When they started Threefold Farm in Pennsylvania, Tim Clymer and his wife decided to distinguish themselves by growing unusual crops like pawpaws and kiwi berries.

They also wanted to grow figs, but to do so, they needed to heat a greenhouse over the winter.

Clymer: “If we had to heat with propane, I don’t know that we could grow figs economically.”

So the Clymers installed what’s called a climate battery greenhouse. It makes use of the extra heat greenhouses create on sunny days. But instead of venting that heat, the system pumps it through tubes underground. The heat transfers to the soil.

Clymer: “We’re using the earth. You can think of it as a big thermal battery.”

When it’s cold, fans draw the heat stored in the earth back to the greenhouse to warm the figs.

Clymer: “We are harvesting our last figs about mid-December. So I was pleased.”

The Clymers are sharing their greenhouse designs with other farmers who want to extend their growing season without the environmental and financial costs of propane heat.

Clymer: “My wife and I feel like we’re called to be good stewards of what we’ve been given, and so if we can lessen our footprint, we feel like that’s the right thing to do for our farm.”

Reporting credit: Daisy Simmons/ChavoBart Digital Media.