Canada: Why butterflies, bright flowers and vibrant dyes are taking over this downtown Toronto rooftop farm

Sectioned off from rooftop tomatoes and cabbages, TMU’s natural dye and fibre garden is filled with plants that were once among the most coveted and useful in the world.

By Marco Chown
The Star
Oct. 12, 2025

Excerpt:

High above the urban clatter of jackhammers, sirens, and car horns, a Monarch butterfly flits between the bright yellow and orange blossoms of an African Marigold and the tiny fuchsia flowers of a Japanese Indigo.

The rooftop farm at Toronto Metropolitan University is a hive of activity this time of year, with insects pollinating plants, staff harvesting produce and students carting bales of hay to cover the soil before winter.

While community members have benefitted from the vegetables that have been grown here for more than a decade, the Urban Farm on the roof of the George Vari Engineering and Computing Building on Church Street has now expanded its offerings to include plants cultivated not for nutrition but for fashion.

“Everyone’s heard about sustainable food, but no one thinks about sustainable clothes,” said Jess Russell, operations coordinator at one of two rooftop farms at TMU. “This project has sparked a ripple effect across the farm. We’re now doing so much more than just growing food.”

Sectioned off from the tomatoes and cabbages, the natural dye and fibre garden is filled with plants that were once among the most coveted and useful in the world, but have become neglected as industrial processes transformed the textile industry with plastic fabrics and synthetic colours.

Swaying in the breeze, the deep purple “pin cushion” flowers of the Black Knight Scabiosa contrast with the yellow flowers of the Golden Marguerite that grow a few meters away. The unassuming green tufts of the Murasaki plant grow underneath the towering stalks of the Black Hollyhock. The flowers, leaves and roots of these plants will be harvested to tint dye baths red, yellow, purple and blue for fashion students to create their own hues.

Thanks to North America’s first green roof bylaw, passed in 2009, Toronto has become a world leader in living architecture. There are now more than 1,200 green roofs installed across the city, totalling more than one million square meters in area (the equivalent of more than 122 CFL football fields, according to City Hall). Many of these roofs are covered with simple grasses and a layer of dirt that absorbs rainwater, limiting runoff while insulating the building and reducing heating and cooling bills. More elaborate green roofs, like TMU’s rooftop farm, are few and far between, but reveal how a bit of extra effort can produce compounding benefits.

“We have such an advantage growing on the rooftop,” said Russell. “Ground level gardens have to deal with so many pests, like raccoons and mice that can’t get up here.”

Perhaps the most impressive part about rooftop farming is that the microclimates it creates have allowed plants from Asia, the Caribbean and the Mediterranean, which don’t normally grow in Toronto, to thrive.

This has drawn visitors who can’t believe there’s a local Japanese Indigo plant in the city core, said Russell.

“It’s the most sought-after plant in the dying world,” she said. “People go crazy for it.”

A couple of blocks away, Rachel MacHenry dips a swatch of fabric into a steel pot filled with a very unappetizing brew. The brownish-yellow liquid doesn’t look like it would make a very attractive piece of clothing, either.

But when MacHenry, an assistant professor of fashion sustainability at TMU, pulls the cloth out of the Indigo dye bath and begins squeezing out the liquid with her fingers, it starts changing colour and transforms into a bright blue before her very eyes.

“There’s a revival of interest in these natural dye processes going on all over the world,” she said, propelled not only by a desire to reduce the gargantuan amount of waste produced by the fast fashion industry, but also by a new generation looking for climate solutions in traditional knowledge and methods.

Unlike synthetic dyes, which are often carcinogenic and have been found dumped into natural waterways untreated all over the developing world, natural dyes are beneficial to the environment, said MacHenry, who adds her used dyes to the compost used to fertilize the rooftop farm.

“Many of the students I work with are desperately looking for ways to maintain their ethical outlook in life and work in fashion,” she said. “There’s a lot of looking back to move forward.”

Flax gets spun in the classroom of Rachel MacHenry, Assistant Professor of Fashion Sustainability, Decolonization and Design.

It’s not only natural dyes that are making a comeback at TMU. The rooftop farm is also growing flax, which the students then transform into linen.

One of the oldest crops in the world, flax has been spun into long threads and then woven into fabric for thousands of years. More recently, flax has been grown for oils used in paints, and the vast majority of flax continues to be grown for industrial processes. In fact, TMU had to source its particular strain of flax for linen production from the Netherlands, as it wasn’t available in Canada.

Using hand tools produced by design students in the woodshop, the flax is scythed down and bundled to dry in the sun. It’s then “broken” and “knocked” to separate the husk from the fibres, before it’s combed to produce long, sand-coloured strands that look a lot like human hair.

“This is the ‘flaxen hair’ you read about in all the fairy tales,” said MacHenry. “We’re using some of the oldest techniques known to humankind.”

Sitting at a spinning wheel, fifth-year fashion design student Emma Piercey looks like she is straight out of a Renaissance oil painting. Pushing a pedal with her foot, she twists blond flax filaments into a sturdy linen thread.

“I have always tried to do my own natural dying,” she said, using random food scraps to make colour. “But Rachel opened my eyes to traditional practices and what’s possible.”

From the rooftop farm to the clotheshanger, TMU is not only ensuring old knowledge doesn’t die, it’s redefining just how local fashion can be.

“It would be possible to have a fully local system of fibre, fabric and colour here in Ontario,” said MacHenry. “We’re doing it, on a small scale, right here every day.”

Read the complete article here.

Source: https://cityfarmer.info/canada-why-butterflies-bright-flowers-and-vibrant-dyes-are-taking-over-this-downtown-toronto-rooftop-farm/