On a late January day in Eastport two residents were sitting in their lawn chairs, in shorts, with toes bared and digging into warm sand. Sally Erickson and her partner Timothy Bennett have built a year‑round greenhouse on their South Street property, and when the sun is shining more than just plants are enjoying the warm environment. Their 24' by 72' greenhouse is part of the Washington County Food and Fuel Alliance's (WCF&FA) greenhouse project, which is based on a project in the Blue Hill area.
In its third year with the greenhouse project, the alliance has set a goal to strengthen community and economic stability by increasing access to healthy local produce for individuals, food pantries and school children. It provides the tools for anyone to build a year‑round greenhouse with free building plans, workshop support and access to reduced cost supplies. In exchange for these benefits the alliance hopes that growers will donate 10% of their produce to a local food pantry.
Four years ago Tom Adamo and Tony Ferrara began the project in the Blue Hill area with a small grant and the goal to build a year‑round greenhouse at a local school. Just about 100 greenhouses later, the project has been embraced by educational institutions and individuals, with both Waldo County and Portland wanting to join Washington County in the effort.
The two men built innovations into the project that have helped with its success. They tinkered with greenhouse designs and the heating system and made the plans available, and a polycarbonate supplier agreed to sell the triple‑wall glazing and special fasteners at a reduced cost. The poly sells for about $40 below retail at $64.80 per 4' by 12' sheet and $86.40 per 4' by 16' sheet. Washington County's purchases for the program's two years have reached about $38,000, with about 30 greenhouses built so far.
Capturing heat for year‑round growing
The greenhouse design maximizes cold‑weather heat captured through a ductwork and reverse fan system. Buried under raised beds is a network of four‑inch corrugated pipes that then surface above ground and reach to the peak of the ceiling where the air is warmest during the day. Small fans push the air back down under the beds, thus warming the soil. The north wall and roof are built with rigid foam board insulation and no glazing.
Not everyone who has built a greenhouse has used the heat capture system, including Adamo, who has a 12' by 12' greenhouse. "That's enough for two, plus some to give away." His last tomato was harvested in December by creating a plastic enclosure within his greenhouse. Right now he and his wife are harvesting chard and lettuce. He also grows garlic, carrots and other cold‑tolerant plants at the outer edges of the greenhouse.
The University of Maine at Machias built a 16' by 20' year‑round greenhouse without a heating system in April 2011 and grew produce all summer. "We were chock‑a‑block with tomatoes," says Assistant Professor of Anthropology and Community Studies James Moreira. The decision not to incorporate the heating system was "in part to do experiments" on how it would work without and what could be grown successfully. Around the edges of the greenhouse the beds became too cold for what they were growing, but the beds in the middle were fine, he reports. In April they started tomatoes, peppers, kohlrabi and basic root crops such as carrots and beets. By the summer the tomato vines "were climbing through the vent window." For the fall and winter they have been growing lettuce and beets.
Another greenhouse without heat was built in Jonesport by Larry Finnegan. The 320-square-foot space has added considerably to his shoulder seasons. Broccoli, lettuce, cauliflower all grew well. "I was cutting broccoli into early December, tomatoes, too. We were over‑run with tomatoes. It was great! Although picking all those cherry tomatoes." He pauses. "Well, that wasn't great."
Erickson is a newcomer to the greenhouse community, with her planting season having just begun. The first lettuce batch was seeded the first of December and took six weeks to flush into growth because of the short days. Now one of her raised beds is a sea of bright green. Soon all 16 of the 4' by 8' beds will be planted as well as the 80' by 3' bed that wraps along the east and south walls. She is a big fan of the captured heat system. "It's unbelievably good," she says. Adamo says that he is researching a "second generation" heating system that stores heat underground using a sand sink.
On the three coldest nights of this winter the interior of Erickson's greenhouse fell below freezing. The first time she did not cover the plants with a protective fabric, and, while the plants froze, they survived because of their hardiness. The two other nights she used protection, and the plants were fine. She does plan on adding a wood stove. Because the large greenhouse will be producing for market, she cannot risk losing a greenhouse full of crops if a really cold spell hit for a prolonged period of time.
