In another newsgroup, there's a discussion about heating a greenhouse.
Electric heaters were mentioned. Also kerosene, but comments were made
about fumes and stickiness. Someone recommended a plain propane barbecue.
It was stated that the CO2 would be good for the plants. I was wondering
about the CO produced, and what the levels would be.

What is the best/worst ways to do supplemental heat in a greenhouse?

Steve