[cameron_b]

Most Greenhouses supplement CO2 to increase growth in plants since there's no natural O2 -> CO2 back-cycle in the greenhouse. So yes, Greenhouses use CO2.

Reference in Commercial Greenhouse Industry - https://www.greenhousemegastore.com/equip/co2-generators/

[LegitShady]

That's not why they're called greenhouse gasses, though. They create the greenhouse effect for the entire planet.