The Perry Elementary School greenhouse also uses the captured‑heat system. Teacher and greenhouse project manager Dan Morang says that the 16' by 16' building was producing year‑round with the help of about 20 students. After the holiday break in 2010, "the kids planted lettuce and spinach in January [2011] and harvested in March." The food kept coming with beds surrounding the greenhouse contributing more produce during the summer that the students sold through The Red Sleigh, providing valuable business skills to the students and bringing in enough sales to put money back into the project. UMM also surrounded its greenhouse with planting beds, and Erickson is planning to do the same.
Morang notes that last winter they covered their raised beds with mini‑hoop houses using flexible piping and plastic, but he says he's had no trouble with freezing. One bed along the south wall is not connected to the heating system, and he and the students are working on a different system for that bed using a variation of a hot‑water collection system. "The students have designed it. They'll research the placement, the AC/DC power choice, will make the PV panel and do data collection." He adds that the whole idea was student‑led, based on brainstorming conversations they had about projects and community. "The fifth and sixth grades wrote the grants." Well over 100 people from other communities have come to look at the project, even driving from as far as Bar Harbor. But even more exciting to Morang is that the students are taking what they're learning to their homes and building raised beds and planting. "They all love it," he says of their time in the greenhouse. And their work has paid off. Morang notes, "Last year we cut the produce bill in half [at the school]. I haven't checked yet for this year, but we've put in more, so I expect it will be higher."
Donations to food pantries have been starting. Finnegan donated tomatoes to his pantry, and the UMM greenhouse donated 100 pounds of tomatoes to the Machias food pantry. Erickson will be joined by two partners in the greenhouse market business, Emily Guirl and Micah Pascucci. While they haven't worked out the specifics, along with produce donation one idea kicking around is to provide vouchers to the pantry for people to come over. "Maybe there's a way to work with the pantry to learn about harvesting and growing," Erickson says. The gardens that will surround her greenhouse are also under discussion for a melding of community and market gardening.
Countering greenhouse ills
While the greenhouses have not been operating long enough to have encountered major problems, humidity is one, with builders noting that rot‑resistant wood is important to use for the framing. The heat air‑circulation system seems to help, with both Morang and Erickson reporting much less humidity than Adamo and Moreira. Aphids were a problem for some, but Adamo thinks that certain plants like eggplant attract aphids, and overcrowding plants can lead to infestations. Red ants visited the Perry greenhouse, but David and Sandy Perloff of the Perloff Foundation, who partially funded the project, offered up a solution they use in their own garden: coffee filters filled with cinnamon and clove. Now a vole has taken up residence, having wandered in when the door was left open.
Soil condition is another area of concern for greenhouses because the natural elements of rain, snow and wind are not present to soak and flush away problems. Photo‑sanitizing of the soil is one method that can be used, says Adamo. Erickson plans on using the super‑heating method for one‑half of her greenhouse at a time during a crop‑rotation lull. She'll encapsulate a section and let the heat build. Adamo explains that if the temperature reaches 150 degrees, it kills the bugs but does not harm earthworms that burrow down deep. The soil can also be rotated to outdoor beds, but as Morang says, "Lugging soil is the hardest part."
Some plants require special pollination, since even leaving doors open does not mean that pollinators will come in for a visit. Finnegan encountered that a bit in his greenhouse. "I'll need to be a bee myself and get down there with a q‑tip to pollinate" some of the crops like cucumbers and squash.
But the concerns are minor so far. Erickson looks across at the vibrant bed of green lettuce. "I'm surprised at how much fun this is."
More information about the greenhouse project is available through the WCF&CA website, <www.foodandfuel.org>. To see a greenhouse in action, visit the Perry Elementary School website, <perryelementary.org>, where a complete description of the project, including construction, is accompanied by photographs, videos of class garden projects and a greenhouse webcam.
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