Does anyone have a source for a waterproof programmable termostat for
a greenhouse that can control a 110v heater?

After more than thirty yers of growing in a GH, I have had umteen units , in
ALL price ranges, with cheap ones lasting as long as the expensive ones, and
currently I have a digital which can regulate 4 different time intervals, and
cost about 1/3 of the top of the line-works just fine. See at Sears.
Wilford Neptune