i creat co2 by breathing on them AND putting a teaspoon at a time in a small bowl of BAKING SODA and VINEGAR. that gives it a good small shot of co2 if you have a smaller growing area,,,,,plus i put a CANDLE in a empty COFFEE CAN (i like small tea lighs or the religious kind in glass, they burn better) and it burn oxygen and releases co2!!! of course that happens ONLY when i'm in the area and can monitor it off and on. hope this couple other ideas help to give your plant co2