Rooftop Garden – Sharing The Harvest

It may be difficult to imagine during the chilly winter season, but atop our building in Regent Park lies a rooftop garden that was full of beautiful, healthy vegetables only a few months ago.

How Much Did We Grow?

The rooftop garden – a result of a partnership between TAS and Cultivate Toronto – was developed with the intention to enable Cultivate Toronto volunteers to grow food for the Regent Park neighbourhood. I am pleased to report that the bounty far exceeded all of our expectations; over 385 lbs of food were harvested from the rooftop garden between the months of June and October. Among the harvest were a wide variety of crops, ranging from heat-loving tomatoes, peppers, eggplants, and melons, to squash, lettuces, hearty kale, and a variety of fragrant herbs.

What is the Value of the Produce?

Although it is interesting to know the weight of the harvest, it tells us very little about the economic value of the garden’s outputs had the vegetables been sold instead of donated. Consider the price per pound of basil compared to beets! A more useful metric is the estimated dollar value of the harvest. Based on the prices of vegetables sold at farmer’s markets and high-end grocery stores in the last year1, we have calculated that the value of the produce grown on the roof this year was $2,178. Not bad, considering that labor was confined to about 5 hours per week (mostly time spent watering – it was hot up there!)

Knowing the dollar value of the rooftop harvest is fascinating because it provides pertinent information to anyone considering an urban rooftop farming venture. In our case, the value of the harvest in 2013 is equivalent to 1/3 of the one-time start-up costs of the project (EarthBoxes2 , soil, hose bib installation). Calculation of the harvest value also supports the existing suite of social and environmental benefits already attributed to urban rooftop farming. It’s exciting to think that turning a small section of our roof into a garden can yield so much social, economic, and ecological benefit.

How Productive was the Garden?

Another relevant metric of the rooftop garden is pounds harvested per square foot. This measurement allows us to compare the productivity of our roof garden to other food gardens in the city. In our case, the Earthboxes represented 200 square feet; however, when the space between the planter boxes is included (necessary for airflow and the movement of people), the total square footage of the garden was closer to 570 square feet. With 385 lbs of harvest, this means the roof garden produced about 0.68 lbs per square foot.

385 pounds / 570 square feet = 0.68 pounds per square foot

Compared to the backyard gardens that Cultivate Toronto maintained in 2013, the rooftop proved to be very productive per square foot. In East York, Cultivate Toronto’s gardens produced about 0.3 lbs per square foot. This means that the roof garden produced more than twice as much food per square foot that the East York in-ground gardens3. There are likely several reasons for this difference, including the highly productive growing medium purchased for the Earthboxes, full day sun exposure, and intensive planting techniques that maximized the small space available. In addition, the water reservoir component of the Earthboxes helped to ensure the soil was never dry – which is challenging to avoid in in-ground gardens at the height of summer.

Where was the Food Donated?

Analysis of the rooftop garden harvest is not complete without considering that nearly all of the food was donated to a local community meal program run out of CRC at 40 Oaks – home of the CRC Community Food Centre. In the words of Liz Curran – CRC’s Community Food Centre Manager – “the meal program provides community members with access to high-quality food in a dignified setting that doesn’t compromise their self-worth”. The meal program serves upwards of 150 breakfasts and 250 lunches per day and although the rooftop garden donations are a small subset of the total volume of food used in the kitchen, the freshness of the food could not be beat. According to Liz, “the produce [Cultivate Toronto] donated made it that much easier for us to be able to offer healthier meals to our community members”.

We could not have been more pleased to have shared our roof with Cultivate Toronto and the meal program at CRC 40 Oaks. Spring had better arrive soon because we can’t wait to have the volunteers back on our roof, working their green thumbs, and engaging with the community in 2014!

Special thanks for assistance with this blog post from Diana Gonzales of MyMarket, and from Jacob Levy, TAS’s volunteer researcher.


1. Prices were calculated based on the average price of vegetables from four different sources: MyMarketFresh City FarmsOrganic Price Tracker, and Whole Foods Market.

2. TAS purchased the EarthBoxes at the manufacturer’s educational rate because the garden was used to train new gardeners as part of CTO’s internship program.

3. Blog author’s note: I was the garden coordinator for Cultivate Toronto’s East York gardens in 2013 and the pounds/square foot number is based on my own calculations from 2000 square feet of in-ground vegetable gardens.