“IAF funding helped Carmenia Farm mitigate the risk of investing in a developing, but not yet proven, technology that makes year round farming possible without burning fossil fuels or connecting to a grid.” Becky Mason, Carmenia Farm

Freezing night-time temperatures cause havoc for small-scale greenhouse growers like Becky Mason at Carmenia Farm in North Cowichan.

Not many small greenhouses run during winter in cold climates because heating is expensive. Most farmers view their greenhouses as season extenders. Becky thinks this is a missed opportunity.

“Farmers aren’t getting the most out of their greenhouse investment,” says Becky. “The farmers’ market in Duncan runs year round, but often all you see in January are root crops. Fresh greens could really clean up.”

Becky wanted to explore a type of passive heat storage that uses salt, so she approached IAF to fund a pilot project. The salt, known as eutectic salt or hydrated
salt, absorbs heat during the day and releases it at night to keep plants warm. 

“When you look at the rapid pace of climate change, we need a paradigm shift away from our reliance on fossil fuels,” adds Becky, who also teaches economics at Camosun College in Victoria. “Turning salt into thermal storage is a great idea, but it has to make sense from a cost/benefit perspective.”

Becky had tried growing lemons inside her 200 square foot greenhouse, but dangerous cold snaps are not conducive to citrus plants even with lights to keep them warm.

She kept detailed temperature records inside and outside the greenhouse for one winter using electricity and again last winter after the hydro had been replaced
with the salt bottles.

It took a bit of trial and error to get everything working right, but results indicated gains on both inside temperatures and soil temperatures. Overnight temperatures inside never dropped all the way to freezing even at -4C outside, and the salt provided average gains of three to four degrees Celsius. The lemons were happy and so was Becky.

“With a 10C soil temp and an interior temp above freezing, small farmers will be able to grow and market greens and other cool weather vegetables throughout winter,” she notes, adding that she’s decided to try winter greens herself.

It’s promising news for small farmers and First Nations in off-grid locations.

For more project results and a video, visit: www.carmeniafarm.ca.

FUNDING: $2,133 provided by Agriculture and Agri-food Canada and the BC Ministry of Agriculture through the Canada-BC Agri-Innovation Program under Growing Forward 2, a Federal-Provincial-Territorial Initiative (INN135SP).