The Science of Gardening

Course No. 9443
Professor Linda Chalker-Scott, Ph.D.
Washington State University
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4.5 out of 5
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Course No. 9443
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What Will You Learn?

  • Learn how to discern science-based information from gardening myth.
  • Discover how science provides the best information for developing a sustainable garden.
  • Review how to inspect a tree or shrub to determine its physical condition.

Course Overview

Where do you turn for gardening information? To the salespeople at your local home-improvement store? To the “expert” who has never lived in your part of the country? To the Internet with its latest 100%-effective home remedy pest-control mixture? If those are your sources—and they are for so many home gardeners—chances are you haven’t been entirely satisfied with your results. That’s because so many gardening “how-tos” are simply wrong for your particular garden, while other well-established “how-tos” are wrong for the long-term health of any garden.

The Science of Gardening shows how to create a beautiful and sustainable home garden guided by the newest information from applied plant physiology, biology, soils science, climatology, hydrology, chemistry, and ecology. From choosing and purchasing your trees and shrubs, to giving them the best start in your garden, to healthy maintenance and pest control, award-winning horticulturist Linda Chalker-Scott of Washington State University shows why science-based decisions are always best for your home garden, and also the most ecologically sound for the greater environment. You’ll enjoy her contagious enthusiasm and wonderful sense of humor as you learn to create your own vibrant, sustainable landscape.

In these 24 lectures—enhanced with beautiful photographs, videos, and illustrations both in the studio and in the field—you’ll learn how to:

  • Assess your site’s topography, microclimate, and soil chemistry before choosing a tree or shrub species, and understand why that information is crucial to long-term success.
  • Inspect nursery plants from the crown to the ground for evidence of quality and health.
  • Estimate a specimen’s root health based on above-ground clues.
  • Water your landscape effectively and appropriately, with conservation in mind.
  • Choose an appropriate mulch type by understanding the science-based pros and cons of each.
  • Prune your trees and shrubs safely and effectively based on their morphology and physiology.
  • Identify plant stressors and predict future problems.
  • Manage the weeds and pests in your garden without immediately turning to herbicides and pesticides.
  • Choose trustworthy sources of plant-science information, keeping in mind the critical difference between correlation and causation.

Integrated Pest Management

Professor Chalker-Scott covers gardening from soil and seed to pruning and produce, focusing on the issues and obstacles every gardener faces. And every garden has pests, whether weeds, animals, or both. And let’s be honest: Some days it’s pretty tempting to just buy that bottle of pesticide to solve what feels like a never-ending problem. But building a beautiful landscape doesn’t happen overnight, and neither does pest control. Your safest and most effective long-term approach is to develop an integrated pest management (IPM) plan that addresses your plant and soil needs, the biology and needs of the pest, your tolerance level for garden intrusion, and concern for the surrounding environment. Professor Chalker-Scott devotes two full lectures to pesticides and pest treatment as very few home gardeners are familiar with diagnosing the issues and the options available to them.

The Science of Gardening provides a four-pronged approach for understanding and managing pests of all kinds—from English ivy to deer and everything in between. Your first step is to accurately identify the pest and its physiology, food requirements, and reproduction. With an IPM, the gardener then considers four categories of action in the following order: cultural, mechanical, biological, and chemical. Cultural options include making the plant or the environment less hospitable to the pest. Mechanical options can include weeding, fencing, water blasting, or traps. Biological control requires a deep knowledge of the species involved and careful planning to avoid inadvertent consequences that are worse than the initial problem. And if do you need to turn to chemicals as a last resort, this course gives you a step-by-step guide to choosing and using the appropriate chemicals in the safest manner.

Busting the Myths of Home Gardening

Professor Chalker-Scott describes today’s gardening world as a “Wild West” of products and practices that exist in an almost regulation-free environment. Consequently, we need to look for supporting scientific evidence before making decisions with far-ranging effects.

Understanding the physiological and chemical mechanisms by which your tree or shrub interacts with its environment is crucial for determining how to support the health of your garden. You’ll learn how and why your plants rely on bacteria and fungus in the soil—and how the application of unnecessary gardening products can disrupt those crucial pathways. You’ll also learn why some species of plants grow exceptionally well with certain fungi, forming a symbiotic relationship where the chemical products of one become the nutrients of the other.

As you learn more about science-based gardening, you’ll be empowered to bust some long-term gardening myths. For example, you might have heard you should never shop at a nursery where some plants show evidence of insect damage. The truth: If there’s no insect damage on their plants, it most likely means they’ve been using far too many pesticides. And what about native plants? They will always do better in your garden than non-natives, right? Probably not, because unless you live in the middle of a completely undeveloped area, your garden today shares very few soil, water, and microclimate characteristics with the environment in which that native species developed.

