In my greenhouse (3 1/2 years) i have always relied on natural solar heat
gain ,i kept the greenhouse heater set at approx 60 f and let the sun do the
rest.Obviously there are times when there is no heat gain for a few days
,but havent seen a adverse affect with this ,although more careful
watering/spraying is needed.I have had good flowering too,i am now keeping
the greenhouse at 50f as i am now going cool so the temp difference should
be easier to achieve.At this time of year in the UK on sunny clear days the
temps rise to approx 60f in the greenhouse.All the books state the heaters
need to be set for a daily temp difference and other growers i know do
without fail .I havent had any problems to warrant me to unaturally set the
daily temp higher.
What do others do and what experiences have you had with either way of
trying to achieve the temp diff.
By the way my reason for not raising the temps other than solar is financial
and it does`nt seem natural to raise temps if the sun light is not there.
Any others with pro`s and con`s with first hand experience will be an
interesting read ..

Thanks Keith