How does CO2 help increase marijuana yields?
Cannabis gets its mass from the air, not from soil or fertilizers. Dry cannabis is 90% carbon and oxygen captured from the atmosphere. Only 2% of elemental mass is fertilizer. That’s why CO2 enrichment is the best supplement you can give your plants. When plants get extra CO2 they grow bigger, faster and are more tolerant of high temperatures.
Carbon dioxide increases yield because it is the raw material for photosynthesis. Sunlight powers the chemical reaction in chlorophyll that transforms CO2 into useful plant sugars. Plant sugars –carbohydrates– are both the fuel for, and building blocks of growth. Oxygen is a byproduct of photosynthesis.
The atmospheric CO2 level in outside air is roughly 400 parts per million. But cannabis has the ability to thrive in levels much higher than that! Doubling that concentration causes a major increase in photosynthesis rates. These gains decrease at concentrations beyond 1000 ppm. At 1500 ppm, CO2 becomes toxic to plants. Plants only use CO2 during the day, when lights are on and stomata are open.
Biological Sources of Supplemental CO2
Humans are a biological source of CO2. We do the opposite of plants: we breathe in oxygen and exhale CO2. Every time you tend to your plants, you are increasing available CO2 in the garden. Pets, rising bread and fermenting beer exhale CO2 too. The problem is that these biological sources are only available sometimes. Your entire family would need to live in the garden 24/7 to be a significant source of CO2.
Living with your plants isn’t an option for most people. Luckily there are alternatives. Fungal mycelium are a biological source of CO2 that operates continuously. The ExHale 365 Self-Activated CO2 bag is pre-packaged, living fungal mycelium culture. It provides enough CO2 to support an enclosed 4’x4’ garden. You simply hang the bag above the plant canopy and it will fill the garden with CO2 for 6-9 months. Exhale bags are easy to use, don’t need electricity nor emit heat. But mycelium culture is only an option for small gardens with one or two grow lights and only a few cannabis plants.
Bottled CO2 is much more effective and reliable than biological sources. It is the most common source of CO2 for atmospheric supplementation. That’s because it is convenient, effective, and has low upfront cost. It doesn’t generate heat either. CO2 tanks are simple to install and don’t require infrastructure upgrades. The gas is a recycled byproduct of other industries which minimizes environmental impact.
Bottled CO2 requires frequent purchase and delivery of pressurized CO2 tanks. Reliance on a gas supplier makes frequent CO2 deliveries an ongoing expense. CO2 tanks are available at grow stores and from industrial gas suppliers. Industrial cultivation facilities need permanent storage tanks refilled via tanker truck.
Bottled CO2 requires a regulator to control the rate that it is released from the storage tank. The regulator also turns gas flow on, or off, via an electronic switch. This switch connects to the CO2 controller.
The controller activates the on/off switch on the regulator. It turns the regulator on when CO2 levels are low, and off when they are too high. It works like a thermostat, only its sensors track ambient CO2. Simply set the desired CO2 concentration and the controller takes care of the rest.
CO2 generators create supplemental carbon dioxide by burning propane or natural gas. On-site CO2 generation is the cheapest long-term option because it eliminates CO2 deliveries. The downside is a larger up-front investment and installation cost.
CO2 generators need a dedicated natural gas line, or a connected LP gas tank . That can make installation expensive if you don’t already have gas service to your garden. You might want to hire an HVAC professional to install and connect your CO2 generator to the gas supply.
Burning fossil fuels creates heat in the grow room. One generator emits 22,163 BTU/hr. That’s roughly equal to four electric space heaters. CO2 generators are an extra burden on air conditioning. You may even need to install more air conditioning to handle the thermal load.
Carbon Dioxide Supplementation only works in a sealed grow room. Adding supplemental CO2 to a vented grow room is simply a waste of money–intake and exhaust fans quickly remove supplemental CO2. That’s why you will want zero air exchange with the outside world to effectively boost atmospheric CO2. Air conditioning and dehumidifiers keep heat and humidity in check without leaking air. Seal all gaps and cracks in the grow structure to keep valuable CO2 contained within the garden.
Or Go Au Natural
Ambient CO2 is already higher than at any other time in human history. Fresh outdoor air is an abundant and free resource for your garden. Cannabis evolved to grow at natural, outdoor CO2 concentrations. All you need are intake and exhaust fans to continuously replenish air inside the grow room. Vented gardens are an economical and reliable way to grow cannabis under normal atmospheric conditions.
Liebig’s Law of the Minimum states that growth is controlled by the scarcest resource. Supplemental CO2 will do nothing for your plants if they are deficient in a lower need. It is ineffective if plants lack correct environmental condition, good water, appropriate fertilizer and abundant light. CO2 supplementation only generates a return on investment in completely optimized, hi-tech gardens.