Since last year, juniors and seniors in Alan Carp’s honors engineering class at Kennebunk High School have been working hard to build and maintain the first off-the-grid greenhouse on school grounds.
The hoop house, characterized by its length, rounded structural shape and polyethylene material, has two rows of beds lining the interior walls.
“Without that money, we wouldn’t have been able to build it,” Carp said.
The honors engineering class was the brainchild of Carp, who is also the STEM coordinator for the high school, and high school math teacher Aaron Germana.
“He was starting his robotics program and we decided this would be an interesting addition for students to integrate math and science in developing a project,” Carp said.
This particular greenhouse is experimental, said Carp, meaning the focus is more on discerning what growing processes are most efficient rather than what crop the students are yielding.
For example, one row of beds has been watered by hand all year, and the other row has been watered by a solar panel powered sprinkler system. On Thursday, students were working on the final stages of programming a soil moisture sensor to bury in the controlled side’s soil.
Both rows of beds are being used to grow planted lettuce, catnip, chamomile, cauliflower and lavender.
The controlled side is watered by two tubes that stretch from one end of the greenhouse to the other. The problem is that the current system does not distribute water evenly. During last Thursday’s class, students brainstormed solutions.
“If you hang them higher, they will impede growth less,” said Matthew Fortier, a senior. “What if you cross the hoses?”
Junior Connor Shillington suggested covering the beds partially with holepunched taut plastic so that water would trickle evenly out each hole.
Another student proposed the idea of essentially a vibrating robot who would water one bed at a time. Noah Cimenian, also a junior, suggested uprooting the growth and burying the hoses so that water could seep into the soil.
As the students brainstormed, Carp stood by listening but refrained from intervening.
“It’s hard sometimes as a teacher not intervening and, instead, watching them make mistakes,” Carp said.
The greenhouse is powered by a large solar panel. It powers a battery, which aids the sprinkler system and heats water that runs through pebbles underneath the beds to keep the plants warm in the winter and at night.
Attached to either side of the greenhouse’s exterior are two rain gutters that drain water into three barrels.
During a decent-sized rainstorm, the six barrels will fill about halfway, Carp said. The gutter system was also devised by students.
The informality that spurs spontaneous group discussion and decision making, along with the hands-on curriculum, are an integral aspect of the curriculum in honors engineering.