Carbon dioxide is a chemical compound consisting of one part carbon and two parts oxygen. It is represented by the chemical formula, CO2. For a number of reasons, carbon dioxide is one of the most important gases on Earth. Plants use carbon dioxide to produce carbohydrates comprised of sugars and starches during photosynthesis. In photosynthesis, plants make use of light to break down chemical compounds and produce energy. Since humans and all other animals depend on plants for their food, photosynthesis is necessary for the survival of all life on Earth.

Credit for the discovery of CO2 goes back to the early 1630s. Scientist Van Helmont identified a gas given off by burning wood and gave it the name wood gas. Today, we know that gas as carbon dioxide. Helmont’s discovery was important not only because he first recognized CO2, but also because he first understood that air is a combination of gases rather than a single gas.

Later, some of the most complete studies of carbon dioxide were conducted by Scottish chemist Joseph Black. In 1756, Black proved that CO2, which was then called fixed air, occurred in the atmosphere and could form other compounds. He also identified carbon dioxide in the breath exhaled by humans.

The first practical use of carbon dioxide can be traced to an invention made by English chemist Joseph Priestley in the mid-1700s. Priestley found that by dissolving carbon dioxide in water he could produce a fresh, sparkling beverage with a pleasant flavor. Since Priestley’s discovery lacked only sugar and flavoring to make it into the modern soda pop, he could be considered the father of the soft drink industry.

After years of providing CO2 products to gardeners, I continue to hear stories of the benefits growers experience when they provide their indoor gardens with supplemental carbon dioxide. Here are some notes I’ve taken from the field.

Tiger lilies – A grower bought tiger lilies to plant outdoors, but never did. As summer came to a close, he brought the lilies indoors and placed the container in his grow tent. To his amazement, the lilies began to bloom, not once, not twice, but more than 10 times during that winter season. When new growth began, the lilies bloomed right above the surface of the soil almost immediately. The grower firmly believes the CO2 he added was the reason for the profound flowering.

Asparagus ferns – We once got a call from an avid greenhouse grower in Texas who said the growth rate of his asparagus fern had almost doubled after bringing in some extra CO2. He said he had been growing these ferns for years and could not believe what the added CO2 had done.

Christmas Bulbs – Most growers have heard of amaryllis and paper whites. These flowers are typically grown in the late fall for blooming around Christmas time. We heard from one grower who said that not only did added carbon dioxide produce healthy plant growth, it also doubled the amount of mature blooms ready in time for the holidays.

Tomatoes – In our facility’s research and development department, we have a tomato plant that has been in flower for more than three years. The plant has never been replanted and receives few nutrients, if any. If we remove the plant from its greenhouse, it begins to wilt and appear unhealthy. When placed back in its greenhouse with the added CO2, it begins to come back to life. This particular plant truly requires the added CO2 to remain healthy.

Orchids – Orchid growers on the east coast are able to manipulate the timing of flower production with the use of supplemental carbon dioxide. By introducing CO2 at specific times, growers are able to pinpoint the day their orchids will bloom and gain an edge at their flower competitions.

Pineapples – Living in Montana, pineapples are not something I think of growing. On a recent trip into town, I ran into an old college professor of mine. He began telling me how he had brought home a pineapple plant from Hawaii six years earlier. He purchased an all-natural CO2 product at his local grow shop and placed it next to the plant and was amazed to see that after a couple of weeks, a flower appeared. After that, a pineapple began to develop and the fruit matured.

Vanilla Beans – The cultivation of vanilla beans can be difficult even under optimal conditions, says an indoor gardener whose attempts had all failed. Having a vanilla orchid for more than eight years, he had never been able to get it to produce anything. Vanilla orchids will begin to produce after two to three years and become fully mature around year seven or eight. The grower decided to introduce CO2 into his grow space and that change alone made the orchid produce flowers. Vanilla beans take nine months to mature and another six months after harvest to cure.

Coffee Plants – Living in the Northern Tier, we do not think too much about coffee plantations, beyond enjoying a cup of good coffee to help get our day started. A gardener in our valley who had worked as a banker was given a coffee plant as a gift. She kept it in her office at the bank. After retiring, she moved the coffee plant to the sunroom in her home. For years the plant produced a coffee cherry here and there, but nothing that amounted to anything.

Hearing this, I told her she should try adding extra CO2. About a month later she called to say, “You’ve got to come see my coffee plant, it has beans all over it!” Since then, her coffee plant has continued to produce a steady amount of cherries. Within each cherry there are two coffee beans. With my help, she has harvested and dried enough beans to justify sending them to a friend of mine who runs a coffee roasting business. Is greenhouse coffee production possible? Maybe so.

Pumpkins – Pumpkins are the king of the squash family and are grown all over the world. Some growers produce small pumpkins while others grow giants. A giant pumpkin grower emailed me to say he was going to attempt to grow a record-breaking pumpkin. His goal was to grow a 2,500-lb. pumpkin. He added carbon dioxide to the greenhouse where the tiny pumpkin plants were starting their journey. Having experience with growing giants, he emailed back a couple of months later to say he did not think he would be as far along as he was if it had not been for the CO2.

What It All Means

All of these stories have an underlying theme. When you add CO2 to an indoor grow space, the benefits are huge. From strong, healthy seedlings to abundant flowers and fruits, plants will show you how much they love CO2. They cannot reach their potential without it. Any amount of CO2 you can provide your garden will greatly improve your yields. You and your garden will not be disappointed.