You've been in the cultivation game for a while, but you hold yourself to the principle of "kaizen" or continuous improvement.
So now what?
Now, it's time to look towards altering the CO2 levels in your grow. By supplementing carbon dioxide, you're allowing your plants to use all available light in the room.
With the added boost, you'll see healthier plants, faster growth cycles, and higher yields. This means that you can flip rooms faster while getting more product from your work.
Keep reading to find out 9 tips for increasing yield with CO2 supplementation.
1. A Refresher On the Role of Carbon Dioxide
To understand why you need to supplement CO2 in your indoor grow, you have to first remember the process of photosynthesis.
With a light source, water from the soil, and carbon dioxide from the environment, plants create their energy and output excess oxygen. Growers tend to focus on only two of these elements, but CO2 is just as important for plant growth.
In an outdoor setting, plants can continually eat up CO2 from an endless supply. Indoor plants are a different story.
Once they've consumed the CO2 available, its levels are decreased, leading to less photosynthesis. If you have fresh air exchange (FAE) in your room, the standard environmental CO2 levels are replenished.
But is that enough CO2 for a healthy crop? They won't die if it has normal environmental CO2 levels, but working with that amount is similar to only using 13 hours of light during your veg cycle.
It's not as efficient or optimal.
2. Use a Carbon Meter
Carbon meters use infrared radiation to detect the parts per million (ppm) of CO2 in the air.
For a baseline, the earth's atmosphere currently contains 418 ppm of CO2, making up .04% of the total air composition. If you don't supplement your plants with CO2, you're setting them up with the same air that they would have outdoors.
That results in the same level of photosynthesis as you'd have outdoors, wasting your extra light input.
The ideal level of CO2 for indoor cannabis is between 1200 and 2000 ppm. You can figure out your current standing by purchasing a carbon meter to see the necessity of carbon dioxide supplementation.
During this type of discussion, people tend to mention human health hazards when working with CO2. While it's true that excess CO2 can harm people, data shows that negative effects aren't seen until you get above 30,000 ppm.
3. Know the Restrictions to Increasing Yield with CO2
When supplementing with CO2, you should have every other element of your grow dialed in. This includes lighting, water, nutrient schedules, pest control, temperature, and humidity.
The only way that you'll see benefits from supplementation is if these other factors are where they need to be. In other words, CO2 should be your only "limiting factor" or uncontrolled variable that you're not regulating yet.
This is why CO2 supplementation is left to experienced growers.
Additionally, you'll want to make sure that your growing space is completely sealed. Otherwise, you will passively lose the CO2 that you're spending money on.
4. Work Within Your Means
When researching CO2 supplementation methods, keep in mind that it's not a one-size-fits-all scenario.
The solution that's going to boost your grow depends on the money you have available, the size of your space, and the current equipment you're using.
For example, supplementation only makes sense if your light sources are HPS or high-output LEDs.
Keep in mind both the initial equipment investment (i.e. CO2 source, tubing, etc) as well as the recurring expenses (i.e. compressed CO2 refills, propane, etc). You'll want to budget for an entire grow cycle so that you have time to measure whether supplementation is worth it to you.
5. Choose Viable Supplementation Methods
If you know that not all nutrients are created equally, then you can assume the same with CO2 supplementation methods.
The two primary options are a CO2 generator or a compressed CO2 tank. Both can be modified to have sensors, timers, and valves, making them fully automated.
CO2 generators burn propane or natural gas to create a carbon dioxide output. They're best for large spaces, as they have a higher output than tanks. They also have significant heat and water vapor output, which is more challenging to regulate in a small space.
If you use a CO2 generator, be sure to buy a carbon monoxide detector to keep your operation safe. It's a bigger initial investment than compressed CO2 but it doesn't cost much once you get everything set up.
Compressed CO2 tanks simply release carbon dioxide without any heat or water vapor. You can refill the tank easily, making it a sound choice for smaller cannabis grows.
Online, you'll see that there are alternative methods to increasing CO2. This includes using compost, fermentation, or mycelium bags. These processes have little effect and also introduce more microorganisms into your space, which isn't ideal.
6. Placement is Key
CO2 is 1.383 times heavier than oxygen, as it has the added carbon molecule. As a result, carbon dioxide will sink lower than oxygen in a still environment.
There are two ways to combat this so that your plants can breathe in the added CO2.
First, you should set up your air tubes with even holes above the plant canopy. This allows the CO2 to "fall" around your cannabis.
If you don't already use them, you should also add oscillating fans to your setup. This helps stir up the air so that the CO2 reaches more plants. Leaves soak up CO2 quickly, so moving the gas around with fans helps to distribute it as much as possible before it's soaked up.
In a pinch, you could also put fans on the floor pointing up.
Another placement consideration is whether you have exhaust fans. If you do, you'll want to rearrange your system so that you're not shooting the supplemented CO2 straight out of the grow room.
7. When to Use CO2
CO2 is only effective when you have high amounts of light, heat, and humidity.
In terms of light, it's best to use CO2 supplementation when you have your plants on an 18/6 light cycle. If you were to supplement with low levels of light, you're just wasting CO2.
The ideal heat range for CO2 absorption is between 85 and 95F degrees. This is a little bit outside of the typical recommendation for vegetative plants and a few degrees warmer than what's needed for flowering.
While CO2 increases your plants' heat tolerance, you can get away with keeping the environment around 85F. You don't need to increase the heat in your space to go any higher than this.
Finally, the relative humidity should be between 70-75%.
With these factors in mind, you can supplement with CO2 in your plants' vegetative phase through mid-flower. Once you're mid-bloom, you'll want lower humidity, making CO2 supplementation less effective.
To keep things cost-effective, people often choose between supplementing during veg or flower. The jury is still out on which application is best, so you'll have to try each and see for yourself.
You never need to supplement CO2 to seedlings or clones in incubators. At this phase, they're only focusing on developing healthy roots.
8. Create a Balanced System
You learned where a few environmental factors need to be to benefit from CO2 supplementation.
You should also keep in mind the changes in nutrient and water needs during the process. You're changing a main component of your grow and may need to make adjustments due to booming plant growth.
In terms of integrating CO2 supplementation into your automated processes, you should look towards your light cycle to guide your CO2 cycle. Plants don't take in carbon dioxide during the night, so that's the time to turn your generator or tank off.
Plants release some CO2 at night as they're no longer metabolizing energy. Because of this, you can wait until around an hour after you "wake up" your plants to kick on your CO2 machine.
To simplify, you should have an automated cycle starting 1 hour after "waking up" and ending 1 hour before "going to sleep". Your machine will kick on and off through this period to dose out CO2.
9. Take Notes and Make Adjustments
To make sure your investment pays off, you should try to keep notes on how much CO2 you're using, the speed of cannabis growth, and yield weights.
It helps to start with a "control" round without CO2 so that you have the baseline numbers for comparison. If you're not much for recording data, you can see through experience whether there's a visible difference.
Aside from increased yields and faster growth, you may notice darker, thicker leaves and healthier plants.
Keep Growing Cannabis at the Highest Quality
With these 9 tips for increasing yield with CO2 supplementation, you can achieve a continual state of improvement while producing the best flower possible.
Keep reading our blog for more growing tips.
