The tomatoes aren’t cooperating. Instead of growing up the trellis, the plants are weaving all over the garden bed and arching, menacingly, toward a young grapevine. On a hot August afternoon, Pauline Benetti and Diane Kelsey are trying to coach the fruit upward by tying its stems to the wood-and-metal trellis.
It’s high season for the juicy red spheres, but these two volunteers – both shorter than the vines they’re trying to wrangle – aren’t just struggling with these plants for the final farmers’ markets of the summer. They want to train the tomatoes to grow in the right direction inside this greenhouse all year long.
Their work is part of a five-year effort by the Geothermal Greenhouse Partnership (GGP) in Pagosa Springs, Colorado. The volunteer-run nonprofit, in coordination with the south-west Colorado town, is transforming the world's deepest geothermal hot spring into something much more than just a travel destination: it’s using the renewable energy source to grow food year-round for the community.
Pagosa Springs is well-known in the western United States for its unique approach to geothermal energy, which is energy harnessed from the Earth’s heat. Geothermal food growing, though, is a new enterprise.
In the centre of the small downtown, on the banks of the San Juan River, sit three conspicuous, geodesic greenhouses, each 42ft (13m) in diameter. They stand in stark contrast to the old-timey buildings on the road above. All will house gardens, but each has a different mission.
The first, the Education dome, was built in 2016. It is the only one of the trio that’s currently operational. Volunteers stop by to prune and plant every day; more than 300 students have visited the site to learn about the plants and to practice their maths or science skills; and the public is welcome from 11:00 to 14:00 on Tuesdays and Saturdays.
“Everything we do is [focused on] teaching sustainable agriculture to the next generation and growing food year-round – which is pretty special” at an altitude of 7,150 feet (2,180m), says Sally High, a former environmental educator and GGP board treasurer.
The geothermal water comes from town wells via a lease agreement with Pagosa Springs. A heat exchanger inside each greenhouse uses the geothermal liquid to heat domestic water, which is piped through the floor of the greenhouse in cold-weather months. The geothermal fluid then resumes its natural path.
The closed-loop system is as close to non-consumptive as possible – meaning almost no water is consumed during the process, with most of it returning to the ground – and allows the greenhouse to maintain a consistent temperature that ranges from 58F (around 14C) on the coldest winter nights to 90F (32C) on a sweltering summer day. (A pond, fans, misting system, and windows also help regulate the temperature.) That means the squash, kale and beets can grow in any month – a major benefit in a high-elevation mountain town where the average frost-free growing season spans less than 80 days.
The method will be similar in the Community Gardens greenhouse, which is expected to open before the end of 2018. Local civic organisations and community groups, such as food banks and veteran-focused associations, will have their own garden beds in which they’ll grow food to help feed their communities.
The Innovation greenhouse, slated to open in 2019, has a different purpose. It will house anaquaponic growing environment, raising fish and plants together in a symbiotic system in which the fish waste acts as a food source for the plants while the plants filter the fish’s water, one that uses about one-tenth of the water required for conventional soil growing. It’s a controlled environment, so the dome will be closed to the public except during special demonstrations or tours.
Our geothermal resource is underused and undervalued – Sally High
“Farmers’ markets are seasonal. This takes Colorado’s agriculture [towards being] very local and year-round,” says High, who sees Pagosa’s greenhouse endeavour as both an economic and tourism driver for the town. “Our geothermal resource is underused and undervalued.”