Climate control

Climate control

To achieve the best results from your plants, you will have to control the climate in your growroom. The three most important aspects are: temperature, humidity and ventilation.


TemperatureAlthough there are differences between different varieties of strains, cannabis will develop best between 20 and 30 ºC. To minimize the temperature differences, it can be a good choice to put the lights on during the night and off during the day.

To keep the temperature in your growing space at an ideal value, you will need a fan-controller with thermostat. This way you can choose at what temperature the fans have to run at maximum power.


When you are growing marijuana indoors, you need to keep in mind a cannabis plant cultivates best with a high humidity grade during the growing cycle. It’s recommended to keep this level around 70 - 80%. By doing this, you will get a faster cultivation of the plant.  During the flowering cycle it’s recommended to make use of a lower humidity level. Attempt to keep the humidity level at 65% during the first few weeks of the flowering cycle and lower this to reach 55% at the fourth week. Slowly attempt to lower the humidity level every week during the flowering cycle because when the buds are starting to develop, a too high humidity level can lead to bud rot. During the last weeks of the flowering period we attempt to keep the humidity level around 40-45%.Exhaust fan

It isn’t easy to maintain a perfect humidity level in your growing room. During the growing period you can easily create a nice humidity level with a humidifier . This will only succeed when your exhaust fan is turned off during the growing period. When the flowering period starts you can turn your exhaust fan back on to make sure fresh co2 rich air will flow into your growing space.

Humidity level has a huge influence on cannabis plants. Cannabis plants that have had a high humidity level during the growing cycle are better resistant against bud rot during the last weeks of the flowering period. While cannabis plants that had a too low humidity level during the start will get problems with bud rot faster in the last weeks when the humidity level is too high.


VentilationMaintaining a good airflow in your growing space is very important. You need intake holes at the bottom through which fresh air can enter your space and exhaust holes at the top to drain air to outside. It’s important that the intake and exhaust holes are not too close to one another. Cannabis plants need CO2 to grow and flower. If you don’t exhaust the air well enough, no fresh air will enter and also no new CO2.

The biggest problem while making intake and exhaust holes is that you have to make sure that the growing space also stays lightproof. There are many options that will do the trick as long as there is no possibility for light to come in your growing space.