Fresh Air (& CO2) for Cannabis

The air quality of your cannabis growroom is an important part of your grow. Cannabis plants use gasses in the air as part of their growing process, if these gasses become depleted then it can have a detrimental effect on your plant. It is extremely important as a cannabis cultivator to make sure that the supply of air is kept fresh to stop any potentially bad side effects.

The major gas used by your cannabis plants is CO2, or carbon dioxide. The plants use this in conjunction with water and light to preform photosynthesis, the means by which plants make food. If any of these requirements are lacking then your plants cannot perform at maximum efficiency and you will end up with a harvest below the strain's potential.

Normal, fresh air generally contains between 300-500 parts per million of carbon dioxide. In an outdoor setting this is constantly refreshed through natural means, allowing your plants to never run out of their supply. In an indoor setting this natural refreshment does not take place, to boot, the optimal level of carbon dioxide content is 1,000-1,400 parts per million for cannabis plants. This optimal level is the absolute peak of potential production though, you can still achieve great results without it, it is only a target for growers who not only want to keep air content fresh, but also push it to the absolute extremes with additional methods.

The easiest way to ensure that your plants have enough carbon dioxide is to make sure you have a well thought out, effective ventilation system. Usually you will an inlet fan low to the ground bringing in fresh air and an outlet fan above your lights to draw out the hotter, older air. This creates displacement, as the higher air is removed from the room it creates a vacuum and draws more air in from below. This should go some way to ensure that your plants have at least the healthy amount fresh air that they require.

So how does carbon dioxide affect your plants throughout the stages of their lives? Well, for the grower, the most important times are the vegetative stage and the flowering stage.

During the vegetative stage, an optimum level of carbon dioxide ensures that your plants have the building blocks to make as much food as they can. This will allow for the fastest, strongest possible growth your strain can achieve. It should be noted, in order to achieve optimal growth, your plants are also going to need the perfect amount of water and light as well.

During the flowering phase, an optimal level of carbon dioxide can improve the amount of initial bud growth. Most experienced cultivators have come to the consensus that adding in additional carbon dioxide for the first 2-3 weeks of flowering will get you a more bountiful yield. It is thought to lose its effectiveness after these 3 weeks, but some cultivators are of the opinion it does not and will give it additional carbon dioxide throughout the phase.

It must sound pretty appealing, adding extra carbon dioxide to your room to get a better yield? But there are a lot of things you must consider first. Whilst it is easy for a cultivator to maintain a healthy amount of carbon dioxide in their growroom, it is a real art to have your plants in a condition where enrichment to optimal levels will benefit them.

The first massive obstacle for most greener cultivators is that you must also maintain the optimal levels of lumens (light), water and nutrients for your plants to gain a benefit from the additional carbon dioxide. If your plants are suffering in any way, such as lack of a certain nutrient, or not having enough light to photosynthesize the extra carbon dioxide, then your cannabis plants are not going to be able to harness the extra power you are giving them. A nutrient deficiency is going to harm you yield a lot more than the extra amount carbon dioxide can potentially give you.

Next, if you plan to use extra carbon dioxide then you must make sure your room is sealed to stop any of it seeping out and becoming wastage. This would obviously mean shutting off your ventilation to make sure it is not accidentally removed from the room, but you will also need to consider and gaps in the walls, doors etc. As you release additional carbon dioxide into the room it will push out other air, if your room is not airtight then you may find that it is the extra carbon dioxide being displaced and pushed out of the room.

If you decide to enrich your growroom with carbon dioxide then you will find that the temperatures you normally keep your plants at do not apply. In order for your plants to fully utilize the extra carbon dioxide the temperature of your growroom will need to be 85-95 degrees Fahrenheit, ( 30-35 degrees Celsius). If temperatures are below this then you will not see much in the way of results. However, if your room is sealed and your ventilation is off then it is quite easy to maintain the correct temperatures, your room is going to heat up naturally. In fact you may find you struggle to keep them down.

You will also have to consider your growroom setup. Pure carbon dioxide is heavier than its mixed air counterpart. For this reason you will want to make sure the carbon dioxide enrichment method is above your plants, so that the carbon dioxide can fall onto them, as it will sink to the floor.

Maintaining the correct level of carbon dioxide can sometimes be quite tricky. Whilst cannabis plants require quite high levels in order to produce extra yields, giving them too much can be detrimental to their health. Anything above 2,000 parts per million is likely to kill your plant.

Finally, the optimal levels of carbon dioxide for a cannabis plant are too much for a human. It requires 5,000 parts per million to be extremely toxic to a human, but the levels required for enrichment are still not going to do you any favors. As a result you will want to avoid being in your growroom as much as possible whilst enrichment is taking place. This can make monitoring the conditions quite hard.

As an extra note, it is useful to know that plants only use carbon dioxide as part of the “daytime” process of photosynthesis. They do not use it at night. This means you should only enrich the plants during the time your lights are on. Using extra carbon dioxide during the night phase of your photoperiods is a waste.

As you can see, there are many factors and extra hoops to jump through if you want to enrich your plants. A constant supply of fresh air with a well thought out in/out ventilation system will be enough to make cannabis plants grow healthy enough to satisfy most cultivators. Enrichment is really only for the most serious, diehard and skilled of growers.