On February2, 2013 Nathan and I attended a planning meeting for the Deep Winter Producers Association. This was the first meeting of a small group of people growing or interested in growing produce in the winter. It was a chance to share ideas and create a supportive network of like-minded people. Go here to read Chuck's comments on the meeting. While we were there we met a gentleman named Bob who is interested in building a greenhouse. He talked about incorporating hydroponic growing in the greenhouse that he is planning. He has a background and working knowledge in home heating and the duct work that carries warm air in a house.
We shared with the group our attempts to keep our growing space warm without supplemental heat. We had plants that germinated on the heat mats but they did not grow. Our growing space would warm up nicely on sunny days but cool too much overnight. Our water containers were not up to the task of keeping the space warm overnight and by morning it would be cold.
On the first of the year it became obvious that what we were doing was not enough and we started using a milk house heater to add warmth overnight. This was sufficient to keep the greenhouse near or above freezing on all but the coldest nights. In our discussions with the group we learned that they were keeping their growing spaces at or above 40 degrees. Bob had an idea that we could enclose our water containers and then capture the warmest air at the ceiling and circulate it around the enclosed water containers. At the close of the meeting Bob followed us home and visited with us about his suggestions. He has graciously agreed to correspond via email and answer some of our questions as we go forth with implementing his suggestions.
This was three weeks ago and we have since had another couple days of really cold weather. We did add a second heater and that kept the water thawed in the containers. Some of the plants are starting to appreciate the longer days and higher angle of the sun and are perking up and starting to grow. I am cautiously optimistic that we can make this work.