Not very often. Just watered today and its first time for many days I think 7+. I have this soil moisture meter and I wait until it gets to like real dry then I water.
I had problems getting humidity up (its at 20-30%) so I used to use this humidifier that sprayed water vapor. The leaf that you see on there was right next to the humidifier, the water vapor was spraying directly at the plant/leaf. I figured earlier it was some kind of chlorine residue since I am just using tap water in the humidifier but my friend told me today he thinks its PM.