For indoor cannabis grow rooms, many factors must be considered to optimize the quality and yield of your cannabis plants. One of the most important factors is relative humidity, which must be understood and controlled by the cannabis grower to ensure the health and quality of their crop are up to par.
While many other important factors come into play in your indoor cannabis grow room, relative humidity (RH) is perhaps the most commonly overlooked. Being able to properly manage the RH in your grow room is, however, key to optimizing your yield and hence maximizing your profit.
What is Relative Humidity?
In the simplest terms, relative humidity is a way of expressing the amount of water vapor present in the air. More specifically, it is a ratio of the amount of water vapor present in the air to the amount of water vapor the air could potentially contain at a given temperature. In other words, RH changes with the temperature changes as cold air cannot hold as much water vapor as warm air can.
Relative humidity is hence different from absolute humidity in one key way. While humidity is a measure of the amount of water vapor in the air, relative humidity is a measure of the percentage of moisture in the air relative to the highest possible amount of moisture the air can contain for a given temperature.
When growing cannabis in an indoor grow room, the RH is an important factor in creating the optimal growth environment. Temperature affects the humidity in the air, and the relative humidity in the room varies with the temperature. Therefore, controlling the relative humidity of your grow room means keeping both water vapor levels and temperature in check.
Cannabis plants require different amounts of relative humidity at different stages of growth. This is why it is so important to understand and control RH in your grow room. As cannabis develops through the seedling, vegetative, and flowering stages, the required RH will gradually decrease from 65 – 70% during the seedling stage to 30 – 40 % during the late-flowering stage.
The Impact of Relative Humidity on Cannabis
As mentioned, controlling the relative humidity of an indoor grow room is necessary for cannabis growers. Cannabis is a very sensitive plant. It needs to grow at a stable temperature and humidity to achieve an optimal and healthy harvest.
If the RH of your grow room is too high, this can negatively affect your cannabis plants in various ways. First, high humidity creates optimal conditions for mold to grow on your cannabis plants, which affects your yield. Further, when the relative humidity is too high, the cannabis plant struggles to absorb the necessary nutrients, which affects its health and growth.
If the relative humidity in your grow room is too low, it can cause cannabis to dehydrate and develop slowly.Oftentimes, low relative humidity can lead your cannabis plants to dry out and die, which will reduce your yield.
Understanding Relative Humidity for Cannabis Grow Room
To understand what constitutes low or high relative humidity, you must first familiarize yourself with the needs of cannabis plants. This will depend on the stage of growth they are in. During the seedling stage, your cannabis plants require a RH of 65 – 70% because of the underdeveloped root system. The high RH allows the plants to absorb water through the leaves.
During the vegetative stage of cannabis growth, the RH should be reduced by 5% per week. By this time the roots are developed and absorb most of the water while the lower humidity levels allow water to be evaporated from the leaves, in turn cooling the plant.
During the flowering stage, the RH of the grow room should be lowered to 40-50%. This helps the plants absorb enough nutrients through the roots.
How to Know the Relative Humidity of Your Grow Room
To control the relative humidity of your grow room, you will first need to measure and analyze it accordingly.
Measuring Relative Humidity
The best way to measure the relative humidity of a grow room is to install a monitor. Such a detector is available in many places and it is very practical and convenient.
A humidity chart can also be helpful when measuring the humidity of your room. Because it can help you to analyze how much to lower or raise the RH.
Analyzing Relative Humidity
While measuring relative humidity in your grow room is important, it is not enough. You will also need to analyze the RH in your grow room by trying to understand what factors are affecting the humidity and where the moisture is coming from.
Many factors can influence the amount of moisture in your cannabis grow room. If, for example, the grow room is overcrowded and the leaves of some plants are in contact with other plants, the humidity level of the grow room could remain high due to unnecessary retention of water.
Moreover, factors such as temperature changes, air circulation, transpiration, and watering amount also influence humidity. If, for example, the location where you reside experiences high fluctuations in average day and night temperatures, your grow room will also experiences fluctuations in RH. Further, poor air circulation and ventilation in your grow room can lead to water retention which will increase the RH.
Water tends to evaporate from the leaves of plants in a process known as transpiration. The level of lighting in your grow room will influence the rate of transpiration which has a large effect on the relative humidity levels. Finally, the RH levels of your grow room could be affected by watering your plants too much or too little. In summary, many factors can affect the relative humidity in your room. You need to be thoughtful when it comes to controlling relative humidity.
How to Control the Relative Humidity of a Cannabis Grow Room
There are two circumstances in which you will need to control the RH of your cannabis grow room: either when the relative humidity is too low, or when it is too high.
When it is too low
Use a Humidifier
By making use of a humidifier in your grow room you can increase the RH to an appropriate amount.
Increase Amount of Watering
You can increase the relative humidity of the grow room by watering more water. However, make sure that you are not overwatering your cannabis as doing so will lead to malnutrition.
When it is too hight
Use a Dehumidifier
By making use of a dehumidifier in your grow room, you can decrease the relative humidity to an appropriate amount.
Your grow room may be experiencing high RH due to poor air circulation. If this is the case, you can increase ventilation in the room so that the water vapor can escape and be replenished with fresh air.
Eliminate leaf Contact
In an overcrowded grow room where leaves of separate cannabis plants are in contact with one another, humidity levels could increase due to unnecessary retention of water. This can be controlled by spacing out your plants and picking up fallen leaves.
You can reduce the RH of your grow room by decreasing the amount of water you feed your cannabis plants. Just be sure that you do not end up providing them with less water than they require.
Altaqua Grow Room HVAC System for Ideal Humidity
Altaqua grow room HVAC system offers the perfect humidity and temperature control during the whole year round, no matter if it is summer or winter. This HVAC system can provide the dehumidification with both air conditioning and air heating after you set the target relative humidity and target temperature. Using this HVAC system the cannabis grower can create the best climate for cannabis development at every stage of growth.
Relative humidity is very important to understand, measure, analyze, and control in your indoor cannabis grow room. For this reason, the Altaqua grow room HVAC system is here to help you take care of your crop’s humidity needs.