Of all the technologies and methods that exist to improve and prolong plant production, the incorporation of CO2 is probably the fastest, simplest and simplest of them in the cultivation of marijuana. Each species has maximum levels of CO2 that it can absorb, but depending on the species and with the necessary CO2 contribution, the growth increase can be up to 40%.
Two concepts to exploit in the cultivation of marijuana
It is essential for everyone to know what we are talking about at all times. For this reason, to avoid confusion in the rest of the text, it is convenient to clarify some concepts:
- Air renewal : We refer to air renewal when we change the air in the cabin for a new one, that is, we remove the old air and change it to fresh air.
- Air recirculation : We remove the same air that is in the passenger compartment, so that it is in motion, using fans.
Why does CO2 help?
Photosynthesis is the process by which plants inhale CO2 from the air and combine it with water, and using the energy of light, produce sugars and oxygen. Plants cannot move to seek new air, so the air has to be renewed periodically so that the plant does not stop the production process of the sugars necessary to grow. When we renew the air, CO2 is added in large quantities and the plant will respond with vigorous growth. Therefore, it is vital both a good air exchange through intake / exhaust, as well as a good interior ventilation.
CO2 deficiency
Many beginners make the mistake of not thinking about the importance of CO2 in a closed area. In a growth room, plants quickly consume CO2 and convert it into oxygen. When the plants have absorbed one third of this CO2, growth will be quickly hampered, and the plant will stop growing. The situation is more serious in areas without any type of air recirculation , because the plants create a microclimate around the leaves. This small area is emptied of CO2 very quickly due to the direct contact of the leaves with it. If we recirculate the air constantly, we will avoid the contact of the leaves with the air lacking CO2. Renewing CO2 is always necessary, even in a room with good recirculation . A closed room full of healthy plants can be depleted of CO2 in just an hour or so. Clones, cannabis seeds or small plants will not use as much CO2, but they still need a good renovation.
Measurement of CO2 content
CO2 is calculated and measured in parts per million (ppm). Air typically contains around 300ppm and city air up to 450ppm. Many researches place the level maximum ideal for lush growth around 1500 ppm , almost 5 times the amount of CO2 in air.
Before you begin
Before choosing a CO2 production system, keep in mind that CO2 is not the only important factor for good growth. If any of the factors are ignored, all your efforts with increasing CO2 will be in vain. The factors are: 1-.Ventilation 2-.Temperature 3-.Humidity
Ventilation
- Air circulation and ventilation: If we inject CO2 into a room without recirculation, the CO2 will fall at the foot of the room and stay there, since CO2 weighs. Even with moderate ventilation, the CO2 will not reach the leaves.
- The key to maintaining internal CO2 levels is circulation. Plants notice the benefits of the constant puff of CO2. Many growers use a double layer of circulation. A layer of ventilation at the height of the plants and another at the ground level to remove heavy CO2.
- Vertical air circulation: Moving the air vertically helps to remove CO2 and avoid weak points (microclimate) of the culture chamber. The cold air from the ground is moved towards the hot lamps, lowering the temperature, while at the same time raising the CO2 again.
- Air renewal and ventilation: Even when we supply CO2, ventilation is necessary to remove the stale air created by the plants, as well as the renewal to expel the excess oxygen created by them. It is convenient to alternate cycles well.
- Basic ventilation concepts : Assuming that CO2 is supplied through renewal, high speed and evacuation periodicity is desirable to make the air change as quickly as possible. If the CO2 is not renewed, it is useless to ventilate.
Temperature and humidity control
The use of climate measurement devices is necessary, both for temperature and humidity. The desired ranges are: 1- Temperature: the best range is between 19-24ºC. Some tests indicate that the best temperature for CO2 absorption is 24ºC with 1500ppm. Other experiments show that it should not drop below 18ºC. The ideal temperature will be in a medium term, around 22ºC. 2- Humidity: the ideal humidity is between 40% and 65% . With 65% humidity everything works, but problems can occur with higher humidity. Mushroom reproduction stops when humidity is low and constant. Some growers overlook that humidity rises during the dark period. Some growers run the fans only at the same time as the lights. This exacerbates mold growth during the night cycle. To prevent this, we must connect the fans also during the dark period . A dehumidifier will help lower the humidity and maintain the temperature. If the temperature plummets the relative humidity will rise. The same amount of water dissolved in cold air creates more moisture than when dissolved in hot air. A hygrostat connected to the dehumidifier can help us keep the humidity constant. The temperature and humidity controllers with maximum and minimum will help us to control the parameters during the dark period without having to enter the cabin and interrupt the photo period.
Temperature control
The heat created by high pressure lamps can be a problem for some growers. It is very difficult to keep the temperature between optimal values, especially in summer. There are several solutions to that problem. Some are simple but expensive, and others are ingenious and inexpensive. Here we will propose the most frequent ones:
- Installation of an air conditioner (AC)
- Installation of a cold reflector (Cooltube)
Air Conditioner Installing an air conditioner is one of the fastest ways to avoid problems. It's simple, place it in a window, turn off the fan position, and adjust the temperature. Some people will think about the cost that this represents, but you have to consider the benefits as well. The electric bill can really be a problem if the appliance has to be in operation for many hours. If so, it would be wise to consider isolating the cabin. Cold Reflectors Cold reflectors are usually a good choice for rooms with limited space, allowing the temperature to be reduced between 5-10ºC, although their refractive capacity is not as good as that of some professional reflectors. Humidity control Many growers use an electric dehumidifier to control humidity. With the dehumidifier everything is simple, you just have to set the hygrostat at the desired humidity and the dehumidifier will connect and dry the room when the humidity exceeds the desired parameters. Simple and inexpensive , although it will be expensive if you have to be connected all day. Although it is possible to think that we will also save water , since the dehumidifier will provide us with distilled water that we can use for growing, as long as we keep the filters of the device clean. However, there are several techniques that are usually used if you do not have a dehumidifier:
- Increase in the frequency of air renewal. Assuming that the exterior humidity is lower than that of our cabin, it is simple, you just have to renew the air more frequently, for, by glasses communicating to achieve the same humidity as outside.
- Increased ventilation frequency , or its power, ensuring that ventilation is complete throughout the cabin, and avoiding unwanted pockets of moisture, formed by poor air circulation. If the humidity is not the same and constant in all parts of the cabin, we will be able to observe different growth patterns due to the different microclimates that coexist due to poor air circulation.
- Try to take the incoming air from another place. The air inside the house, or the air that comes from a not sunny area, will tend to contain more water than the outside air that comes from from a sunny area. Although we must also take into account that indoor air contains a higher level of CO2, due to our own action, that of pets, or combustion. Air absorbed from low areas usually contains more moisture than air that comes from high areas. The situation of the grow room can be decisive in terms of temperature and humidity. Basements tend to have more humidity, but a more constant temperature. Attics are usually very hot in summer and cold in winter, although they do not have humidity problems.
We hope this information is useful to you. Shortly we will explain a little more about the importance of CO2 for growing marijuana.