Does Carbon Dioxide Increase Cannabis Yield?

Add more CO₂ to our lives and we have global warming at hand. None of us want that. But unlike us, CO₂ can actually be quite beneficial for your cannabis plants. While we’re here wondering how to keep CO₂ levels in check, your cannabis plants see it as the ultimate growth booster. 

But like many things, it’s easy to wonder — does it really work? The short answer is yes. Read on for the long answer. In this article, learn how CO₂ can help your cannabis plant, and how you can use it to your plant’s full advantage. 

Does Carbon Dioxide Really Boost Cannabis Yields?

Cannabis plants, like all plants, take in carbon dioxide (CO₂) through tiny pores on their leaves called stomata. These stomata act as little mouths that allow CO₂ to enter, which the plant uses for photosynthesis. 

During photosynthesis, CO₂ combines with sunlight and water, allowing your plant to produce oxygen (which we breathe) and glucose. Think of glucose as the plant's personal fuel — it powers its growth and helps it build stronger roots, stems, and leaves.

In most grow rooms, CO₂ levels hover around 410 parts per million (ppm), which is generally enough for cannabis plants to grow well. However, if you’re aiming for larger yields, you can boost that CO₂ level. 

With higher CO₂ levels, plants can produce more glucose, which translates to faster growth and bigger, fuller buds. But there’s a catch — CO₂ alone won’t do the trick.

To make full use of the extra CO₂, your plants will also need high-powered lighting. Without sufficient light, the additional CO₂ can't be processed effectively, which can actually end up harming the plant rather than helping it. 

So, if you’re ready to fine-tune your grow room, carefully balancing CO₂, light, and water can yield big returns in plant growth and flower density. Just remember: dialing up CO₂ levels only works when all other growth factors are well-aligned — otherwise, you’re just feeding the plant more than it can chew!

Pros of Adding More CO₂ for Cannabis

Before anything, know that carbon dioxide will not boost your plant’s THC or cannabinoid levels. However, your plant can still benefit in various ways with additional CO₂ that can all equal more yields. Here are some of the pros of using CO₂ for growing cannabis:

1. Increased Photosynthesis Efficiency

Plants use light energy, water, and CO₂ to make glucose and oxygen through a process called photosynthesis. When CO₂ levels are higher than ambient levels (which are around 400-450 ppm) in cannabis cultivation, the plants are able to fix more carbon, thereby creating more energy. This energy helps all growth functions even when demand is high. This is evident during the vegetative stage when the energy requirement of the plant is highest.

2. Higher Yields

CO₂ helps the yield at the final stage of production and the development of flowers. Thanks to greater photosynthetic activity, it results in abundant carbohydrates that are essential for the formation of buds. Researchers have estimated a 20-30% increase in yield when levels are increased to 1,200-1,500 ppm over non-enriched conditions. This can be even more effective in controlled settings that optimize light and nutrients.

3. Faster Growth Rates

Cannabis plants can speed up their metabolism and increase the rate at which cells multiply and lengthen when given a lot of CO₂. These results speed up vegetative growth, hasten flowering, and may reduce total cycle time. In commercial grows, you can save time with faster cycles and have more harvests three times per year. 

4. Improved Bud Quality

Higher CO₂ levels can increase resin production in cannabis plants. Resin is enriched with cannabinoids such as THC and CBD and terpenes responsible for flavor, aroma, and potency. Growers notice that adding more CO₂ means buds become denser, stickier, and heavily covered in trichomes, which are great for the medicinal and recreational markets. 

5. Better Performance Under Bright Lighting

Cannabis plants can use excess light only if there is enough CO₂ available. Ambient CO₂ can limit plant growth in setups with intense light using LED and HID lights. More CO₂ means plants can saturate light better and avoid photoinhibition, which occurs when light energy exceeds the plant's ability to use it and causes damage. 

6. Resilience to Stress 

Plants that are grown in CO₂-rich environments can better tolerate environmental stressors like heat. CO₂ adjusts the internal water balance and reduces the need for the stomata to open excessively. As a result, it reduces water loss in transpiration and is less affected by high temperature or drought.

