop-

Q. This year?

A. Yes, and one way to reduce the crop, which is one function of pruning, is just when you prune, you prune out branches that potentially were going to flower and fruit, so that reduces the crop. Often on apples especially it’s not enough, so then while the apples are sort of marble -sized, go along and you pick off some fruits.

It turns out that for a full crop of apples, you only need 5% of the flowers to set fruit. You would like to have maybe say 5 inches between the fruits. Each apple flower bud opens to five flowers, so you can imagine and sometimes the flower buds will be only a couple inches apart so you can have a lot of flowers on the plant.

Then the final important thing about thinning the fruits is that the earlier you do it, especially with apples, less so with other fruits—the earlier you do it the more the effect. If you wait too long then flower buds have already been initiated through the summer, so you want to do it early enough. There’s other benefits to thinning besides just stopping the feast and famine. It actually puts more energy into the plant, into fruits that are remaining so that they have more flavor.

Q. Interesting. Some of mine sort of self-thin, so to speak, like clockwork. Do you know what I mean? They kind of drop apples.

A. Oh yes, well that’s another thing, the apple trees are not stupid [laughter], and what they do is early in the season, there’s a lot of things that can knock off the fruits. There’s certain insects that come out early in the season; there’s late frost. The plants have evolved to actually set a lot more fruit than they even want to finally mature with.

So what happens in apple trees and a lot of other fruit trees is it’s called June drop. They set all that fruit, they know it’s extra fruit, then they got the wherewithal to shed a lot of the fruits, which they do in June. Unfortunately, they’re shedding it not enough for good eating quality for us or necessarily even bloom every year. So we’ve got to come along and thin out some more.

Q. I guess I’m wondering what sort of crazy mad-scientist experiments are going on over there at Lee Reich’s farmden, half-farm, half-garden? Are there things that you’re delving into more deeply now that you’re trying to learn about whether they’re in this book or not? You know that you’re interested in particularly?

A. Well it seems like there’s always things like that. Charles Dudley Warner, who wrote a great book in the 1800s called, “My Summer in a Garden,” which is not totally a gardening book, it’s somewhat political also.

He wrote that some, I don’t have the quote exactly, but basically what it says is that some gardens are given over to experiments so all they get—you don’t get anything, but you get the experiment. So I always have to restrain myself from that because I’m always testing this, testing that.

‘I  HAVE SEEN gardens which were all experiment, given over to every new thing, and which produced little or nothing to the owners, except the pleasure of expectation. People grow pear-trees at great expense of time and money, which never yield them more than four pears to the tree.’—Charles Dudley Warner

I remember when I started gardening and I didn’t know anything about potting soil so I wanted to make my own potting soil. I had visited Eliot Coleman, the well-known gardener, he’d tell me what he does. Then I started reading every book there was on potting soil, every section of every book on potting soils. Then I started of course making up different mixes myself to see which one worked best, which other people had done also. So I don’t know why I was doing it exactly, no need to reinvent the wheel. Anyway, that’s sort of the way my gardening goes.

Q. [Laughter.] Yes.

A. I’m sure there’s something, but of course, put on the spot here I can’t figure out what it is.

Q. O.K., no, no, but so the experiment—I love that; I mean I love that. And I’m glad that you wrote the book because again, it really to me it’s very much who I think of you as being, “The Ever Curious Gardener.”

enter to win ‘the ever curious gardener’

I’LL BUY A COPY of Lee Reich’s latest book, “The Ever Curious Gardener,” for one lucky reader. All you have to do to enter is answer this question in the comments box at the very bottom of the page:

What aspect of natural science in the garden are you the most “ever curious” about? (Lee confesses a lifelong fascination with propagation; I suppose I’m most interested in the insect and other animal inhabitants and their life cycles.)

No answer, or feeling shy? Just say something like “count me in” and I will, but of course a reply is even better. I’ll pick a random winner after entries close at midnight Tuesday, May 1. Good luck to all; US and Canada only.

more from lee reich

• Our past conversations range from blueberry growing to paw paws and growing figs and more
• Lee’s website

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 the April 23, 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).

(Photos from the book, provided by Lee Reich and used with permission.)