In The Science of Gardening, you’ll learn the truth behind many longstanding myths surrounding gardening. At best, they are wasteful. And at worst, they’ll harm your plants and the environment. They include well-meaning but inaccurate advice such as:

  • Always put gravel in the bottom of a pot because it helps with drainage.
  • Never disturb the root ball of a tree or shrub you’re planting.
  • Use fertilizers when you plant bulbs, perennials, trees, or shrubs.
  • Use organic fertilizers because they’re safer than synthetics.
  • Your soil should contain a great deal of organic matter, otherwise it won’t be healthy.
  • Use a vitamin B-1 supplement because it enhances root growth.
  • Choose only mulches containing organic materials If you want the mulch to be effective.
  • Replace your turf with xeriscape; it will always save you water.
  • Apply a wound dressing after branch removal to help the tree heal.

When scientists examine home gardens and landscapes, one fact stands out: The leading cause of landscape failure is not disease and it’s not pests—it’s our own gardening practices. The Science of Gardening shows you how to make the best possible decisions on plant selection, planting, and maintenance. From now on, you won’t need a green thumb to get your garden to grow; you’ll have science on your side!

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24 lectures
 |  Average 30 minutes each
  • 1
    Garden Science: Weeding Out the Myths
    How many of your horticultural practices are based on anecdotal evidence from your neighbor or grandmother, and how do you assess their validity? In the midst of an unregulated “Wild West” of gardening products and practices, you can learn to access science-based information to create your sustainable dream garden. x
  • 2
    Site Analysis: Choosing the Right Spot
    Many of us make our landscape choices based on plant aesthetics. Instead, learn to first identify your location's topography, prevailing winds, hydrology, soil type, and other environmental factors. Then you'll be able to choose a plant well-suited for the long term. And you'll avoid season after season of frustration. x
  • 3
    Soil Analysis: What Makes Soil Great?
    Unless you live in a completely undeveloped area, chances are your home garden soil is not native. Learn what makes a “great” soil and how to determine your own approximate amounts of clay, silt, and sand; texture; nutrients; pH; and more—before you purchase that “must have” soil addition from the gardening store. x
  • 4
    Living Soils: Bacteria and Fungi
    Just as humans cannot grow without our supportive microbiome, neither can plants. Plant roots, bacterial sheathes, and long filaments of fungus all function together to support the plant's growth, enhancing the uptake of water and nutrients and improving soil structure. But what happens to this crucial symbiosis when you add unnecessary fertilizers? x
  • 5
    Plant Selection: Natives versus Non-Natives
    Native plants are always a better home-garden choice than non-natives, right? We know they are best suited to thrive in the soils and ecosystems of the area, and will create the best wildlife habitat. But does garden science support those “truths”? You might be surprised to learn how introduced species can enhance your garden and landscape biodiversity. x
  • 6
    Plant Selection: Function and Form
    In addition to its aesthetic value, your landscaping can provide privacy, protect soils from erosion, moderate temperature, manage storm-water runoff, provide wildlife habitat, and more. Learn how to select the appropriate plants with respect to morphology, growth rates, and physiology to help achieve your specific goals for various locations on your property. x
  • 7
    Plant Selection: Finding Quality Specimens
    Half the battle of successful landscaping is starting with the healthiest specimens—not, as we sometimes prefer, the largest. Learn how to inspect nursery plants from the crown to the ground for evidence of quality and health, and how to estimate root health by checking for suckers on single-trunk trees, root flare, surface roots, and the “tippy test.” x
  • 8
    Soil Preparation and Protection
    “Don’t plant before you fertilize!” Chances are you’ve heard that admonishment more than once. But gardening science has revealed that many popular practices—including fertilizing every time you plant—are neither necessary nor sustainable. Learn about a more natural way to add organic material to your garden to protect soil structure and nourish your plants. x
  • 9
    The Truth about Mulch
    Learn about the wide variety of mulch types—from glass to wood to compost—and the science-based pros and cons of each. By considering your specific site conditions and personal aesthetics, you can blend a variety of mulches to transform a struggling landscape into one that’s healthier and more sustainable. x
  • 10
    Planting for Survival
    Current research supports the need to radically change the way we’ve been planting trees for the past half century. Although considered controversial by nursery professionals, learn why plant science supports the “old” method of bare-root planting. This technique can improve tree survival because a vigorous root system will better support a healthy crown. x
  • 11
    Aftercare for New Plants
    Once your new plant is in the ground, how should you take care of it? Learn the basics of watering, mulching, fertilizing, staking, and pruning newly transplanted trees or shrubs—and why this care might change in subsequent seasons when the plant is well established. Not sure if your newly planted tree is experiencing healthy root growth? Try the wiggle test. x
  • 12