7. Use Resources More Efficiently

Cannabis plants might better use water and nutrients due to increased CO₂. Better metabolic efficiency effectively ensures that a smaller fraction of available resources is wasted, thereby maximizing returns on fertilizer and water investments. 

Cons of Adding More CO₂ to Cannabis

Increasing CO₂ has its drawbacks, too. In small grow spaces, CO₂ supplementation isn’t very practical or cost-effective. CO₂ levels must be carefully managed because too much can be dangerous for humans; installing a safety system to alert you to high levels is essential. 

You’ll also need to keep CO₂ tanks filled, which means regular upkeep. Finally, because plants may need varying CO₂ levels at different stages, determining the ideal CO₂ level for your plants’ needs can be tricky.

Ultimately, using CO₂ can be like plant steroids — effective when used correctly, but potentially overwhelming if overdone. By carefully managing CO₂ and light, you can create an optimal growth environment that’s safe, productive, and ready for an impressive harvest. Here are some more cons of adding excess CO₂ to cannabis plants: 

1. Increased Costs for Equipment and Maintenance

Setting up a CO₂ enrichment system involves buying tanks, generators, regulators, and monitors. Also, running costs include the continual topping up of the tanks and the energy used for the ventilating and lighting systems.

2. Risk of Overexposure

Excessive CO₂ concentrations hinder the ability of cannabis plants to absorb gases like oxygen when levels rise above 1,500-2,000 ppm. When you see such problems in the grow tent, beware that your plants can suffer from various issues like stunted growth, damage to the leaves, and reduced yields. In addition, you can also suffer from dizziness, headaches, or even suffocate if CO₂ goes up very high. 

To prevent this, use a high-quality CO₂ monitor and controller that keeps levels ranging between 1,200–1,500 ppm. Growers should allow good ventilation in the grow room so that there is no CO₂ build-up and install alarms that alert you of dangerous concentrations.

3. Complex Monitoring and Adjustments

As a grower, you need to monitor many other parameters along with the humidity, temperature, and light intensity along with the CO₂ levels for better yields. 

When any of these variables are out of balance, CO₂ will not only be beneficial but it may also damage the plants. 

Use integrated grow systems that will monitor and adjust the environmental parameters to automate as much as possible. You should calibrate the equipment regularly. Also, keep a continuous log of calibration readings so you can add or adjust more corrective actions.

4. Not Very Effective in Bad Conditions

Enrichment of CO₂ works well only in controlled situations. If light intensity, temperature, and nutrient availability cannot be optimized, additional CO₂ will not enhance growth materially. For instance, the plant’s ability to conduct proper photosynthesis is already low in conditions with less light, so the extra CO₂ is wasted.

Before you use CO₂, make sure the light is strong enough for plants to be healthy (for example 700-1000 μmol/m²/s) and maintain about 70-85°F while making sure that the nutrients are in the right range. 

5. Increased Heat Output

CO₂ generators, especially those that ignite natural gas or propane, produce heat as a byproduct. As a consequence, the grow room may get hotter, requiring higher-capacity cooling systems to cool it down. When plants are left to overheat, it can stress them to the point where CO₂ enrichment is ineffective. 

To prevent this, pay more attention to ventilation so that there's less heat build-up. Also, use reflective materials to distribute light in a uniform fashion and reduce hot spots. 

6. Possibility of Mold and Pest Problems

Conditions that utilize CO₂ usually require more heat and humidity to be efficient. They can create the perfect breeding ground for mold, mildew, and other pests like spider mites that thrive in warm, humid conditions.

Use a hygrometer regularly to monitor the humidity level and maintain it within safe levels (50-70%) depending on the stage of growth. Make sure the place is well-ventilated with fans and dehumidifiers. 

7. Environmental Impact

By growing cannabis indoors, you're already increasing the heat around you and creating a negative impact on the environment. Adding extra CO₂ on top of that might add to the carbon footprint of a grow operation – especially if that CO₂ is drawn from non-renewable methods like burning propane or natural gas. This is a cause of concern, whether you're conscious of the environment or not. 

8. Regulatory and Safety Concerns

Certain locations may have tight restrictions on how CO₂ can be stored and used, especially in large amounts. Also, using CO₂ may add to the expenditure and complication because of the permits, inspections, and more.

