Why CO2 Matters for Your Grow Tent & How to Add It?

As cannabis cultivators, we are always on the lookout for ways to improve yields and enhance the quality of our harvests. Show me one grower who wouldn't love an increased yield, better quality buds, and the ability to grow more plants per year! Well, there is a way to knock all those targets down with one stone—introducing carbon dioxide (CO2) into your growing environment. Often referred to as the "fuel for photosynthesis," CO2 is crucial for plants, helping convert light into the sugars needed for development. Mastering CO2 supplementation can take your grow operation to the next level.

Importance of CO2 for Grow Tents

CO2 supplementation is not a necessity for growing cannabis. However, with as many benefits as it offers, you would be hard pressed not to consider it! In a controlled environment, like a cannabis grow tent, CO2 supplementation offers unique advantages. 

Properly implementing CO2 enrichment can lead to faster growth, higher potency, increased yields, improved stress tolerance, and even shorten growth cycles! 

A study on Crop Physiology at Utah State University, has discussed the benefits of CO2 supplementation in controlled growing environments. It notes that increasing CO2 levels to approximately 1,200 ppm can lead to significant yield enhancements, with some studies indicating increases of up to 30%. 

CO2 also requiress for the grow lights to run at a higher intensity, and environment to be kept a little bit warmer. Both increase cellular activity and lead to more and faster growth. This practice is particularly beneficial for indoor cultivation, where space, light, and airflow can be meticulously managed. 

Should I Use CO2 for My Tent?

The simple answer: YES! There are many different ways, and solutions to utilize CO2 in your grow tent, the benefits are hard to pass on!  

Even if you decide not to use CO2 supplementation, you need to make sure the plants are getting some source of CO2. This is typically done via air exchange fans, or fresh air intakes going into the tent! If no fresh air or CO2 supplementation is used, the CO2 levels will naturally deplete over time due to plant respiration. Without additional CO2 or air exchange, the plants may experience a drop in growth rates.

Different Types of CO2 for Grow Tent

There are a few different solutions to using CO2 in your grow tent.   

Hot CO2

Hot CO2 is typically used in large-scale rooms and facilities. Hot CO2 is created by generators that use pilot-burners to combust gas. Once the gas has been cobusted, the byproduct is CO2! These burners have the highest and quickest CO2 output but require a monitor or controller, which can get pricey. However, this also allows for automation, keeping CO2 levels in optimal range at all times without the need of constant monitoring. 

Since these burners use a flame to generate CO2, you also need to account for the increased cost of environmental control that will be required to offset the heat generated, and cost of gas used to generate the CO2. CO2 burners are available with 2 options for gas consumption: LP (liquid propane) & NG(natural gas). Be sure to choose the one that fits your situation best!

***NOTE: Do not switch out parts between LP and NG units. Using LP burner tips on an NG generator can cause ethylene output instead of CO2, which can be harmful to humans.  

Cold CO2

Cold CO2 comes in the form of compressed gas tanks. This is the simplest and easiest way to utilize CO2. All you need is a CO2 tank, a timer, and a silinoid that slowly leaks the gas into the grow tent. 

However, compressed tanks are also the most expensive way to use CO2—sometimes costing up to 4x more depending on the volume. 

Organic CO2

Organic CO2 generators, such as mycelium bags that naturally release CO2, yeast reactors, or baking soda solutions, are the most inexpensive solution to introduce CO2 into a grow tent. However, they are also the least efficient, making them only good in micro grow environments. While these items are relatively cheap and easy to use, they won't give off enough CO2 for a grow room or tent. 

How to Add CO2 to the Grow Tent?

Once you have chosen your CO2 enrichment solution, you will need to know how to precisely utilize CO2 to your grow tent's advantage. 

CO2 concentration, light intensity, and the plant's tolerance to temperature have a direct linear realtionshsip. As the CO2 level increases, the plant's ability to use more light and tolerate higher temperatures improves correspondingly. Therefore, the plant needs higher temperatures and stronger light as a driving force for proper photosynthesis rates while enriching with CO2. 

When adding CO2, it is commonly recommended keeping your lights PPFD output at equilibrium to your CO2 ppm. For instance, if you're going to enrich the growing environment with 1,000 ppm of CO2, make sure your grow light's PPFD output reaches 1000 PPfD(μmol/m²/s). If you're looking to max out your growth potential, the highest you should push the plant with CO2 is 1,500 PPM of CO2. To be succedfull doing so, you will need grow lights that can match that 1,500 ppm level with 1,500 PPfD output. 

Under typical conditions with a baseline carbon dioxide concentration of about 400 ppm(ambient level), the optimal growing temperature is around 80°F. This changes once you start to enrich CO2 concentrations above 1,000PPM. The CO2 allows plants to grow as high as 96°F, where photosynthesis reaches its peak. However, remember terpenes are highly coltile and sensitive. They start evaporating around 78 °F. So it's not always beneficial to keep temperatures beyond that level. Most indoor cannabis growers agree that a temperature of 86°F is ideal for both growth rate and ease of management, until you enter the later weeks of flower development.

When to Use CO2 in Your Grow Tent?

CO2 supplentation can be used from the beginning of the veg stage, all the way until flushing starts! 

However, most growers find the CO2 enrichment during the veg stage isn't worth the cost! It's most important and impactful during flowering. In late flowering, CO2 enrichment becomes less impactful because the plant’s growth slows down and it shifts focus to ripening. CO2 is absorbed by plants while they are receiveing light (photosynthetically active). At night, plants switch from photosynthesis to respiration, taking in oxygen and releasing carbon dioxide. So during night, CO2 enrichment is also not beneficial. 

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