High humidity in veg

Humidity is measured as RH which stands for Relative Humidity. It is a measurement that detects how much moisture is in the air. It is important when growing cannabis to keep RH levels within the correct range according to the plant’s current stage.

During veg it is preferable, but not crucial, to have high humidity inside the grow room. Between 60% to 80% RH is a great range for young cannabis plants in vegetation.

The easiest way to increase humidity is to use a humidifier that continuously sprays water into the air to keep RH levels higher. Other methods are placing a glass of water on a radiator, but this will not work as well as a humidifier.

It is important to note that humidity and temperature are closely linked. If the grow room temperatures are higher at around 30 Celcius, then it is very important that the humidity is high at around 80%. Once the temperatures are around 30 celcius the plants’ need for water will go up drastically as the hot and dry air sucks water from the plants which causes the raised edges around the leaf along with heat stress.

Here is a very helpful graph that shows the ideal humidity range for cannabis vegetation compared to grow room temperatures. During flower, humidity is kept much lower to avoid issues such as bud rot.