Playing Around With Stems

Top Doggery

My pear trees look as if a giant spider went on a drunken frolic among the branches. Rather than fine silk spun in an orderly web, strings run vertically from branch to branch and branch to ground. Yet there is method in this madness. Mine.
As I spell out in my new book, The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden, plants produce a natural hormone, called auxin, at the tips of their stems or at high points along a downward curving stems. This hormone suppresses growth of side branches along the stem, allowing growth from a bud at the stem tip or high point be the “top dog,” that is, the most vigorous shoot.

Within any plant a push and pull goes on between fruiting an stem growth. Both require energy, which the plant has to apportion between the two. The more vigorously growing a stem, the less fruitful it is.

All this talk of hormones and inherent stem vigor is more than academic; it can translate into delicious fruits.

Pear trees tend to grow very vigorously, especially in their youth, with many vertically oriented branches. A certain amount of stem growth is, of course, desirable; leaves are needed for harvesting sunlight for energy and stems are needed on which to hang fruit.
Tied branches in British orchard

Tied branches in British orchard

But pear trees, especially in the youth, tend to put too much of their energies, too much for me, at least, into stem growth. The result is that they can take long time to settle down and begin bearing fruit.

Hence, the strings. I can change my pear trees’ habits by merely tying down branches, reducing the effect of that auxin so that growth is more uniform along a length of the stem. And, as important, slowing growth nudges the energy balance in the direction of fruiting.

Branch bending

The one branch on each young tree that I do not tie down is the main vertical stem, which is the still developing trunk off which grow the main side branches. I want this stem to keep growing upward. Also, I have to be careful not to create a downward arch when tying down any stem. You know why: a very vigorous shoot pops up from the high point in that arch.

More Fruit or More Growth?

Branch bending is not only for coaxing a tree into fruiting. On young branches, it creates a wide angle between a branch and the developing trunk. Wide angles here have been shown to result in good anchorage, sturdy side branches that can carry a weight of fruit.

Suppressing the vigor of side branches also ensures that they won’t compete with the developing trunk, which needs to be top dog.

And using string to play around with plant hormones isn’t needed on every fruit tree. At the other extreme from pear in its growth and fruiting habits is peach. Peach is naturally very fecund, and becomes naturally so at a very young age.

One reason for peach’s fecundity is that it bears all its flowers and fruits along stems that grew the previous season. Every year new stems grow that bear flowers and fruits.             

Beauty, Fruit, and Fun

All this concern with auxin, vigor, and fruiting comes most prominently into play with espalier, which is the training of a tree to an orderly, often two dimensional form. The tracery of the branches themselves adds to the decorative value of the plant.Pear espalier

Fruiting espaliers, besides being decorative, produce very high quality fruit. Pruning and branch bending maintain a  careful balance between yield and stem growth, and the form of the plant allows leaves and fruits to bathe in sunlight and air.

Asian pear espalier flowering

New Book by Lee!

A Book Is Born

            Finally, after all the hard work, I have in hand the first copies of my new book The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden. The Ever Curious GardenerThis book grew out of my long love affair with gardening—such a congenial confluence of colors, flavors, and aromas all seasoned with the weather, whatever pests happen to stop by that year—and the science behind it all!

            And the science behind it all is what this book is about. No, it’s not a comprehensive overview of botany and related sciences. It is some of the natural science that can be applied in the garden. Science may seem out of place in so bucolic an activity as gardening. After millions of years of evolution, seeds want to sprout, and plants want to grow, even in such diverse soils and climates as the Arctic tundra, the Arizona desert, and my garden in New York’s Hudson Valley. So it’s possible to have a decent garden with minimal effort or know-how.

            But with some understanding of what’s going on behind the scenes, and application of that understanding, gardening can be something more than this business as usual, with commensurately more rewards.

In The Beginning . . .

            The beginnings for this book came to me one day as I was piling recently scythed hay and horse manure, along with old vegetable plants and sprinklings of soil and dolomitic limestone, into one of my compost bins. I realized that what I was adding to the pile and how much of each ingredient, even how I fluffed them up or patted them down with my pitchfork, and then watered, all reflected what I had learned over decades of gardening. My classrooms have included actual classrooms; gleanings from magazines, books, and scientific journals; conversations with other gardeners and agricultural scientists; and (most importantly) the garden itself.

            My garden education has been unusual. Growing up in the suburbs, the tenure of our family’s small vegetable garden was soon eclipsed by a swing set.Lee, 1955, in garden Wait! How about that potted banana tree and one hyacinth bulb that I nurtured under the purple glow of a Growlite in the basement during high school? Or the potted cactus that I bought to adorn my bedroom windowsill in graduate school. Hints of future interest? Perhaps.

            Graduate study in those cactus days was in chemistry, a continuation of an interest kindled by my high school chemistry teacher. But coming to the conclusion that graduate study in quantum chemistry was not going to answer any fundamental questions, I dropped out, moved to Vermont, and got the gardening bug. Because I was living in a third floor apartment, I expressed that gardening bug with a voracious appetite for books—books about gardening.

            A year later, I dove into agriculture in earnest, and was fortunate to land in a graduate program in soil science. My interest and education in chemistry proved a good foundation for soil science.

            A small plot of land began my education “in the field” and complemented my academic studies. Lee, 1974, in gardenThe university’s agricultural library offered more books to further round out my education. (I remember coming across a whole book on lettuce seed!)

            Eight years later, with two framed diplomas to hang on my wall, one for a master’s degree in soil science, and the other for a doctorate degree in horticulture, I was still gardening with the same exuberance and learning about gardening through experience, the printed word, and contact with others “in the know.” Thinking back, how little I knew about gardening. And so it goes.Lee, 2014, in garden

A Little Natural Science for a Lot Better Garden

            Back to my compost pile… I took into account the meadow hay’s youthful lushness, which influences its ratio of carbon to nitrogen, as I layered it into the bin along with the horse manure. Manure is usually thought of as a high nitrogen material, but I looked at what was in the cart and, eyeing the amount and kind of bedding (wood shavings) with which it was mixed, made a rough estimate in my head of how much to use to make a good balance with the meadow plants. When the pile was finished, I checked my work by monitoring the temperature of the pile’s interior with a long-stemmed compost thermometer. Etc., etc. There’s art in making compost. But also science.

            With this book, I hope to show how knowing and using a little of the natural science behind what’s happening out in the garden can make for a lot better garden in terms of productivity, beauty, plant health, sustainability… and interest. Knowing some of the underlying science at work in the garden also makes for a more resilient gardener, better able to garden at a new location or in a changing environment.

The Ever Curious Gardener is available in bookstores and online in mid-April, 2018, or now, signed from me, at