Abstract The authors assume that determining temperature distribution and heat flux directions in the ground beneath a greenhouse can help to establish the role of ground in its thermal management and explain how soil temperature of cultivated plants is shaped. Measurements of temperature distribution in the ground and in the air were conducted in a greenhouse situated in the south of Poland. Both the foundation as well as the floor has not been thermally insulated. The greenhouse has been adjusted to biennial flower cultivation. Results of air and ground temperature measurements along the vertical and horizontal measurement planes are presented in a graphic form. The observed temperatures and directions of heat transfer in the ground helps to explain the mechanism of heat flows to and from greenhouse during the whole year. In particular heat losses in winter and stabilizing of inner air temperature through heat buffering in summer periods and during intermittent heating in cold periods. Estimated heat exchange with the ground is very small in comparison with heat flows through transparent thermal envelope and does not essentially influence thermal balance of the greenhouse.