The thermal behavior of a perlite bag from a Mediterranean soilless protected crop is described. A TES system with PCM to heat plants roots in soilless crops is studied with multiple experiments. The best PCM phase change temperature for the application seems to be 15 °C. The most effective PCM location consists of wrapping the perlite bag. 20–30 Kg of eq. CO2 emissions could be saved per hectare and night.