    Plant Nutrition: Evidence-Based Fertilizing
    The goal of fertilizing is to match your soil and plant needs—micro- and macronutrients, and other chemical requirements—with the appropriate sources of nutrition. By understanding your specific soil test results, you can determine which nutrients are deficient, which might already be present in toxic quantities, and whether or not to buy organic. x
  • 13
    The Art and Science of Pruning
    Have you ever seen a tree cut painted with tar or another sealant? Or seen a crown chopped completely bare? Both are common practices that we now know are harmful to the plant. Using applied plant physiology and science-based guidelines, learn the best timing and methods for pruning that will lead to healthy tree growth for the long term. x
  • 14
    Creating Safe Food Gardens
    While it seems intuitive that vegetables grown in your home garden will be safer and healthier than those purchased at the supermarket, that could be a dangerous assumption. Does your garden soil contain elements of concern, especially cadmium or lead? If so, learn how to best respond—whether in plant choices or creative garden design. x
  • 15
    Water-Wise Landscaping
    Learn how to reduce water use and protect water quality using knowledge of plant biochemistry, transpiration, and photosynthesis. Designing garden modifications, choosing appropriate plants based on morphology and color, and incorporating shading and mulch to reduce evaporation are just some of the water-wise techniques that will help conserve water. x
  • 16
    Diagnosing Diseases and Disasters
    The most common cause of death for home garden plants is poor horticultural practices, not disease or pests. With this step-by-step guide to diagnosing plant problems, you’ll learn how to appropriately remedy any problem—and when the plant will heal on its own. You’ll also be able to identify the warning signs of future problems, so you can treat the issue before it’s too late. x
  • 17
    Gardening CSI: Case Studies
    Take a virtual field trip to see examples of unhealthy plants and learn how to diagnose their problems based on the science of plant physiology. You'll see tree girdling, plants that become smaller over time instead of larger, scorched shrubs, and more. Once you understand the physiology behind these problems, you'll be better able to diagnose and treat any of your garden's plants that might be failing. x
  • 18
    Integrated Pest Management
    There is no lack of chemicals to get rid of the pests in your garden—whether that pest is a plant, insect, or other organism. But for long-term health, integrated pest management provides a better, systematic, science-based approach with a minimum of chemical inputs. With IPM, the goal isn’t to eradicate the pests, but to identify your tolerance level for their presence and implement appropriate management techniques. x
  • 19
    Understanding Pesticides
    Yes, there can be an appropriate time for judicious use of chemical pesticides in your garden—as a last resort to solve specific problems. Learn why you should always stick with those approved by the EPA and your state department of agriculture, and never use the home remedies promoted on the Internet or in non-science-based books. Are organics always safer ecologically than synthetics? You’ll be surprised. x
  • 20
    What to Do about Weeds
    If you have a garden in the U.S., chances are you're familiar with the damage caused by English ivy, kudzu, purple loosestrife, and/or the tamarisk tree. Each of these hardy plants can quickly create a monoculture, driving out other plant species and limiting the availability of diverse animal habitat. Learn the best science-based mechanisms to control these plants. x
  • 21
    What to Do about Insects
    Before you resort to chemical sprays—which can kill all insects, not just the pests you’re targeting—learn how to manage insects by increasing plant diversity, establishing “trap” plants, and using repellents and tools including your basic garden hose. But before you do anything, know your “enemy.” Understanding the life cycle and reproductive physiology of the insect will help you make the most effective management choices. x
  • 22
    What to Do about Herbivores
    You could spend a lot of money trying to keep slugs, rats, moles, rabbits, squirrels, deer, and other herbivores out of your garden. But most of those purchases would have little, if any, value, especially if feeding pressure is high in the surrounding habitat. Learn about the few options that are both safe and effective. And remember, “man’s best friend” might be your garden’s best friend, too. x
  • 23
    Tackling Garden Myths and Misinformation
    If you can't trust the Internet home remedy or the local gardening salesperson, whom can you trust? Make science-based gardening decisions by assessing the credibility, relevance, accuracy, and purpose of the information you read. Learn to understand the significant role played by peer review, the crucial difference between correlation and causation, and how to watch out for over-extrapolation and misapplied science. x
  • 24
    Applied Garden Science: Success Stories
    Two specific transformation stories—a wetlands restoration and a home garden project—reflect the benefit of science-based planning by considering soils, temperature, sunlight, moisture, water table, and likely pests. Learn how to become a citizen scientist and contribute to the field, not by looking for the easy way out, but by asking the hard questions and knowing how to assess the strength of the answers. x

Lecture Titles

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What's Included

What Does Each Format Include?

