Kenni Judd wrote:
At the risk of getting into all kinds of trouble ...

It sounds to me like lots of you are wasting a lot of $$ on excess heat. I
know many of you have longer, colder winters than we do. But
even here in South Florida, we _do_ get some cold nights. As a business, we
heat to 55F (lots of reasons, most of which wouldn't apply to a hobby
grower)..

But most of our hobby-grower customers don't worry about heating above 40F,
nor did we in our backyard days.

You have some chilly nights, but does it usually warm up the next day?
Plants may well tolerate temperatures in the 40s for a few hours, if
they warm up into the 70s the next day. But what if they stay cold?
On short, cloudy northeastern or midwestern winter days, there may not
be enough solar heating to push the temperature much above the
night-time low. With a minimum night time temp of 55-60 that may be
enough to keep the plants ticking over, even if they aren't growing
much. But, if the temperature drops to the 40s at night, the grower
will probably have to run the heater during the day to get the
temperature up (thus negating some of the savings).

Sunny days are, of course, no problem, but I prefer to set the
thermostat once, rather than running out to change it whenever the
weather shifts. My most expensive month is December, which tends to be
cloudy. By February, the days are usually sunny enough for significant
solar heating, even though the nights are still cold. Other peoples
mileage may vary, but I start to lose plants and/or have problems with
bacterial rots if I set the thermostat much below 60.