[Caretaker]

I have a 6x4 small greenhouse, on one bench I have my home made propagator with a heating cable temp set at 20c.
On the small shelf at the end I have my electric fan heater set at frost control.
 Now as the weather is looking fairish, I was thinking to turn the cable down or off, as it is drying out the seedlings.
Any tips on what to do.
I do water every day but only a little but I am home all day, the joys of retirement.