Know the local laws before using CO₂ systems. Buy equipment as per regulations and make good safety provisions such as exhaust fans, CO₂ alarms, and storage lockers. In addition, document compliance initiatives to ensure seamless audits and investigations.

How Much CO₂ Should You Use?

So, how much CO₂ do you need to add to see the results? For reference, in nature, the air already has around 400 to 410 parts per million (ppm) of CO₂ — plenty for a typical cannabis plant to grow. 

So, if a little CO₂ is good, is a lot better? Research shows that plants continue to grow at higher CO₂ levels, even up to 10,000 ppm. But don’t go cranking it up that high — anything over 3,000 ppm is hazardous to breathe, and CO₂ levels above 5,000 ppm can be lethal. 

For safe and effective cannabis growth, aim to keep the CO₂ in your grow room between 1,200 and 2,000 ppm. Even around 1,500 ppm can boost growth by up to 30%, giving you bigger, healthier plants! Anything more is overkill and asking for trouble. 

The CO₂ concentration must be regulated in accordance with the growth phase of the plant so that you maximize the benefits and there's no wastage or harmful effects. 

Seedling Stage (400–500 ppm)

Cannabis plants at the seedling stage are in their earliest and most delicate stage of development. Given their leaves' small size and immaturity, they have little capacity to photosynthesize so they don’t need high CO₂ levels for their growth. Also, since the surface area of the leaves is really small, it limits the absorption of CO₂ and also reduces the rate of photosynthesis. At this point, increasing CO₂ above ambient levels is a waste and harmful.

In addition, the seedlings are still growing roots. Stress from environmental factors may slow down root growth. High levels of CO₂ might disturb the balance of oxygen available to seedlings for root respiration, which can affect their growth.

If a plant gets too much CO₂ at this stage, it can interfere with the plant’s gas-exchange processes, creating stress rather than growth. In short, adding more CO₂ during the seedling stage will only invite unnecessary extra costs with no improvement in crop productivity. 

Instead of adding extra CO₂, it’s best to optimize the CO₂ that’s already present in the grow room by adding more fans. However, make sure the fans aren’t pointing directly at these delicate darlings as their stems aren’t yet strong enough to handle force. 

Vegetative Stage (800–1,200 ppm)

In the vegetative stage, cannabis plants focus on building a solid stem, leaves, and root structure to prepare for flowering. During this phase, photosynthetic activity along with energy production and growth will rise quickly. As a result, the plant will need more CO₂. Thus, increasing CO₂ beyond ambient levels (400 ppm) may strongly enhance vegetative growth through the plant’s internal ability to convert light to useful energy.

Remember that plants grow faster because they can use carbon dioxide in the air more easily. And because of that, they can build stems and leaves faster.

Inevitably, they produce bigger leaves that help capture more light. Higher levels of CO₂ help the stems and branches to grow thick and strong, helping the plant support buds at a later stage. More photosynthesis means more energy which means the plant can also develop stronger roots.

And, thanks to more CO₂, the plants also will utilize nutrients more efficiently, improving overall health and vigor.

To provide optimal CO₂ concentrations, start with approximately 800 ppm when plants first begin the vegetative stage. Increase the CO₂ gradually to avoid overwhelming young plants and let them adjust to high CO₂. As the size of the plants increases, their capacity to use CO₂ also increases. Ultimately, 1,200 ppm is good enough for mature vegetative plants, if you’re able to supply sufficient light and nutrients. 

Remember, CO₂ enrichment will not work unless light intensity is adequate. So, 600 μmol/m²/s light is recommended for photosynthesis in 800–1,200 ppm CO₂.  

If you’re using LED lights, make sure it’s full-spectrum and are adjustable intensively.

In addition, you must keep the environment balanced. Make sure the temperature is within 75°F - 84°F (24°C-29°C) degrees under conditions rich in CO₂. As the temperatures rise, metabolism speeds up because of an increase inCO₂ as well. 

Finally, keep relative humidity in the 50-70 % range to prevent water stress and keep photosynthesis efficient.

