Would lining the outside of a thin plastic garden pot that is exposed to full sun with 20 mm Styrofoam keep the heat out and prevent the soil from drying out quicker, OR would it do the opposite by retaining the heat in the pot and, therefore, making the soil dry out sooner?
Water Saving Question
Certified GKH Gardening Expert
While I cannot say with certainty, I believe that it should help insulate the plant roots from extreme heat and cold but will still require plenty of watering. Container grown plants need to be watered more often, regardless, especially in high heat situations. So, adding a foam liner will help but keeping the plant watered, and even mulched, will help prevent it from drying out faster.