Expert gardeners share their memorable gardening mistakes and happy accidents

We’ve all heard people say: “I don’t have a green thumb. I kill everything,” as if gardening is an inherited talent.

The truth is no one is born a great gardener. It takes years of practice – and countless failures – to get a handle on the mysterious world of plants. And even then, the most seasoned pros still make their fair share of blunders. Regardless of how many books you read or gardening courses you take, the best way to learn is through trial and error. As U.K. gardening coach Janet Kilburn Phillips famously said, “There are no gardening mistakes, only experiments.”

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The Globe asked five Canadian gardening experts to share examples of some memorable missteps and the lessons they learned, as well as happy accidents that occurred because they weren’t afraid to “experiment” and see what would happen next.

Carlos Moniz

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Director of horticulture at the Butchart Gardens in Brentwood Bay, B.C.

The mistake

Our roadway leaving the gardens has been lined with an impressive stand of Hawthorn trees for as long as I can remember. They were always lightly pruned each year, basically removing sucker growth, and provided a beautiful spring display. Years ago, a respected tree expert advised us to let these trees grow out to create a tunnel-like effect for our visitors. Not surprisingly, the sucker growth exploded. Instead of creating the beautiful canopy we had envisioned, the trees simply kept reaching for the sky. Ultimately, they lost their true form and looked terrible.

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This growth became a maintenance and pruning nightmare. Sadly, the trees became weaker, and disease and decay took hold. We have had to replace many of these magnificent trees. What we learned is if you choose to manipulate a tree’s form, you must be prepared to commit to it for its life.

The happy accident

In recent years, we have modified our plant-production methods and one of our nurseries became redundant. We had been planting cover crops for years, but this was never very attractive, and the two-acre field is the foreground to our summer firework display. We considered seeding it with turf grass, but wanted less maintenance, so we seeded it with a pollinator mix, including California poppies, which our owner loves. This once-underappreciated growing field now provides a gorgeous mass of colour throughout the season and has become the talk of the gardens. Plus, it is a wonderful habitat for our pollinators.

Kat Granger

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Master gardener and founder of Seeds of Imbolc, cultivator and seller of heirloom organic seeds and plants in Fergus, Ont.

The mistake

I adore weeping purple beech trees. Their dancing bronze leaves are like witnessing nature’s ballet. A few years ago I saw one on sale, and bought it, even though I had no place for it. I planted it in my dream spot at the front of my house, giving me privacy from the street, and I could see it from my kitchen window. Over the years, birds have nested, and I love to watch them come and go. However, the problem with my “dream spot” is that it’s directly under hydro lines and the tree’s branches are in a constant battle with the wires. It’s a never-ending challenge to keep my beautiful weeping purple beech away from hydro crew’s chainsaws. This experience has reminded me of the wise gardener’s adage: Right plant. Right place.

The happy accident

Encouraged to try growing dahlias, I stuck my toe in with a few varieties. Fast forward a few years and many “learning opportunities” – never failures – later, I now grow over 150 varieties, offering them Canada-wide. I have become totally addicted to these magnificent blooms, which come in an incredible array of colours and forms, and I now hybridize my own dahlia varieties. Waiting to see them move from seed to a never-seen-before bloom is stuff that gets me out into the garden with the excitement of a young child at Christmas.

Cathy Kavassalis

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Conservationist and master gardener based in Oakville, Ont.

The mistake

I am a passionate plant collector who had a vision of transforming my garden into a botanical oasis. I amassed over 500 different plant species, each more exotic and unique than the last. My small garden was the envy of my neighbourhood – until it wasn’t. Amidst my treasured collection were invasive plants and they invited themselves into every nook and cranny of our street. I watched, dismayed, as giant butterbur, honeysuckle, lily of the valley, periwinkle and scilla commandeered the local natural areas. They were like those party guests who just don’t know how to call it a night, muscling out the native trilliums that once gracefully adorned the landscape.

I embraced a newfound respect for native perennials and devised a containment strategy for the non-natives. It also led me to co-found the Canadian Coalition for Invasive Plant Regulation, aiming to guide other gardeners away from similar misadventures.

The happy accident

I like to experiment and let things happen, which led me to try pairing the northern maidenhair fern, with its delicate, fan-like fronds, and the enigmatic blue cohosh. In spring, the fern’s burgundy fiddleheads couple with the cohosh’s dark purple shoots, creating a vision of elegance and mystery. As spring warms into summer, the maidenhair fern intertwines with the lacy leaves of the blue cohosh, becoming a symphony of textures and movement. By late summer, the two reach a crescendo with the appearance of cohosh’s fleshy blue seeds, which shine like gems in the shade. This unexpected combination was a stroke of luck, serving as a reminder that sometimes the most beautiful outcomes are not the result of meticulous planning, but from life’s unexpected turns.

Sean James

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Master gardener and owner of Sean James Consulting & Design in Milton, Ont.

The mistake

About five years ago, I planted Canada anemone in a little, shaded wildflower garden on my property. And it did very well – until it did too well, eventually taking over everything. As soon as I saw it getting out of control, I would remove it … then I’d remove some more … but there always seemed to be a little piece leftover that I’d miss, and it would start all over again. For such a pretty little plant it’s extremely pushy and far more than I bargained for.

I’ve learned that Canada anemone needs to be in a spot where it doesn’t need to be contained. At my new place, I planted it under some trees where grass won’t grow. It’s very happy there, and so am I.

The happy accident

I like to think I know my native plants, but I was recently introduced to a new one called bluet, which is so lovely and compact I bought it in three colours – white, pink and blue. I brought them home and stuck them in the ground. They were blooming a month later in June, and still blooming in November. Bluet is a gorgeous, hardy and versatile little ground cover that has brought me so much joy not only because of the length of time it blooms but also because it requires no maintenance. You don’t have to cut it down in the spring, and it’s excellent in pots, at the front of borders or to simply soften a pathway.

Jonas Spring

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Owner of Toronto landscape firm Ecoman, and founder of the Toronto Plant Market, a seller of locally grown native plants.

The mistake

Being a horticultural professional by day basically means I have 20 minutes on the weekend for my tiny back garden, which doesn’t get a spring cleanup, nor does it receive any kind of regular maintenance such as weeding. In other words, it’s the last place you want to drop an invasive species. I decided to explore using a native annual as a potential crossover plant that could appeal to all gardeners, so I planted evening primrose. I loved the name. It sounded so harmless. The reality is this bad boy grows up to six feet tall and produces thousands of viable seeds. It’s now in every nook and cranny of my property and beyond – from the tiny cracks between the asphalt on the driveway, to the eavestrough of my neighbour’s garage. Never assume that a plant with a sweet, benign name is innocent. Do your research.

The happy accident

I started putting plants – including native species such as harebell and hairy beardtongue, which typically grow on cliffs and alvars around Southern Ontario – into spots they wouldn’t normally grow. The result is I have created this beautiful living wall on the side of my house where insects love to chill out. I recently noticed that flying ants were having a sleepover party inside the bell-shaped flowers of the harebell. I consistently see them snoozing, napping and generally just “hanging out” in there. Just watching them brings me joy. I mean, can you think of anything better than having a snooze inside a flower? Me neither!

These interviews have been edited and condensed.