Sustainable Greenhouse

Growing tomatoes in a sustainable greenhouse in Maine

Images by: Ross Donihue

Michael Donihue & Susan MacKenzie’s Sustainable and Educational Greenhouse Garden

Michael and Susan are both educators committed to making the world a better place through teaching. In June of 2013, they purchased an 18′ Growing Dome. Their dream was to create a sustainable greenhouse that balances natural and man-made environments, be able to teach their students and clients about sustainable systems, all while growing food year-round in Maine.

Overhead shot of a sustainable greenhouse in Maine

Michael and Susan have ample gardening experience. They had been growing an outdoor garden for years and experimented with different hoop houses before deciding to purchase a Growing Dome Greenhouse. They found that the hoop house would just extend their season, while they could truly grow year-round in the Growing Dome. I couldn’t help but laugh when Michael told me that putting the dome together “was a blast.” He loves to tinker and solve problems so the DIY greenhouse assembly option was more of a fun project than a lengthy chore.

Solar Powered Greenhouse

climate battery for sustainable greenhouse
Undsersoil climate control and climate battery being installed in beds

Although our Growing Domes are designed with sustainability and off-grid living in mind, Michael and Susan went the extra mile by connecting more solar panels from their home and a climate battery. The climate battery supplements their undersoil climate control and allows them to store surplus heat produced from the passive solar greenhouse underground. From the solar panels, they power a small electric heater and a weather monitoring system. Waterville, Maine is classified as zone 5b and the temperatures can get as low as -20 in January. The heater turns on when the temperature inside their greenhouse drops below 28 degrees. Michael also uses the weather monitoring system to study growing degree days inside of their greenhouse. Michael recently published an article in the American Bee Journal on his use of growing degree days as a hobby beekeeper.

Inside their sustainable greenhouse

Landscaping outside sustainable greenhouse in Maine

Every Growing Dome has a different environment. Inside their greenhouse, you will find jalapeƱos, a fish pepper plant, and many varieties of heirloom tomatoes, some of which are “roaring and almost 12ft high, which is unheard of for July in Maine.” Their tomatoes will continue to grow into late November. The Growing Dome has taken their produce to “the next level.” Michael said the giant fig tree in their center bed has been “satisfying” to watch, especially since they have never seen a fig tree thriving anywhere in Maine. The trunk is almost 8″ in diameter. He was particularly amazed by the pond. After adding water, it immediately stabilized the temperature in their greenhouse. He said the water has been “crystal clear” after adding a few water hyacinth plants for the goldfish and the solar-powered waterfall.

Joules to Dollars

college class in the sustainable greenhouse
Michael’s class in the Dome

Over the past seven years, Michael and Susan have done wonderful things with their Dome using it not only to grow food for themselves but also as a classroom. Michael is a professor of economics at Colby College, where he teaches a class of his invention called Joules to Dollars with fellow chemistry professor Whitney King. The course is “a scientific approach to the economics of sustainable energy systems.” In an average semester, 10-20 kids use Michael’s Growing Dome as a bioshelter lab! They “specifically keep track of energy consumption, temperature, humidity, and light levels inside the shelter. Outside the shelter, they measure temperature, rainfall, light levels, barometric pressure, and wind speed and direction.”

Susan has also taught courses in sustainable development and environmental history, among others, at Colby. Appreciating that ethics motivates action, she works with individuals in private practice to support people as they align their life choices with their deepest held values. She also leads retreats focused on ecology and spirituality in New England.

Advice to Future Dome Owners

Their advice to anyone interested in a Growing Dome is to “start with the plants you want to eat.” It can be very tempting to “try exotic plants right away and then get as big of one as you can.” Everyone always says this, but you don’t realize how true it is until you have one, and your excitement level skyrockets! It is better to spend your time on the plants you will eat regularly vs. learning to care for a unique plant. The time will come for more exotic plants. In summary, this experience has given Michael and Susan a “greater consciousness of use of resources and balancing the natural and man-made environments.”


You can find all of our Featured Growing Dome’s highlighted in our monthly newsletter “The Happy Grower,” on our social media platforms (Facebook and Instagram), and in our blog. At the end of the year, we create an annual calendar that includes every Dome of the Month. We send them to all Dome of the Month participants, along with a gift of Growing Spaces gardening goodies! Apply here. Have questions about a high altitude gardening? Send us an email to [email protected]

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