Heating: Hot Water Radiant Heat
Depending on your growing needs such as crop locations (on floor or bench) as well as multiple zone(s) hot water radiant heat is a great value. Costs are relatively reasonable and paybacks are quick with an efficient hot water system that places the heat closer to the plant.
The use of hot water radiant floors allow the grower a more uniform and constant source of heat at the crop, not 10 to 12 feet up in the air. If the greenhouse area is broken up into multiple zones your system can be designed to accommodate different environments for different crops being more efficient.
A variety of boiler options are available with different fuel options including different biofuels.