DIY Carbon Dioxide CO2 Generators

Plants use light energy to convert carbon dioxide and water into glucose and oxygen. They do this so efficiently that in an enclosed space like a greenhouse, carbon dioxide becomes scarce enough to slow growth and yield. The solution is to produce carbon dioxide by artificial means. The difference can be quite dramatic; commercial tomato growers have reported that yields improve up to fifty percent with carbon dioxide generation. While home gardeners don’t usually have the thousands of dollars to buy natural gas-burning commercial C02 generators, there are at least three much cheaper methods for bringing more carbon dioxide to backyard beds.

Supplies to Make CO2

For Method #1:

• Dry ice, at least 4 inches in diameter
• Pie pan

For Method #2:

• 2-liter bottle(s)
• 1 to 2 cups baking soda
• 1 to 2 cups vinegar

For Method #3:

• 2-liter bottle
• 1 package dry yeast (1/2 tablespoon)
• 2 cups sugar
• 1 T baking soda (optional)

Method #1: Use Dry Ice to Generate CO2

Put a pie pan on a shelf or platform very near and slightly above plants, so that heavier-than-air CO2 will reach as many leaves as possible, where stomata take in gases. Place dry ice in the pan. Add warm water. As the dry ice sublimates into CO2, close up the greenhouse to limit gas dispersion.

Method #2: A Chemical Reaction which Makes Carbon Dioxide Gas

Pour 1 to 2 cups of baking soda into a 2-liter bottle. Place the bottle slightly above and very near plants. Pour an equal amount of vinegar as baking soda into the bottle. As the resultant fizzy chemical reaction produces C02, close up the greenhouse to limit gas dispersion. As the reaction slows, shake the bottle to stir the contents and speed the bubble production again.

Method #3: Yeast Produces CO2 Bubbles

Pour sugar into a 2-liter bottle. Add yeast and shake to disperse the contents evenly. Fill the bottle about two-thirds high with warm, filtered water. Add baking soda, if desired. Put on the cap and shake well. Place the bottle in the greenhouse, slightly above and very near the plants. Remove the cap. Every day or so, shake the contents of the bottle to bring the yeast into contact with more sugar.

Keep Making CO2

Replenish the CO2 generators as needed. Use the first and second method for single, large doses of carbon dioxide. Use the third method for continuous slow dispersal of the gas over a one- to two-week period.

Record the changes in plant growth and yield with the extra CO2 against a control planting grown without. Make note of which crops react most favorably.