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Why do Cannabis Plants Need CO2?
Like all other green plants, cannabis transforms light energy into chemical energy through a process called photosynthesis. Chlorophyll-containing organelles known as chloroplasts convert CO2, water, and minerals into organic compounds that are rich in chemical energy plants use to grow.
Fortunately for us, oxygen is a by-product of the process. It is released by the plants during the day as they absorb CO2. The gases are released and absorbed via the plants’ stomata, which are minute openings surrounded by guard cells on the undersides of their leaves.
If a cannabis plant does not get enough CO2 they will continue to grow until their stored sugars are depleted. Once that happens, their metabolism decreases, and they show little to no signs of growth.
On the other hand, if a plant gets too much CO2 it will slow down or even stop photosynthesis. The trick is finding the right gas level for a grow space to speed up photosynthesis and lead to abundant growth and boosted yields.
When to use CO2 in your grow room?
Many growers often ask themselves, when is the right time to introduce carbon dioxide in an indoor grow environment. And, the answer is quite simple.
For those that are looking to add carbon dioxide to their grow room, the flowering stage is said to be the most important. It is critical that when you supplement CO2 to your crops you do so within the first 2-5 weeks of flowering which will spearhead your crop production and boost overall crop size upwards of 20-25%.
Best way of adding CO2 to grow tent
Carbon dioxide gas is necessary to support life. People breath in oxygen and exhale CO2. Plants take in CO2 and put out oxygen. Without this oxygen and carbon dioxide cycle there would be no life on earth as we know it.
While CO2 concentrations greater than 3% are dangerous to human health, that level is almost never found in nature, and is much more than the amount cannabis plants need to grow. To put it in perspective, CO2 makes up about 0.04% or 400 ppm of the earth’s atmosphere. Double that in an enclosed greenhouse and you’ll get sleepy, but your plants will thrive.
That being said, the best way many growers add CO2 to their grow room, is by hanging slow-release CO2 bags or bottles. In doing so, carbon dioxide will then be dispersed slowly overtime and can also be extrapolated to larger growing areas. A rule of thumb for an enclosed space is one co2 bag per 4×4 area or per 4×4 grow tent.
For those with more large-scale operations, you can choose a CO2 gas tank or CO2 generators in order to automate delivery and send the CO2 gas down through pipes for an uninterrupted supply to your crops.
How Much CO2 Is Enough?
The optimal amount of CO2 required to boost the yield of cannabis plants depends on several factors including the intensity of the light and the size of the grow space. In an indoor space with normal ventilation, the concentrations of CO2 should be around 400ppm, which leads to growth rates like what you would expect if you were growing your plants outdoors.
Growers have achieved the best success with CO2 levels between 1,200ppm and 1,500ppm. However, you cannot simply increase the CO2 level unless your plants can use it.
CO2 and Light
If you are growing your cannabis plants under low light (around 12,330 lux/1150 fc), you can increase their photosynthesis by maintaining CO2 levels at 400ppm. For additional growth you will need to increase the intensity of your grow lights.
Increasing the light intensity to somewhere around 49,310 lux/4600 fc allows you to increase the CO2 level and therefore, plant growth. The rate of photosynthesis will speed up as you raise the CO2 level to 600ppm. Beyond that, the rate will increase more slowly. You can increase the level to as much as 1200ppm under that lighting, although photosynthesis will be even slower.
If you can increase the light intensity to 59,201 lux/5500 fc, your cannabis plants can use increased CO2 levels of between 1200 and 1300ppm. You could increase the level to 1500 ppm if your light intensity increases to 80,400 lux/7500 fc. Growers who have taken it to that level recorded a 100% increase in their plants’ growth rate.
Calculating the Amount of CO2 Required
As tempting as it may be to rush out, purchase a tank of CO2 and empty it into your cannabis grow space, that would probably be the worst thing you could do for yourself and your plants. First, you should always use a simple calculation to work out how much CO2 your space needs.
Let’s say you want to increase the level of the gas to 1,000ppm. To work out how much you need, multiply the room’s cubic area (length x width x height) by 0.001. The result is the number of square meters of CO2 you need.
For example, a room that is 4m long, 4m wide, and 3m high has a cubic area of 48 cubic meters (4 x 4 x 3 = 48). Multiply 48 by 0.001, and the result is 0.048 cubic meters. In other words, it only takes this small volume of CO2 to raise the level to 1,000ppm.
For further resources, check out our “CO2 Calculator for Grow Room or Indoor Greenhouse Guide“.
Best CO2 system for your grow room
As discussed, there are various ways in which you can increase the CO2 level in your cannabis grow space. With CO2 kits and systems, you can use these to inject and monitor carbon dioxide into a grow room or greenhouse to encourage faster plant growth. In addition, the average level of Carbon Dioxide in the atmosphere is about 300 ppm. By increasing the ambient CO2 levels to 1500 ppm, CO2 enrichment systems greatly enhance the growth rate of plants.
The basic equipment you will need in any CO2 system set-up is the right CO2 meter such as the Carbon Dioxide Handheld Gas Detector or a Day Night CO2 Monitor & Controller for Greenhouses, in order to monitor the ambient CO2 levels in your grow space.
Assuming you get the basics, you would measure the amount of CO2 in the atmosphere, release CO2 from the tank using the regulator and valve, and then take another measurement. If you have the funds, you can purchase the equipment for a more elaborate set-up that can streamline the process, or that can help make it safer for you and your cannabis plants.
As a reminder, it is also important to note within any indoor grow space setup that when using carbon dioxide and working around CO2, although it is beneficial for plants – it is hazardous for humans and overexposure to CO2 can occur. You should always ensure proper CO2 safety detection as well, for indoor grow spaces.
Best CO2 monitor for your grow room
When it comes to best CO2 monitoring devices for your grow room, CO2Meter specializes in a plethora of carbon dioxide solutions dependent upon your indoor grow space, requirements, and production set-up.
Below are just a few of our top CO2 monitors, controllers, and sensors for indoor agriculture, greenhouses, grow rooms, or hydroponic shops.
- CO2 Multi Sensor System (CM-7000)
- Remote CO2 Storage Safety 3 Alarm (RAD-0102-6)
- Personal 5% CO2 Safety Monitor and Data Logger (SAN-10)
- Day/Night CO2 Monitor and Controller for Greenhouses (RAD-0501)
- *Coming Soon!* CO2 Grow Controller for Grow Rooms (RAD-0502)
- Carbon Dioxide (CO2) Handheld Detector (CM-501)
Where should CO2 monitors be placed?
In any indoor agriculture application or greenhouse, rule of thumb is when installing a CO2 safety device you should place your device 12-18 inches from the lowest point of the room. When you are utilizing a CO2 controller, the sensor should be placed at canopy level and the display should be placed at eye level.
Using CO2 safely and correctly in your grow space may be the final step you need to take for a healthy crop. If you are not achieving the right levels of CO2, you may well be missing out on the best possible yield.
See the below for more tips, guides, and resources for your grow space:
- DrCannabis.Io
- Indoor Agriculture CO2 monitors and controllers
- Indoor Agriculture Grow Facility and CO2 Solutions
- CO2 Meters Improve Indoor Gardening
For more information on CO2Meter.com sensing technologies or indoor air quality devices, please contact us at [email protected] or (877) 678 – 4259
Director of Marketing, CO2Meter.com