You wouldn't think water could make plants burn, but according to some gardeners, it can.
Jim Hole has heard a lot of gardening myths in his time at Hole's Greenhouses & Gardens, and the old water-droplet-burning tale is one of them. The story goes that you shouldn't water your plants in the middle of the day because the droplets will act as magnifying glasses and scorch rings on the leafs.
It's totally false, says Hole — if it were true, we'd have spotting like measles all over town after every thunderstorm. Yet the myth's so pervasive that he's even seen it turn up in Discover — a respected science magazine. "It's amazing how that whole myth has a life of its own."
Science, gardens, mom
Hole, a certified arborist with a plant science degree and co-owner of Hole's, will be giving a talk this Mother's Day at the Telus World of Science in Edmonton.
Moms and kids are the biggest fans of the science centre, says spokesperson Dan Vankeeken, so staff have arranged a whole day of activities for them. Kids can decorate a pot and plant a flower, build a Lego garden, and get half-off the price of their mom's admission.
"It's a way for kids to give back to Mom," she said.
Hole will give his talk on gardening myths at about 1 p.m. in the centre's star theatre, Van Keeken continues, discussing the effects of rocks on drainage and other well-worn concepts. "All that is deeply rooted in science, pun intended."
Scientists have long been interested in plants, says Frank Florian, director of public programs at the centre — Gregor Mendel pioneered the field of genetics by studying pea plants in the 1800s, for example. And there are plenty of mothers who have contributed to the field of science, such as Nobel Prize-winner Marie Curie and astronaut Julie Payette.
Former lieutenant-governor Lois Hole was a scientist in the garden, says Jim, her son.
"She kind of understood science from the practical side," he says. She knew to dig up soil around roots to expose cutworms to birds, for example, and to keep mature plants cool so they'd branch properly. "What I learned in school confirmed much of what she had done."
Knowing the science of plants can help make you a better gardener, Hole says. "I can't afford myths in the greenhouse," he says, which is why he makes sure to research as much as possible. "You have to look at what is the truth about it."
Myth-busting
Take the water-droplet myth, for example, Florian says. While a drop on a leaf can act as a magnifying glass by focusing light rays, it won't burn the leaf since those rays are focused at a point beyond the surface of the leaf. Even if you had some sort of transparent leaf, the light would have to hit the drop at just the right angle to cause any harm.
Rings on leaves are caused by disease or cold shock, Hole says. It's generally not a good idea to water when the sun is out since the water will evaporate, but you can use that evaporation to keep strawberries cool.
Many gardeners think they'll get better roots and flowers with phosphorous, Hole says, which has led to overuse. "It does not trigger flowering, and it does not increase rooting. It's a waste of a resource and can also lead to more algae problems in lakes and rivers."
Rooting and flowering are controlled by many factors, he explains, including light, day length, and other nutrients besides phosphorous. "If people over-apply this stuff, they're doing more harm than good."
Plants don't care about philosophy or feelings, Hole says, but they do care about science. "If conditions are right to grow, they're going to grow properly."
Call the science centre at 780-451-3344 for more on Hole's talk.
