The amount of carbon dioxide a plant requires to grow may vary from plant to plant, but tests show that most plants will stop growing when the CO2 level decreases below 150 ppm. Even at 220 ppm, a slow-down in plant growth is significantly noticeable.
Below that, chlorophyll based plants die, life on earth for most plant and animal species ends.
Under 220 ppm, plant growth is stunted greatly.
Current CO2 level is not even 400 ppm, plants grow best 1000 to 2000 ppm.