QuestionsHow to growGreenhouse GrowingHeating and VentilationGreenhouse Shading 0 Vote Up Vote Down Sean O Connor asked 16 years ago what is the best material for greenhouse shading? Would old white net curtains be okay? 1 Answers 0 Vote Up Vote Down Gerry Daly Staff answered 7 years ago Shading is most effective when placed on the outside of the glass so that the heat energy does not get inside at all. Use Coolglass to spray or paint on the outside and wipe off at the end of the year. Old curtains probably would serve well enough.