The objective of this study is to examine the feasibility of greenhouse heating with geothermal heat pump (GHP) systems. Both closed- and open-loop systems are examined at four locations across the U.S. and a net present value analysis is conducted for a 20-year life-cycle for various GHP base-load fractions. Results show that it would only be under situations of relatively low ground-loop installation costs and/or relatively high natural gas costs that some portion of a greenhouse could be economically heated with a closed-loop GHP system. At natural gas costs of about $0.60/therm ($0.21/m3 ), no fraction of a closed-loop GHP system is economically feasible for the cases examined. At natural gas costs from $0.60/therm to $1.00/therm ($0.21/m3 to $0.35m3 ), closed-loop GHP systems begin to emerge as economically viable, but only at low loop installation costs, on the order of $5.50/ft ($18/m)