Flowering Stage (1,000-1,500 ppm)

For cannabis growers, the flowering stage is the most crucial phase of growth as the buds will start to form and mature and develop potency and aroma. By adding CO₂ to the air during this stage, you can substantially improve bud size, density, and resin production. Higher levels of CO₂ in the atmosphere allow the plant to photosynthesize more as the plant needs a lot of energy when it's developing flowers.  

But, why is CO₂ extra important during flowering, you ask? Well, more carbon dioxide means more sugars and energy, which causes the buds to become bigger and heavier. Plants that are grown with enriched CO₂ often have more trichomes, improving the potency and resin production.

Higher levels of CO₂ cause flowers to form more densely, making them yield better. Under favorable CO₂ levels, plants can have a slightly faster flowering cycle for quicker harvests.

In stressed conditions, the increased flowering temperature of cannabis and higher light levels with increased CO₂ enhance overall productivity. In addition, the plants can also cope with higher flowering temperatures (85–88°F or 29–31°C) and higher light levels.

You can start at 1000 ppm as you move off of veg and increase to 1500 ppm as flowers develop.

Apart from CO₂ during flowering, make sure you provide lots of light ranging from 800 to 1,000 µmol/m²/s. Plants can't use more CO₂ without sufficient light.

Next, keep the temperatures between 75°F to 85°F (24°C to 29°C) and relative humidity should remain between 40-50% during flowering to prevent mold, and mildew and to maximize photosynthesis. 

Increased photosynthesis and growth rates call for a higher nutrient supply as well. Keep an eye out for a lack of phosphorus and potassium as this can hamper the flowering.

Other than that, make use of oscillating fans to uniformly diffuse CO₂ around the cultivation area. Stagnant air creates pockets of uneven CO₂ along with wasted resources.

Finally lower CO₂ to ambient levels (400–500 ppm) in the final weeks. It helps the plant concentrate its energy on ripening buds and increasing terpenes and cannabinoid production instead of continuing to grow. Excess CO₂ during the fag end of flowering will reduce terpene production as the plant will focus more on the growth rather than its chemical composition.

How to Add CO₂ to Your Grow Room?

Adding more CO₂ to your grow room can either be tricky and expensive or straightforward and cheap, depending on the method you use. Here are the most popular ones. 

• CO₂ Generators

CO₂ generators, often called CO₂ burners, look a bit like patio heaters. These devices burn propane or natural gas to create carbon dioxide and are the go-to for larger grow rooms. 

With built-in power switches and valves, CO₂ generators can automatically regulate the CO₂ output to a precise ppm level for your plants. However, since they burn gas, they tend to raise the temperature by about 5 degrees F and humidity by roughly 7%.

To handle this, you can try adding an air conditioner. Plus, you should consider adding good ventilation or dehumidifiers to avoid overly humid conditions. Finally, make sure to buy your CO₂ generator from a reliable retailer for the best results and safe operation.

• Compressed CO₂

For smaller grow rooms, compressed CO₂ is an ideal choice. Since compressed CO₂ doesn’t produce heat, humidity, or sulfur, it’s perfect for smaller spaces. You can find these cylinders at hydroponic stores, home brewing shops, or compressed gas facilities, usually ranging from 20 to 100 pounds, with one pound equaling about 8.5 cubic feet of CO₂ gas.

To release CO₂ from these cylinders, you’ll need a setup that includes a pressure regulator (to lower tank pressure to about 5 psi), a flow meter (to adjust the CO₂ flow), and a solenoid valve with a timer to control the release automatically. 

You should also use tubing with tiny holes spaced about a foot apart for even CO₂ distribution. While more complex than other methods, compressed CO₂ gives you precision without affecting your grow room’s environment.

• Dry Ice

Dry ice offers one of the simplest and quickest ways to boost CO₂ levels in your grow room. Just place a block of dry ice, which is essentially frozen CO₂, near your plants, and as it melts, it will slowly release CO₂ into the surrounding air. 

This method requires no complicated setup or special equipment, making it ideal for growers looking for a low-fuss solution. You can also adjust the amount of CO₂ by controlling how much dry ice you use at a time, making it adaptable to your grow room’s needs. 

• Compost

If you’re looking for an all-natural CO₂ solution, placing a compost bag near your plants is an effective and eco-friendly option. As the organic material in the compost decomposes, it releases CO₂ slowly and steadily over a period of up to three months. 

