“Makes the science of plant processes accessible to home gardeners.” —The American Gardener Why do container plants wilt even when they’ve been regularly watered? Why did the hydrangea that thrived last year never bloom this year? Plant physiology—the study of how living things function—can solve these and most other problems gardeners regularly encounter. In How Plants Work, horticulture expert Linda Chalker-Scott brings the stranger-than-fiction science of the plant world to vivid life. She uncovers the mysteries of how and why plants do the things they do, and arms you with fascinating knowledge that will change the way you garden.
About the Author
Dr. Linda Chalker-Scott has a PhD in horticulture from Oregon State University and is an ISA certified arborist, an ASCA consulting arborist, and an award-winning author. She is Washington State University’s extension urban horticulturist and an also teaches at the University of Washington. Chalker-Scott has published extensively in the scientific literature and in popular magazines including American Nurseryman, Organic Gardening, and Fine Gardening. She also is one of the Garden Professors.
Read an Excerpt
From the Ground Up My first house was in Corvallis, Oregon, home of Oregon State University, where my husband and I were working on our Ph.D. research in horticulture. Our tiny front yard had enough room for a single specimen tree, in this case a lovely ‘Bloodgood’ Japanese maple (Acer palmatum var. atropurpureum). We were eager to update the front entry, and we replaced the 1930s era concrete steps with a basket-weave brick entry and wooden deck. The design perfectly showcased our maple, and we were thrilled with the transformation. Well, until the next year. Suddenly, our maple tree didn’t grow so well. Many of the branches died. Finally, it was in such dire straits that we dug it up and replaced it with a much smaller tree, which thrived. But what happened to the first tree? I asked one of my favorite professors at Oregon State about the sudden demise. Jim Green was our department’s extension specialist and didn’t teach any of my graduate classes. But he was knowledgeable, easy-going, and had a wicked sense of humor. The graduate students loved him. Imagine my shock, then, when he turned visibly angry as I explained our landscaping changes and subsequent tree death. “What in the world did you think would happen,” he snapped, “when you disturbed seventy-five percent of the tree’s root zone in the middle of summer?” Wow. I hadn’t even though about that. We’d dug up the existing lawn and laid down bricks and deck timbers. I remember silently cursing the roots as we dug. And they were probably cursing us back. I felt stupid, not just because I had irked Jim, but because I hadn’t foreseen these consequences myself. After all, I was getting a Ph.D. in horticultural plant physiology! In hindsight, I think this was a defining moment for me, though I didn’t know it at the time. I do know that it was during this time I became more curious as to how plants responded to different environmental stresses (besides dying, of course). Over three decades I evolved from a laboratory plant physiologist (studying how plants function and interact with their environment), to an applied urban horticulturist, and finally to an extension specialist at Washington State University. Though my career continued to change, my interest in how plants work only became more engrossing. I combed through articles on soil science, arboriculture, environmental horticulture, and restoration ecology as well as those in the more traditional botany and horticulture journals. While botany books describe leaves and roots in isolation from each other (and therefore have chapters called “The Leaf” or “The Root”), physiology is the study of systems. It’s impossible to explain the physiology of a leaf or a root, because their functions are influenced by other plant parts. It would be like describing how a heart works without mentioning the lungs that provide the oxygen or the arteries and veins that deliver and return blood. Instead, plant physiology textbooks have chapters on photosynthesis, mineral uptake, and flowering. However, it can be difficult to make these conventional topics both accessible and interesting to the nonscientist. Current books on plant physiology are primarily focused on newer research at the molecular and genetic levels. The content is timely and important, but boy does it turn off your average gardener, who probably sees no practical connection between gene regulation in corn and the corn growing in the backyard vegetable garden. What we gardeners most want to know is how plants work so that we can have gardens and landscapes that are healthy, beautiful, and don’t need constant additions of fertilizers and pesticides. So this book is structured a bit differently. Each chapter opens with a real-life situation, often something in my own garden that I invite you to explore with me. Then I integrate the science as needed to answer questions that gardeners invariably have. I’ve tried to include all of the practical topics that you would find in a textbook, with examples and illustrations to make the science useful and easily understandable. What kinds of things will you discover? We begin at the microscopic level and explore the basic machinery of plant cells, which is substantially different from that of our own cells. Next we explore a vital plant network hidden underground, the root system, which in conjunction with fungal partners seeks out water and nutrients. In chapter 3, we consider which minerals are essential for plant survival, growth, and reproduction and which can be detrimental to these processes. Plants have the unique ability to combine water and carbon dioxide in leaves to produce their own food, and photosynthesis is the topic of chapter 4. Many gardeners live in seasonal climates, and our deciduous trees put on a wonderful display of reds, oranges, and yellows in autumn. In chapter 5, we’ll discover that the plant pigments behind these colorful displays also can help plants retain water, live in salty or contaminated soils, avoid freeze damage, and fight diseases. Yet another pigment is the focus of chapter 6, which describes how plants measure day length to determine when it’s time to germinate, flower, drop their leaves, and close up shop for the winter. We think of plants as sedentary creatures, but in fact they move quite a bit. In chapter 7, we’ll learn how plants move to follow the sun, avoid predators, and even capture food. Unfortunately, these movements sometimes put plants into places where we don’t want them, so we grab the pruning shears. Chapter 8 explores how plants respond to pruning, staking, and other forms of manipulation that we try to impose on them. The final chapter investigates every plant’s ultimate goal: leaving behind offspring to carry their genes forward. Plants produce an amazing array of pigments, fragrances, and seed structures that help them manipulate their environment and pollinators—including gardeners—to achieve this goal. Throughout the book, I’ve included advisory sidebars on which gardening products and practices work and which don’t. You’ll find that many of the products and practices you’ve sworn by for years are not only a waste of money, but may actually harm your plants and soil. Just so you know, I used to buy the same products and follow the same practices, even with my training in horticulture. For instance, did you know that phosphate fertilizer can make plants work unnecessarily to take up water and nutrients? Or that the biggest barrier to getting your new tree to establish is amending the backfill soil with organic material? Think that Epsom salts will nourish plant roots just like they do your feet? Better think again! Understanding how plants work will help you predict what garden products are worth a try and which are best left on the shelf. We often make gardening more of a chore than it needs to be, making decisions about plant care based on how we think plants will respond. Everything from watering to fertilizing to pruning or mowing is dictated by this mindset. Unfortunately, many gardeners make decisions that aren’t just erroneous but may cause actual and long-lasting harm to plants, soils, and the surrounding environment. When you know how plants work, you’ll understand how to use natural processes to your benefit. For instance, proper mulching drastically reduces weeds. Pruning at the right time and in the right place reduces explosions of unwanted growth that have to be pruned again. By using natural plant responses to nurture your garden or to outfox weeds, you’ll have more time to spend watching and learning from your garden, rather than constantly fighting it. I hope you’ll find yourself rereading this book as you explore your own garden with newfound curiosity and fascination. Let’s get started!
Table of Contents
Introduction: From the Ground Up 8
1 Under the Microscope 14
2 The Underground Railroad 38
3 What's Essential 60
4 Transforming Sunlight into Sugar 84
5 Why Leaves Can Turn Red Anytime, Anyplace 106
6 How Plants Tell Time 130
7 Night Shifts and Other Unexpected Movements 150
8 Garden Care, Not Control 170
9 Finding Love in a Sedentary World 196
Suggestions for Further Reading 210
Photo and Illustration Credits 222