I wish I had taken pictures of a couple of the 8" clay pots where I have bromeliads growing. If you knew what that clay-covered white, powdery mold looked like (and felt like), I can assure you, you would have headed for the bleach. They were really gross and it seems that the mold appeared within just a few days. I divided some older bromeliads and potted up these divisions in new clay pots. These pots were in the solarium. I have never seen my clay pots get "attacked" by mold like this in my greenhouses. I have a feeling that better air-movement and perhaps the higher heat in the greenhouses were the differences.
