Gardening columns prove thorny with Star readers

As the Star’s public editor, I respond to complaints from readers who have issues with stories we’ve published.

Those stories might deal with weighty matters — foreign affairs, investigations, politics, health care, or law and order.

And, as I’m learning, they can also pertain to lighter topics like gardening.

Still a bit fresh in my position after having spent years writing about hard news, I’ve been somewhat surprised to see how serious our readers can get when they disagree with advice that gardening experts Mark and Ben Cullen provide in their weekend column.

Mark Cullen has written a popular Saturday column for 12 years, five with his son Ben and seven by himself before that.

Largely targeted at the home gardener, the column has tips on everything: spreading compost and sand to grow shade-loving plants; advice about how to shear a spruce, juniper, fir, cedar or pine so they fill out more in the fall.

You want to grow fragrant lavenders in your Toronto garden? Try a hybrid — they’re hardier, the Cullens say.

The father-son team get a lot of appreciative responses from Star readers.

“I enjoy the job very much. We give a lot of thought to our column,” Mark Cullen, 66, told me in a recent interview.

But there are also those readers who can get, shall we say, prickly.

That happened recently, when the Cullens wrote a column recommending that gardeners plant thorny shrubs and trees that can act as “guard dogs” to discourage creatures like mice and raccoons.

The pair wrote that black locust trees (Robinia pseudoacacia) — which have short, sharp spines on their branches — and thorny Japanese barberry shrubs (Berberis thunbergii) are useful for growing in order to keep pests away.

But that advice didn’t sit well with everyone. For example, reader Laura pointed out in a letter to the Star that both are invasive species in Ontario.

The Cullens “should know better than to recommend this,” she said in her letter.

She pointed to a report by the non-profit Ontario Invasive Plant Council that says the black locust trees out-compete native plants, forming dense colonies that “shade out” those plants.

She referenced a similar study on the Japanese barberry, and added that organizations like Master Gardeners of Ontario — a non-profit that helps home gardeners — is “working hard to encourage people not to plant this species” in their gardens.

“I wish [the Cullens] would not use this platform to confuse readers,” she said.

Ouch.

In reply, Ben Cullen told the Star that “the Japanese barberry is an old nursery stalwart that was not always considered invasive, though that has changed.”

The black locust is also now considered invasive since naturalizing in Ontario, he added.

So, we revised that column to reflect these details.

A reader complaint about another recent column wasn’t as straightforward to resolve, however.

A librarian from outside the GTA took issue with advice the Cullens provided on pruning trees, including “cutting back” oaks in the summer.

“The first recommendation from the authors regarding oak is a serious mistake,” the librarian wrote my office to say.

Oak wilt is a fatal disease that spreads readily; one of the ways to avoid it is by not pruning or injuring oaks during their active growth season of March/April to October, she argued, pointing to findings in a report from Iowa State University’s department of horticulture.

Mark Cullen told me the study referenced by the reader is from the American Midwest and is therefore likely not relevant to Ontario.

“Oak wilt is not something I’m familiar with … I’m not suggesting I know everything about oaks. I’m suggesting if it were a prevalent problem in Ontario, I would probably be aware of its existence. But I’m not.”

Mark knows his stuff and I would defer to his wisdom on this point. He owns a tree farm in Ottawa and has grown over 2,000 oaks — red, white and pin oak. (He and his family previously owned Cullen Gardens and Miniature Village, a show garden in Whitby, as well as a growing farm in Brooklin, Ont. and a chain of retail garden centres called Weall and Cullen Nurseries.)

He went on to say there aren’t always precise answers when it comes to gardening.

“The business of gardening is the business of nature. And when we deal with nature, it’s not always black and white. We deal in grey areas.”

Mark says the world is a serious place that seems to be getting “more serious by the day,” and gardening is an opportunity to “just lighten it up a little bit and have some fun.”

Words to live by, whenever we stop to smell the roses.

Donovan Vincent is the Star’s Public Editor and based in Toronto. Reach him by email at publiced@thestar.ca or follow him on Twitter: @donovanvincent