One of the charming things about gardening is the way home gardeners share information, often passing down tips and tricks that are decades old.
Just one problem: Many of them are wrong.
“A lot of these old-fashioned things are handed down from generation to generation,” says Robert Pavlis, an Ontario-based Master Gardener, blogger, educator and the author of several books, including two volumes of Garden Myths.
Just because you’ve always done something a certain way, doesn’t mean it’s actually what’s making a difference, he says.
There are so many variables in gardening, it’s hard to know if something really works without serious research and scientific methods.
Sometimes there’s a kernel of truth in old-time gardening practices. Marigolds supposedly ward off root-knot nematodes — microscopic pests that damage roots — from tomato plants, says Glen Bupp, a commercial horticulture educator with Penn State Extension in Pittsburgh. And there are certain varieties of marigolds that do have some efficacy against nematodes when the green plants are turned into the soil before tomatoes are planted, Bupp says.
“However, when they’re just alive, living as a normal plant in between plants, those compounds … aren’t being released into the soil,” he says. “So, it’s not doing its thing.”
So why do these customs persist?
Garden advice becomes twisted like a game of telephone, garden books go out of date and, of course, the internet and social media, while often helpful, can also contain misinformation. Online garden forums or sites sometimes spread pseudoscience or sell products in the guise of advice, experts say. One good way to truth-test gardening information: Check with your local extension service, an educational partnership between land-grant colleges (such as state universities) and the U.S. Department of Agriculture, or search on websites with .edu addresses that are affiliated with educational institutions.
“I think maybe 20, 30, 40 years ago, a lot of the university research was more focused on agriculture than on home gardening,” says C.L. Fornari, a Cape Cod-based gardener, lecturer, radio host and author of Coffee for Roses: ... and 70 Other Misleading Myths About Backyard Gardening. “With the knowledge that what home gardeners do in their yards and gardens makes a difference to our environment, there’s more research being done and also more publicizing of that research.”