Video DVD
Instant Video Includes:
  • Download 24 video lectures to your computer or mobile app
  • Downloadable PDF of the course guidebook
  • FREE video streaming of the course from our website and mobile apps
Video DVD
DVD Includes:
  • 24 lectures on 4 DVDs
  • 240-page printed course guidebook
  • Downloadable PDF of the course guidebook
  • FREE video streaming of the course from our website and mobile apps
  • Closed captioning available

What Does The Course Guidebook Include?

Video DVD
Course Guidebook Details:
  • 240-page printed course guidebook
  • Photos and illustrations
  • Suggested reading
  • Questions to consider

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Your professor

Linda Chalker-Scott

About Your Professor

Linda Chalker-Scott, Ph.D.
Washington State University
Linda Chalker-Scott is an Extension Specialist in Urban Horticulture and an Associate Professor of Horticulture at Washington State University. She received her Ph.D. in Horticulture from Oregon State University, focusing on environmental stress physiology of woody plants. She has worked at Buffalo State College and at the University of Washington, where she remains an affiliate faculty member. In addition to her academic...
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The Science of Gardening is rated 4.5 out of 5 by 61.
Rated 5 out of 5 by from This Course Is Wood Chip Mulch for Thought Initially I wasn't sure about what I was viewing and how I felt about it, but then I recognized that this course is basically theory-based, which allows listeners to apply concepts to their particular region and home landscape. If you are looking for grab and go tips, this isn't the course for you. Stick to blogs and Google searches. But if you can take the time to listen and learn what Professor LCS is teaching, the course is valuable. If I had watched this course a few years back, I could have saved myself a lot of money and eliminated some of the sadness and discouragement of dealing with dead and dying trees and shrubs. Although I consider myself well-educated, a few segments of a few of the discussions were a bit above my head, but it's certainly better than a dumbed-down course that left me wanting more. My only suggestion would have been to scale back discussion on source credibility and pseudoscience (the point was made a bit often) and instead share more examples from a wider range of homeowner properties, such as mine with heavy clay soil and very intense sun and heat. I have two questions I hope Professor LCS will answer. I am trying to preserve the last patches of Mexican narrow leaf milkweed on my property for the threatened monarchs but need to control weeds before the city comes after me for code issues. Is my only choice to mulch around the milkweed I can see growing, and once done blooming leave empty spots where I am hoping it will come back next season? Also, I have these vine-like weeds which have extremely deep roots. They are actually scary smart weeds that will find the smallest amount of sunlight and poke up through a tiny opening. They root even under the mulch and vine until I have lots of weeds growing out and up right up next to the trunks of my trees. How do I stop weeds from growing up and around the trunks? I hope you see my newly delivered pile of chips!
Date published: 2019-09-12
Rated 3 out of 5 by from It’s ok. Just got on line to review this. Kind of disappointed with info as I wanted more on agriculture instead of just “gardening (Flowers & such). Also the streaming was slow & had to stop several times to chat here up. Not a lot of info I didn’t already know.
Date published: 2019-08-15
Rated 5 out of 5 by from Excellent Resource With Great Information I learned a lot and enjoyed this series completely. I highly recommend it!
Date published: 2019-08-07
Rated 2 out of 5 by from Change in Packaging is A Deal Breaker While the course itself is up to the usual standards- high and worth five stars, and readers of this review should consider it as such- The 'bright' idea of stacking five disks on a single spindle leaving me to juggle to attempt to get the next one and keep them in order is unnecessary cheapness and needs to be called out. 'You' 'fixed' something that wasn't broken and thus broke it.
Date published: 2019-06-28
Rated 5 out of 5 by from The Science of Gardening This is not a course for people hoping to learn how to garden. However, having many years maintaining several garden types, this course does a wonderful job of teaching the SCIENCE of gardening. Professor is easy to understand and presents herself in a very professional manner.
Date published: 2019-06-28
Rated 5 out of 5 by from I learned a lot. The class focuses on shrubs and trees and landscape plants. I learned many of the practices I have been using for years have no scientific basis and in fact are harmful. I very much liked the scientific/academic approach of the material. The instructor was very good.
Date published: 2019-06-19
Rated 5 out of 5 by from Well done course Very useful in practalilty and depth of knowledge . Great content well presented
Date published: 2019-05-17
Rated 5 out of 5 by from Nicely done. Covers of lot of material very well and debunks a lot of myths. Informative and enjoyable.
Date published: 2019-05-16
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