This method is both affordable and sustainable, offering a natural alternative for increasing CO₂ levels without complex installations. However, compost doesn't allow for precise CO₂ control, and you won’t be able to shut it off once it’s in motion. 

Common Mistakes to Avoid When Introducing CO₂ to the Grow Room

With proper CO₂ enrichment, you can greatly enhance the growth and yield of your cannabis, but mistakes can minimize its benefits or even harm your plants. Here are a few things you should keep in mind:

1. Misjudging CO₂ Levels or Timing

Using the wrong CO₂ concentration at the wrong stage of growth can harm your plants instead of helping them grow and yield more. 

For example, seedlings cannot use extra CO₂ and may suffer from stress. Also, extra CO₂ at the very end of the flowering cycle will also slow down the production of cannabinoids and terpenes. 

Coming to the levels of CO₂, adding too much can do more harm than good. Not only will the plants show signs of stress but the resources you're providing to the plants will also be wasted. 

2. Ignoring Ventilation Needs

If you seal up your grow space too tightly to retain CO₂, you will not have enough circulation. Remember, plants need oxygen too to respire, even at night. 

Also, bad air circulation can cause stagnant zones that reduce CO₂ distribution and may lead to uneven growth, not to mention that stale air can cause mold, pests, and other problems.

To guarantee evenly distributed CO₂ in your growing space, the solution is to use oscillating fans. Also, install an exhaust system to regularly exchange stale air without removing all that CO₂. 

Finally, keep an eye on the oxygen levels during dark hours so that your plants do not stress out.

3. Not paying attention to light intensity 

Providing more CO₂ without increasing light intensity, temperature, or nutrients to increase a plant’s metabolism is another mistake that's common among newbies. 

The fact is that high levels of CO₂ can only enhance photosynthesis with sufficient light energy. Any additional CO₂ will go to waste without proper lighting. If you don't take care of the lighting, there will be deficiency and poor growth.

Thus, make sure that light intensity matches CO₂ levels and that the environmental factors are perfect for the plants. Increase feeding to match the plant’s increased growth but keep an eye on nutrition and nutrient toxicity.

4. Overlooking Safety Precautions

Excessive CO₂ levels can be dangerous and lead to various problems including headaches, dizziness, and other more serious symptoms.

You should install CO₂ monitors with alarms to warn you if the CO₂ level gets too high. Yes, you should take care of the plants, but be cautious about your own safety too! 

Should You Use CO₂ to Grow Cannabis?

Let’s answer the most important question, should you use carbon dioxide to grow cannabis, though? After all, just because you can do something doesn’t mean you should, right? Well, the answer isn’t so simple and it depends on a few things. 

While adding CO₂ can definitely boost plant size, it's not always the best route. Using CO₂ systems comes with benefits, but they’re expensive and require precision. If you’re a newer grower, this process may be a bit much at first.

If you’re just starting out or working with a tight budget, there are other yield-boosting methods that are simpler and less costly. Before investing in CO₂, try these alternatives to get larger plants without breaking the bank.

Here’s a quick checklist to know if you’re ready for CO₂:

• You’ve grown healthy plants with dense, potent buds
• You’re skilled at handling pests and mold on your plants
• You’re using strong lighting, the right nutrients, and quality grow mediums
• You’re working with proven cannabis strains
• Your grow room is sealed from the outside air
• You’ve budgeted for a CO₂ system

If you can check all these boxes, you’re likely prepared to use CO₂ for cannabis yields. Keep in mind that CO₂ systems are complex; even a minor misstep can affect your plants — or even you. Also, be aware that CO₂-enriched plants might need more nutrients to reach their full potential.

Summary: Does Carbon Dioxide Increase Cannabis Yield?

CO₂ supplementation can indeed help your cannabis plant reach new heights, but it’s a technique best suited for experienced growers ready for an investment in both time and equipment. 

If you check all the boxes — solid growth history, proper lighting, sealed room, and a flexible budget — adding CO₂ could be worth it. Just remember, CO₂ can supercharge growth only when it’s paired with the right setup. Otherwise, stick with simpler techniques and grow your plants within your current resources.