One Greenhouse, Many Winter Greens
Written onMarch 01 , 2008
In the depths of winter, a visit to Carol Stedman’s new greenhouse in Hartland provides a breath of spring. A sea of tiny greens waves hello. Claim a seat on the cement blocks that ring the 2-ft. high garden beds, bend over, and take a whiff of soil and fresh growing things. This is what I did on a recent January day. With snow blanketing the out-of-doors, the air temperature inside was only slightly higher than outside, not really warm. But the soil… a thermometer stuck deep in the dirt read a balmy 60 degrees. What was going on?
Carol’s greenhouse is not the ordinary structure you find in the backyards of most home gardeners. It is unique because, in her effort to grow food year-round, Carol has installed an innovative soil-heating system and moving track lighting that you don’t often see in small-scale greenhouses. Plus, she is on her way to eliminating the use of fossil fuels to power her greenhouse–an important goal in this age of skyrocketing energy prices.
On a day with a mix of clouds and sun, I stopped by Carol’s house on Clay Hill Road to find out more about her greenhouse. Jeem Peterson, the builder, was happy to answer my questions. (Carol was out running errands; I would catch up with her later.) Construction had started last fall, and was not quite complete at the point that I visited. But did that stop Carol from planting? No way! She wanted to provide the Upper Valley Food Co-op in White River Junction with fresh herbs and spicy greens.
Making the best of a location on the northwest side of a hill, the 16-ft. x 24-ft. greenhouse is very well-insulated. But Carol realized that soil temperature is much more important for the growth of hardy greens in winter than air temperature, so she and Jeem designed a system much like radiant floor heating (in which tubes of warm water are placed beneath the floor of a house to warm the rooms). Call it “radiant dirt heating.” Tubes of warm water are spread out under the beds. These tubes are connected to a 500-gallon, 4-ft. deep water culvert in the middle of the greenhouse, which provides a heat sink. Pipes carry the water up to the peak of the greenhouse to be heated by four black-fabric swimming pool heaters that capture the warmth of the sun (when it’s out). In the depths of winter, when the sun hides behind the hill for the months of December and January, the water is heated by a cattle water heater (which will soon be replaced by a more efficient in-line one).
In addition, two grow lights hang from a track above the veggies to help make up for a deficit of winter sun. Powered by electricity, they glide slowly back and forth in the early and late hours, extending the day and fooling those little plants. Jeem showed me the electric box with a thermostat, and boxes that said things like “vent fan” and “heat tank.” Above, on the north wall, he pointed out the “windoors”–used doors from The Cover Store, a local salvage shop, turned sideways and turned into windows for summer ventilation.
Jeem was obviously a man in his element. In response to my query about why he builds greenhouses like this, he said, “I do this to lower the number of petro calories to grow food. We need to feed ourselves, and stop paying people from far away to grow it for us. Let’s pay our farmers!” A worthy sentiment.
So, back to Carol, who has worked in the natural foods industry for over 25 years as a natural foods store owner, sales rep, and wellness educator. Some of her greens she eats, and some she sells to the Upper Valley Food Co-op. Yes! Spicy greens are delivered, by Toyota Prius, from Carol to Co-op. Carol says she’s a novice, keeps a gardening notebook, and is always learning. She’s having fun eating her way through this experiment!
What got Carol started? About four years ago, she noticed that a couple of expensive local restaurants were serving old mesclun shipped all the way from California. Her response was, “We can do better than that!” Up went the hoop house, which extended the growing season some, and many winters were spent reading about growing food year-round–books by the likes of Eliot Coleman and Shep Ogden. But she started dreaming of a sustainable greenhouse that would go further than Eliot’s techniques. Hmmm... A wood-fired greenhouse? Who would tend the fire if she were gone for a few days? And given the site orientation, some kind of back-up would probably be necessary. Carol duly noted the sun pattern for a couple of years. With the goal of someday weaning herself from fossil fuel, but willing to initially use minimal amounts, she enlisted Jeem to help create the structure that now sits just across the driveway from her home.
“I’m a nutcase when it comes to my passion for year-round growing,” Carol says. “I get as excited about winter growing as an athlete about his favorite sport. When it comes to producing fresh food here in the winter, people tend to roll over and give up. But we can do more! In addition to some large operations like Pete’s Greens (in Craftsbury), we can find ways for homes, small market gardens, to feed ourselves and our neighbors while supplementing income. Some survivalists say the sky is falling. Au contraire! I am running towards a local food system that is rich in variety, abundant and delicious.”
With any luck, we’ll be seeing much more of Carol’s bounty on the produce shelves at the Upper Valley Food Co-op.
Photo of Carol’s greenhouse by Sharon Mueller