I think it may not revive the current ones, but it would certainly help any new ones. I had to bring 2 calathea inside from the greenhouse in the summer, most don't mind the intense heat out there, but these specific ones are unidentified species that do not seem tolerant of extreme heat. I put them into 2 small sealed terraria and they love it. The box has a layer of Aliflor (LECA) on the bottom about 2" thick and then is filled to the soil line with water. Once the doors are closed, the natural heat from the sun shining through the window causes about 90+% humidity. Its the same principle as a cloche, but you can't always find cloches large enough for a nice sized plant.
