The Garden Tower is a compact plant growing system that uses a stack of rings organized around a central compost tube to grow a variety of vegetables, herbs or flowers.

Colin Cudmore, inventor of the Garden Tower, and company co-founder Joel Grant joined others in adding compost, soil and plants to the Garden Towers as well as building the greenhouses and getting all the pipes, water containers and other items needed to create the five different greenhouses.

“We have four different designs we’re looking at and a control greenhouse,” Grant said, adding that the goal is to discover what system produces the most heat. “It’s our first stab at creating an outdoor lab,” he said. The hope is to be able to provide information on the best way for people to create their own naturally heated greenhouses without the use of fossil fuels.

“We’ve developed various designs that are very simple to build,” Cudmore said. The basic concept is that heat generated from the compost inside the greenhouses will heat the greenhouse and allow it to be used year-round, even when it’s very cold outside.

There is a “control” greenhouse that was built without any attempt to use the heat from the compost to keep the greenhouse warm. The other greenhouses use different designs and materials to try to capture heat and maintain a warm environment inside the greenhouse. Some of the items used include wood debris, sawdust, grass clippings — all items that would be readily available to many Americans.

“You don’t realize there are sources of biomass that people can get in most communities,” Cudmore said. “What we’re really focusing on is what people can use.”

Cudmore said adding a little bit of manure to wood chips, mulch or grass clippings “kicks off” the composting process, which produces heat. That is the basis for heating the greenhouses, although some of them contain pipes and containers filled with water because water is better at keeping and storing heat.

“We’ve not invented the concept of heating a greenhouse using compost,” Cudmore said. What he and the others hope to do is make community agriculture more sustainable for average people so they can use the materials around them, provide themselves with food they grow themselves and be able to maintain their greenhouse, whether it’s 70 degrees outside or in the middle of a blizzard.

The size of the greenhouse was chosen because it’s not too large for most homeowners — many people could find a place on their property to set it up. The Garden Towers, with about 50 plants or more, have a footprint of about 4 square feet of space. More plants or more rings to the tower can be added to increase the number of plants grown in the greenhouses, said Cudmore. “It’s easily big enough to supply food for a family.”

All the materials used in building the greenhouses and their internal structures are readily available at local hardware stores, so anyone will be able to build them, Cudmore said.

Now that the project has begun, the Garden Tower folk and some volunteers will be watering plants and checking the moisture content, temperature and other data. What’s needed now, Cudmore said, is a couple of months of data to show which systems are producing the most heat inside the greenhouses.

Once that’s determined, probably in the spring, a new tutorial giving the specifications and building instructions for the best greenhouse will be compiled and shared by mid-summer, Cudmore said. All the information will be open source on the Garden Tower website, so others can use it and possibly even improve on it, he said. “I’m just one inventor. Somebody will probably come up with a better system. I’d like to encourage that.”