The heating system in the greenhouse is connected to the house. I have oil heat/forced air coming out of 3 registers on the greenhouse floor ( actually a couple of inches above the floor, so I don't have water running into them) with a higher placed return flow. (The ducts are pulled from the oil burner in the basement into the garage and upwards in the greenhouse) That alone provides plenty air circulation, especially on cold Winter days and nights when the heater kicks in more often. That and the greenhouse has a glass ceiling which lets in maximum light.
In addition I have a rotating fan ( set on low) mounted high on the wall.
Right now I water every day thoroughly, I will slow down on cloudy days when the temps outside reach the fifties F or so. But right now the Orchids don't stay wet for long at all.
Remember that one side of my greenhouse also houses a C&S collection....the Pachypodiums and Adeniums are waking up btw.
