There are two kinds of gardeners in the Yukon: those who can grow tomatoes and those who can’t.

With Yukoner Bob Sharp’s Solar Growing Greenhouse Kit – a stable-temperature greenhouse that extends the growing season by three months – it is now much easier to join that first club.

“Nothing about this is secret,” Sharp says. “It’s physics… it’s a heat sink.

“A heat sink is a kind of body that will store heat when you want heat. And it releases the heat when you want to release the heat. Ours is a mix of rock sizes; a small rock will take a couple of hours to heat up and a rock the size of your fist will take seven or eight hours to heat up.

“But it will also take seven or eight hours to cool down and a small rock will cool down much more rapidly.”

That, that right there, that is how he has built a better greenhouse.

After swatting away the word “genius” in my question, he hangs his head and finally admits, “It is sort of my invention. The heat is from the sun and it passes through a glazed window. I take that heat and pass it over the rocks that are placed under the soil bed, which has a secondary effect: it warms the soil.”

And, so, you have a greenhouse that does not overheat because the rocks are taking the excess heat away in varying degrees based on their size.

“Overheating is as big a problem as frost,” Sharp says.

Sharp and his son, Andrew, have turned this into a business. With a grant and support from the Yukon Research Centre’s Cold Climate Innovation program, they built four prototypes. Through trial and error, they wrung out as much knowledge as possible about how the greenhouses work. They then donated the greenhouses to Elijah Smith, Golden Horn and Whitehorse Elementary Schools.

The greenhouse at Whitehorse Elementary can be seen from Fourth Avenue and is available for tours from Sharp.

Justin Lemphers and his wife, Brigitte Parker, volunteered to help build the prototype greenhouses at Yukonstruct.

“We spent the afternoon building their test model and gave feedback on improvements,” says Lemphers.

Lemphers and Parker bought one of the 30 that were sold in the spring – which is double the projections for the entire first year of production.

“Food security,” says Parker when asked why they wanted one of Sharp’s greenhouses. “I am from Ontario where we had fresh tomatoes and fresh corn and fresh everything and to come up here and get these rock-hard tomatoes was…”

She searches for a word.

“…challenging. We wanted to grow for taste, for canning and for food security.”

“And for a lack of pesticides and a lack of fertilizer,” Lemphers adds.

“Yes, for our health, for our wellbeing and to share,” Parker continues. “There is nothing like sharing fresh produce from your garden with neighbours and your friends and family.”

Parker first met Sharp when he helped teach a master gardener course. Parker falls into the category of gardener who can grow tomatoes. Now she wants to try onions and peppers.

“Hot peppers are my dream.”

The greenhouses are available for order at www.solargrowing.weebly.com. More in-depth information is available at www.yukongreenhouse.weebly.com.

To make construction easier for their clients, Sharp’s Cowley Creek Road property is full of pre-built greenhouse parts.