Whether you see it as profound social commentary or an irritating eyesore, the environmental costs of graffiti are impossible to deny. Toxic chemicals and noxious fumes go hand in hand with aerosol spraying, while graffiti removal techniques can be far more damaging than their original target.

But a new wave of environmentally friendly graffiti art has sprouted up on the streets of dozens of urban centres. Using moss as their medium, these living, breathing designs reclaim dead spaces and tear down the divisions between urban and natural landscapes.

Toronto-based social enterprise Sprout Guerrilla is now the latest addition to this movement. Founded by recent OCAD grad Julie Forand, Sprout Guerrilla is aiming to decorate Toronto's urban landscape with moss hearts as part of its new "I love my city" guerrilla gardening campaign. I spoke with Julie about the benefits of green graffiti, whether or not the whole operation is legal, and just how Mr. Ford would feel about the campaign.

"I was looking for a natural solution to the pollution problem in city streets and moss art jumped out at me," explains Julie. "It's a fun and creative medium that benefits the environment instead of harming it. And the moss graffiti kit and the 'I love my city' campaign just evolved from there."

The kits in question are DIY packages containing all the required ingredients for moss graffiti art. Users can choose to join the campaign and stick with the included heart stencil, or branch out and create their own unique design. Since moss thrives in moist seasons, the best time to "plant" is during Fall or Spring, and each design will require consistent watering before it starts to flourish. Toronto has a pretty extreme climate, with large variations in temperature, but moss can naturally handle harsh weather conditions. If the winter gets too rough, the moss will simply stop growing and become dormant until the better weather returns.

Of course, not every wall should be considered a canvas. When I press Julie as to the legality of guerrilla gardening, she dances around the issue. "Some people see graffiti as an art form that adds to the culture of a Toronto, and others see it as a form of vandalism that damages property. Moss graffiti adds a creative layer to the city, but it's also gentle on surfaces and easily removed. I'd say, be respectful and have fun with it."

But even if Toronto embraces the moss art movement, there's still the issue of our famously anti-graffiti mayor. It's hard to imagine Rob Ford approving of the campaign, even if it does eschew the usual aerosol cans. Julie, however, is undeterred. "If Rod Ford wants clean streets, this is a good way to go. The campaign is civic minded with the intent to beautify the streets and make them healthier...Rob Ford should get on board!"

Sprout Guerilla kits are available for pre-order on Indiegogo until November 4th.