For greenhouses - Most crops the saturation point will be reached at about 1,000–1,300 ppm under ideal circumstances. A lower level (800–1,000 ppm) is recommended for raising seedlings (tomatoes, cucumbers and peppers) as well as for lettuce
Are you saying that the plant died because Co2 exceed these levels??
Water is also a poison. How much do you have to drink to kill a person??? Look it up.
