Ontario Mushroom Farm

Ontario Mushroom Farm: A Durham Region Operation With Deep Industry Roots

At 9760 Heron Road in Ashburn, Ontario, mushroom production has been a way of life since 1978. Ontario Mushroom Farm operates from a site in Durham Region that sits at the center of one of Canada's most significant mushroom growing clusters, a stretch of countryside east of Toronto where the conditions and the expertise have aligned to support commercial-scale cultivation for decades.

The Ashburn Growing Cluster

Ashburn is a small community within the Municipality of Clarington, positioned along the rural roads that connect Oshawa to the north. It is not a place that draws attention, which is precisely what makes it suitable for mushroom farming. The land is affordable relative to the GTA, the agricultural zoning is stable, and the proximity to Toronto's wholesale markets means product can move from farm to distributor in under two hours.

The Heron Road address is shared with Greenwood Mushroom Farm, a fully integrated producer that operates alongside its subsidiary Windmill Farms Inc. Together, these entities represent one of the larger mushroom production and distribution operations in Ontario, employing over 300 people and supplying product across the province and beyond. Ontario Mushroom Farm is part of this broader ecosystem, handling composting operations that feed the growing rooms where the actual mushrooms are produced.

How Integrated Production Works

Modern commercial mushroom farming is not a single-step process. It begins with composting, a technically demanding operation that transforms raw agricultural materials like straw, chicken manure, and gypsum into the specialized growing medium that mushrooms need. The composting phase alone takes several weeks and requires precise management of temperature, moisture, and microbial activity. Get it wrong, and the growing rooms will underperform regardless of how well they are managed.

Ontario Mushroom Farm's role in the composting side of the operation is foundational. Without high-quality compost produced at scale, the growing rooms cannot maintain the consistent yields that commercial buyers demand. It is unglamorous work compared to the harvest and packaging stages, but it is arguably the most important part of the entire production chain.

Scale and Industry Position

The broader operation at this Ashburn site has grown through strategic acquisition. In February 2023, the group acquired Ostrom Mushroom Farms, a well-known Washington State producer, expanding its footprint into the American market. That kind of cross-border growth is unusual for a Canadian mushroom farm and reflects the ambition and capital backing of Instar Asset Management, the Toronto-based private equity firm that controls Windmill Farms.

For the local Ashburn community, the scale of employment at the mushroom complex is significant. Over 300 jobs in a rural Ontario community is a substantial economic anchor, and it helps explain why mushroom farming has remained viable in this area even as other forms of agriculture have consolidated or disappeared.

Product Range and Market Reach

The 4.5-star rating across 10 reviews reflects the experience of people who have interacted with this operation at the retail or wholesale level. The product range from the Ashburn complex covers the full spectrum of commercial mushroom varieties, from white button and cremini to portobello and beyond, meeting the needs of grocery chains, food service companies, and independent retailers across Ontario.

Durham Region's agricultural identity has shifted over the years as suburban development has expanded east from Toronto. But operations like Ontario Mushroom Farm demonstrate that serious food production still happens here, at a scale that matters to the provincial food supply chain. Mushroom cultivation, with its indoor growing model and relatively small land footprint, may be uniquely positioned to survive the urbanization pressures that are reshaping agriculture across the Greater Golden Horseshoe.

You'll find Ontario Mushroom Farm at 9760 Heron Rd in Ashburn, Ontario.