Basic Gardening Myths Dispelled

Basic gardening advice is available everywhere you look, but not all of it is right. Learn more from the authors of Decoding Gardening Advice.

I’m always open to advice. And when it comes to gardening, I find that fellow gardeners are only too happy to help. But here’s where it gets tricky. Right when I’m in the middle of applying some of those good, home-tested garden secrets to my yard, a well-intentioned person with his or her own home-tested secrets stops by and tells me I’m doing it wrong. Ugh!

With so many garden myths floating around out there – and just as many helpful gardeners (myself included) passing them along – I was excited at the chance to bust some myths with Jeff Gillman and Meleah Maynard’s book, Decoding Gardening Advice: The Science Behind the 100 Most Common Recommendations. Jeff is an associate professor of horticulture at the University of Minnesota, and Meleah is a master gardener. Over the years, they’ve fielded hundreds of gardening questions and have come across a lot of contradictory opinions. In an effort to set the record straight, they offer some smart, research-based advice to answer the questions they hear most often.

What I love most about this book is that the authors tell you why something works or doesn’t, and then suggest a better way to handle a situation. Here are nine myths that really resonated with me, and you can find even more in the book. It’s much more efficient than trying to decipher the myths on your own—or waiting for advice from well-meaning passers-by.

Basic Gardening Myth: Don’t plant flowers under trees.
Basic Gardening Fact: Flower beds actually can help keep trees healthy. They are also more sustainable than grass in the long run because they require less water. Choose perennials to minimize soil disturbance, and choose the smallest plants possible for the same reason. Carefully work them into the soil that’s there, rather than adding dirt for planting.

Basic Gardening Myth: Ladybugs are the best predators to release in the garden.
Basic Gardening Fact: I never even realized people did this! Ladybugs feed on vegetable-eating insects like aphids and mites. The problem is, they’re predisposed to spread themselves out rather than congregate in a single spot. (Good news for your neighbors, not so helpful for you.) Jeff and Meleah recommend trying other predatory insects, such as the minute pirate bug (Orius species), the big-eyed bug (Geocoris species) and green lacewing larvae (Chrysoperla rufilabris). Buy from a reputable source (usually online) and release near the insects you’d like them to feed on.

Basic Gardening MythsBasic Gardening Myths Andris TkacenkoShutterstock
Andres Tkacenko / Shutterstock Basic Gardening Myth: Organic pesticides are good. In fact, even these can have dangers.

Basic Gardening Myth: Organic Pesticides are always better than synthetic.
Basic Gardening Fact: Jeff and Meleah fully support organic strategies for pest control, but warn against accepting a pesticide as perfectly safe simply because it’s organic. Copper sulfate and pyrethrum are both natural, but can be poisonous to people and the environment. When it comes to any pest control, start by identifying your enemy. Once you know the pest you’re fighting, you can choose the best strategy. Soft-bodied insects like mites, aphids and immature mealybugs can be treated with a spray of 1 to 2 tablespoons of dish soap added to 1 gallon of water.

Basic Gardening Myth: Full-sun plants grow only in full sun.
Basic Gardening Fact: Ask six gardeners to define full sun and you might get six different answers. Jeff and Meleah define it as at least six hours of unfiltered sun between 9 a.m. and 5 p.m., but recommend that gardeners experiment with inexpensive plants to see if they can push the boundaries. Meleah has had success planting “full-sun” flowers in spots that get less than three hours of direct sun, with filtered sun in the afternoon. Her plants are healthy, although they’re shorter and sport fewer blooms than a neighbor’s specimens that get much more light. And Meleah is just fine with that.

Basic Gardening Myth: Divided shrubs will always come back.
Basic Gardening Fact: I thought this, too, but it turns out these woody plants have woody root systems that aren’t as resilient as other perennials. If a divided shrub survives, it will never develop a natural-looking shape because of its limited ability to regenerate. Shrubs that produce offshoots, like lilacs or spireas, have better odds, but overall, the best way to propagate is from cuttings.

Basic Gardening Myth: Veggies must have full sun.
Basic Gardening Fact: This is just one of the myths I learned about veggies. (I also found it’s fine to plant vegetables in containers or in rows that aren’t straight.) Tomatoes, peppers, cucumbers, squash and eggplant need at least six hours of full sun. But more forgiving veggies can get by with less – in some cases, as little as two hours! If your garden is somewhat on the shady side, try growing beans, broccoli, carrots, cauliflower, coriander, leeks, onions, peas, radishes and rutabaga.

Basic Gardening MythsMcMac / Shutterstock
McMac / Shutterstock Ladybugs aren’t always all they’re cracked up to be. Lacewings might suit your garden better.

Basic Gardening Myth: Divide and transplant only in spring and autumn.
Basic Gardening Fact: Most perennials do best when divided in early spring, as new growth begins to emerge. And in spring and early autumn, you don’t have to fuss over them much. But experienced gardeners and professional landscapers move, divide and plant when the need strikes, be it spring, autumn or a summer day in between. Protect transplants from hot summer sun and heat by working in the early morning or evening, or on cloudy days. Water well, and if the plants seem stressed, provide light shade until they adjust. Stop transplanting about six weeks before the ground freezes, or you may lose plants to the cold.

Basic Gardening Myth: Plant trees deeply.
Basic Gardening Fact: Not the best idea, according to Jeff and Meleah. Although tree roots provide several functions, the roots that provide the most air, water and nutrients are just inches below the soil surface. Plant too deeply and it decreases a tree’s lifespan, forcing roots to struggle upward for oxygen. Position the root flare, where the main stem transitions to the roots, at or just above soil level.

Basic Gardening Myth: Change potting soil in containers every season.
Basic Gardening Fact: Jeff and Meleah agree with a growing consensus that discarding potting soil each year is probably overkill for most container plants. A valid and affordable alternative is to simply work in a little compost from year to year to improve the soil structure and provide added nutrients. But if you’re growing a rare or cherished plant you’d hate to lose to disease, it’s worth the investment to change the potting soil annually.