The Science of Gardening (2018 - 2018)

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.

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.

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?

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.

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.

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.”

“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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.