I know that a greenhouse is not air tight so I imagine it breathes somewhat and exchanges gas with the outside. However, I also assume that it’s going to use up the co2 in it for plant growth. How does it not run out? I think you could vent it, but then wouldn’t that cool it off and thus defeat the purpose of a greenhouse? All my web searches either give climate change facts or co2 supplementation by farmers.
Plants only absorb CO² and release oxygen when photosynthesizing, which requires sunlight. At night plants undergo cellular respiration where they absorb oxygen and release CO². Some sealed terrariums haven’t had any water, air, or fertilizer for decades.
https://laidbackgardener.blog/2019/10/14/the-worlds-second-oldest-sealed-terrarium/
Mostly it’s fine as others have stated, but sometimes they pump CO2 in there. One example is Friðheimar tomato farm in Iceland, which enhances photosynthesis by using carbon dioxide produced from natural geothermal steam.
I guess same as you get enough oxygen at home even if you don’t open the doors and windows at all.
It’s called diffusion. Unless the greenhouse is hermetically sealed, and the rate of consumption does not exceed the rate of diffusion, the ratio of CO2 will be similar to that outside.
A simple vent will be enough if not just small gaps in the structure.
Also, most green houses have fans that can help circulate air in from the exterior.
Plants don’t actually use up all that much CO2. An entire greenhouse worth of plants wouldn’t even consume as much CO2 as your body produces. Most oxygen produced on earth and CO2 consumed is done by algae. Land plants like trees can sequester more CO2 because they grow larger and use it to build their bodies but they do so slowly over the course of years.
So I guess plants don’t suffocate in greenhouses for the same reason that you wouldn’t if you sat around in a greenhouse. There is enough air infiltration through cracks and gaps in the walls that sufficient air gets exchanged to keep it breathable.
Most oxygen produced on earth and CO2 consumed is done by algae.
Thats more because of total biomass, and the difference is we’re basically a ball of water.
The same reason your house isn’t a pure “air” environment.
Carbon Dioxide is heavier than all the components that make up the air you breathe. In a greenhouse they have fans that move air around, because stagnant air would generally be bad for both plants and humans. You’ll notice a gap in all greenhouse environments to the ground.
CO2 gets pulled in, but eventually pushed out because of its weight, but enters in from the ambient atmosphere being injected by the fans.
