Cannabis likes breeze and fresh air. When growing marijuana indoors, we can equip her with a ventilation system to imitate the natural environment.
The importance of good air circulation for cannabis cultivation
Good air circulation will promote the growth of marijuana and reduce many common problems in the indoor cultivation process. The specific advantages are:
Stronger stems, greater yield. The blowing of the breeze can stimulate the stems, making the stems stronger and bearing more branches and flowers.
Maintain an optimal growth environment of 20-30 degrees Celsius and 40%-80%. Prevent excessive humidity and high temperature from damaging the growth lamp.

Prevent mold and pests. Spider mites and fungi like to grow in a warm, humid and windless environment. Good ventilation can effectively eliminate many parasites and molds.
Reduce the smell of cannabis itself. Equipped with a charcoal filter to absorb the smell of cannabis and pesticides, making your planting safer and more concealed.
Help high-efficiency discharge lamp heat dissipation and prevent fire.
How to equip ventilation facilities?
This is the ideal ventilation facility.

An intake fan is equipped at the bottom, and the power of sucking in fresh air from the outside does not need to be too large. Generally, a quarter of the power of the exhaust fan is enough. The stems of the plants are equipped with a small wall-mounted fan, imitating the breeze blowing Buddha, helping the plants keep dry and promoting the stems to become strong. Then at the top, according to the shape of the lighting facility, a charcoal filter and air outlet exhaust fan are equipped, and the middle is connected with a pipe.

Set the distance between the fans as far as possible to enhance the air flow. The power of the fan does not need to be too large, just like a gentle breeze in spring. If the planting space is large, the power can be appropriately increased. Excessive wind will damage the plant. The leaves of marijuana will bend downwards, and the left and right sides will be fastened downwards.
The specific selection can refer to the following figure, CFM is the flow unit, 1CFM is 28 liters per minute.
Expanded space size (feet) | Average light consumption | CFM of fan * |
2’x 4’x 5’ | 250Watts | 80-120 CFM |
3’x 3’x 6’ | 400 Watts | 108 – 162 CFM |
3.5’x 3.5’x 6.5’ | 600 Watts | 160 – 238 CFM |
4′×4′×7′ | 1,000 Watts | 224 – 336 CFM |
If high-intensity discharge lamps are used, the power of the fan can be appropriately increased. The best choice is to buy a ventilating fan and air intake fan with high power and adjustable gears. After selecting the fan, add a charcoal filter, and then configure the pipes according to each size.
In order to increase the photosynthesis of plants, we can also configure a carbon dioxide generator to increase the concentration of carbon dioxide in the air.
If the smell of marijuana is too great, we can also equip an ozone generator to remove the smell.
The correct installation steps should be

- Build a growing tent
- Install lighting equipment, adjust the lighting equipment to a suitable position and height according to the number of cannabis plants and the required light intensity.
- Install the fan and charcoal filter. It is recommended to install the charcoal filter in the first link of the air supply system to allow the charcoal filter to absorb the smell to the greatest extent, so as to prevent the lighting equipment and other links of the air supply system from being polluted. Try to install the ventilation fan and air intake fan in the tent to reduce noise. If the internal space is too small, it can also be installed outside.
- Install the gas outlet pipe on the wall or window so that the gas can be discharged outside. Some growers will set the outlet of the air supply pipe indoors, which will increase the humidity and temperature of the room, make the room hot and humid like a sauna, and seriously damage the house. Pay attention to camouflage if the vent is set outdoors, so that it looks like the vent of a water heater or range hood.
- After installation, test each fan one by one separately, and then test as a whole when you are sure that everything is ok.
After configuring the ventilation system, the construction of our indoor planting environment has been basically completed, to ensure that everything is safe, and then you can start your planting journey.