I am trying to grow vegies inside for winter. They are in a sunny window, and I use a grow light at night. They are in a room with the woodstove so its fairly warm at night (68-72). Today I went to water and there was Mold? White on the outside of the clay pots. I thought about wiping it off with vinegar. What would cause this overwatering? We have had lots of rain and snow this week.