I'm pondering what I might do to more efficiently heat my small
greenhouse to a minimal extent (40F). With the increase in the price
of natural gas I wonder if electric would be about the same? I also
want to consider assembling a table with a clear plastic cover to
contain the heat to a smaller area. Perhaps I could create a heated
table top? That would be useful next Spring. I suppose resistance wire
in a thin bed of sand?

Dave