Other than installation and occasional maintenance costs, geothermal greenhouses are minimally expensive. Passive geothermal warming doesn't require energy costs to run or transform into another more effective form of energy.
The cost of a mostly passive geothermal greenhouse will depend on the size of the greenhouse(s) and somewhat on the topography of the land. The primary cost of the passive geothermal element is generally excavation and burying. Piping can be simple corrugated plastic sewer tubes, and most of the manual labor is laying and connecting the pipes to the greenhouse intakes.
