On 8 Dec 2005 16:31:21 -0800, Chuckie wrote:
I am hoping to grow plants with hydroponics starting in January. My
problem is that my greenhouse does not hold heat very well. I have
tried methods like hanging fans from the ceiling to pull the heat back
down to the floor. This works but not well enough if it is 30F outside,
the house is at 55F.

Heat the benches, not the air... you can get good growth with root zone
heating and a cooler air temp (with some crops, it's preferable.) One of the
Ball Red Books done in the last 10 or so years has a section on heating
costs and choices. Bubblewrap may also help with insulation
OF the house itself.