This paper describes the use of a low enthalpy geothermal source in Northern Greece to heat a greenhouse where flowers could be grown, especially roses. The different parts of the developed greenhouse, the heat loss calculation and the heating system are described. An analysis is given of different greenhouse heating approaches, and a description of the selection procedure, following low-cost and high-efficiency criteria. An analysis is also made of an extended heating system, which uses low temperature water or direct geothermal fluid to heat a second greenhouse similar to the first. The second greenhouse could be used for strawberry cultivation, where an inside temperature of 15 degrees C is required. The existing greenhouse, described in this paper, proved to be very important and beneficial for this area of Northern Greece, with its numerous low enthalpy geothermal sources.