Growing the best cannabis buds is a balancing act. From nutrients and water to light and humidity, cultivators must constantly monitor multiple grow space specs.
One crucial consideration that some cultivators overlook is ambient CO2. True, increasing CO2 isn’t as “necessary” as other metrics. However, considering how much CO2 generators could increase yield, they could be the key to supercharging a commercial cultivator’s ROI.
CO2 for plants is the “breath of life.” Growers who fail to account for CO2 levels in proportion to light, heat, and humidity cannot produce high-quality cannabis. However, those who take the time to increase ambient CO2 will be rewarded with fast-flowering strains.
The mechanisms of CO2 absorption may be complex, but new research suggests cannabis has a well-defined “CO2 zone” that produces phenomenal results. Commercial cultivators should have a basic understanding of what CO2 does and how they could manipulate it to their advantage.
Why Does Cannabis Need CO2?
Even if you’re not a horticulturist, you’ve probably heard the term “photosynthesis” before. This natural phenomenon is central to any green plant’s growth cycle.
CO2 is one of the primary chemicals cannabis draws in during photosynthesis. However, marijuana strains also convert light energy and water into sugars throughout vegetation and flowering. During this complex conversion process, cannabis plants grow sturdy stems and green foliage while giving off oxygen.
Without enough CO2 in the air, cannabis plants can’t grow healthy and strong—which leads us to the following consideration: Just how much CO2 is necessary?
How Much CO2 Is Good For Cannabis?
There are still debates over how much CO2 cannabis needs to thrive, but most reports suggest 800 – 1050 parts per million (ppm) is ideal. Master growers often keep these levels closer to 800-1500 ppm during vegetation and bump them up once flowering starts.
Please remember that plants can’t absorb CO2 without light. So, even if you run a CO2 machine at full blast overnight, it won’t do your plants any good! Please only turn your CO2 burners on during the day when there’s plenty of light in your grow space.
Just how much light you’ll need depends on your grow room’s CO2 levels. For instance, CO2 concentrations between 800 ppm and 1,500 ppm should have a light intensity of at least 1,000 µmol/m2/s. Typically, this combination leads to a 10 – 25 percent increase in total yield and a faster growth rate.
For those who bump up their CO2 to the 1,000 ppm – 1,200 ppm range, it’s best to increase light penetration to between 1,200 µmol/m2/s – 1,500 µmol/m2/s. You should also keep the light intensity at 1,500 µmol/m2/s if you’re using anything above 1,500 ppm of CO2.
Just keep in mind that most cannabis cultivators suggest anything above the 1,050 ppm level won’t lead to a noticeable improvement in growth size or speed. Indeed, as you near 1,800 ppm of CO2, your plants could die. If you mistakenly raised your CO2 to 4,000 ppm, then you’ve reached the toxic level for humans.
On the opposite extreme, anything below 200 ppm of CO2 will cause cannabis plants to die. While the average outdoor range of 400 ppm won’t kill cannabis, it won’t yield the most robust crop.
In general, there is a 1:1 correspondence between CO2 saturation and photosynthetic photon intensity distribution (PPID). In other words, 1µmol/m2/s of photon absorption by plants requires 1 PPM of CO2 to achieve a maximum growth rate. But too much or too little carbon dioxide won’t do.
As a final note: Please don’t forget you’ll need to adjust heat and humidity as you increase CO2 levels. Cannabis plants have an easier time absorbing CO2 at higher temps, which means you’ll need to spend more time and money adjusting your grow room’s heat settings. Generally, the ideal temperature range for CO2 absorption is between 75° F and 80° F.
|<200ppm||Plant Growth Ceases|
|200~350ppm||Plant Grows Slowly|
|300~410ppm||Ambient CO2 Saturation||CO2 saturation for most outdoor cultivation|
|800~1050ppm||Increase Growth Speed; Increase Yield Around 10%||Require light PPFD at 800-1200 umol/m2/s|
|1000~1500ppm||Optimal Saturation For Cannabis||Require light PPFD at 1200-1600 umol/m2/s; Grow Room Operation Temperature can reach a maximum of 36 ℃|
|1500~2000ppm||Growth Speed Can Still Be Increased, But Hard To Control||Require light PPFD at 1600-2000 umol/m2/s;|
|>2000ppm||Harmful To Both Plants And Humans||Reduced economic benefits of increasing CO2|
|10000ppm||Deadly For Living Things||Can be used to kill insects such as spider mites|
What To Pay Attention To When Adding CO2
Cultivators who want to add CO2 should never forget this compound could only have a beneficial effect if it’s well-calibrated with a room’s light, heat, and humidity. Not only that, extra CO2 will affect your room’s relative humidity by increasing the rate of oxygen exchange.
Higher humidity levels can increase the risk of mold, so CO2 cultivators need to have a ventilation strategy in place before adding CO2 units. HID growers should also seriously consider switching to LED grow lights, as the latter won’t give off nearly as much ambient heat.
Regarding heat, cultivators should know that CO2 generators will increase the temperature of their grow space. Sometimes called “CO2 burners,” these generators release CO2 into the atmosphere by “burning” a fuel source like propane. While this could be a positive for folks in cold climates, it makes CO2 generators a no-go for greenhouses in temperate zones.
While CO2 generators cost more upfront, they tend to save big commercial operations in the long run. These units also do a fantastic job distributing CO2 in large spaces, especially if they’re hanging above your plants.
By contrast, compressed CO2 tanks are ideal for smaller grow set-ups because they’re convenient for moving in and out of your space. These tanks are similar to more common propane tanks, but they’re filled with CO2. Growers strategically place their compressed CO2 near an oscillating fan whenever they want to distribute CO2 to their plants.
Mars Hydro LEDs Are A Must For CO2 Cultivation
If you’re going to spend the extra time and money to add CO2 to your grow set-up, you can’t settle for inferior quality grow lights. Only grow lights that give off a high PPFD score of 1000-1500 μmol/m²/s can supply your plants with the adequate and necessary “food” for optimal photosynthesis. And, precisely because these lights are needed to emit intense light, you need them to be able to be distributed evenly enough to avoid burns or inadequate corner light exposure.
Regarding these, Mars Hydro’s engineers specifically designed the FC8000 and FC-E8000 to work in conjunction with a CO2 system. Not only do the two models give off a just right PPFD score of 1100-1600 μmol/m²/s at every point, they can be hung lower to penetrate more light down to stems in the depths.
To learn more about how the Mars Hydro FC8000/FC-E8000 could enrich your CO2-enhanced space, check out this link.