How To Lower Humidity In Grow Room

Humidity is one of the factors that are frequently overlooked in the whole processes of managing plants in a grow room. The plants require different humidity at different stages of development. At flowering, for example, you need to be fully aware on how to lower humidity in grow room.

The role of humidity cannot be overlooked or underrated. Lower humidity than needed prevents photosynthesis and similarly, is high humidity. Without or with struggling photosynthesis, your plants will be at risk. Controlled humidity comes with several advantages.

Why High Humidity Is Not Recommended In A Grow Room

A high level of humidity is not recommended in grow room for various reason. The main reasons are:

  • It prevents the plants from transpiring effectively.
  • Reduces the plant’s water intake ability.
  • Harbors a good site for bacteria to thrive.
  • High humidity encourages unwanted growths.
  • Encourages the growth of molds.
  • Reduces the intake of carbon dioxide necessary for photosynthesis

There are two main things that should be checked to achieve the desired level of humidity in a grow room.

  • The temperature in the grow room.
  • Air flow in the grow room

It should be noted with a lot of keenness the great role of humidity in plants development. To reduce humidity in your grow room, read the steps as mentioned below.

Steps To Lower Humidity On Grow Room

Step 1- Ensure proper ventilation

Air flow in the grow room is one of the main determinants of humidity inside it. An increase in the air flow lowers humidity while a decrease raises the humidity. Set mechanism to regulate the airflow in the grow room.

Make air hole

One of the ways of regulating the flow of air in the grow room is by creating, widening or narrowing the air holes. In the case of high humidity, make sure that the air hole in the grow room is created or widened to have more air in and out. In the process of creating the air hole, make sure that your hole does not allow unwanted light in.

Use fans

Another effective way is by having inflow and outflow fan. Always ensure that the outflow fan bigger or more effective than in the inflow in case you need to reduce humidity.

Air conditioners

Air conditioners that help you manage hot air out through the top and let in cold air through the bottom are also advised. To achieve the best, this cost can be incurred.

Step 2- Limit Grow Room Heat

If you have the ventilation set right, check for the heat in the grow room. With the rise in temperature, air tends to hold more moisture. When there are very high levels of moisture in the grow room, transpiration tends to be affected.

Keep the plant's environment cool

Having air conditioning facilities in the grow room is one of the ways that ensure that your grow room temperatures are regulated and kept in check. This ensures that hot air is frequently replaced with cold air. Keeping a fan also helps keep the plant's environment cool and the vapor reduced.

Shop grow light wisely

Heat is limited in a grow room by checking your grow light to monitor heat emissions. Different grow lights emit heat into the grow room and therefore there is a great need to choose the grow light wisely. To ensure that the humidity is kept low, go for the grow light that does not emit a lot of heat.

Step 3 - Avoid too much water

So far, you have dealt with heat and air. If now you have the air flow and the amount of heat present regulated, the next big thing is to control evaporation water.

What you should always remember the following when dealing with grow room water:

  • Your plants can’t do without water. The plants need enough water for photosynthesis and other plant water uses.
  • This water meant for plants is the same that dampness the moisture in the air.
  • The ground should not be watered until soggy. Limit water level on the surface.
  • Too much water on the surface leaves the air having too much moisture.
  • The air circulation in and out as well as the regulated heat cannot clear all the moisture.

The need to keep the water limited to only what the plants need at different times cannot be overemphasized. The ground should also not go dry as this will lower humidity below recommended levels.

Step 4 – Absorbent Surface

One other major thing to do when monitoring humidity is checking on the ability of the ground to keep water underneath. The type of soil you use in your grow room matters here. Any soil or material that creates dampness should either be avoided or covered.

There are two major changes you should introduce to the ground.

Use sand on your surface

The sand should be replaced frequently. Sandy soil is highly porous and thus allows the water to drain down while preventing evaporation. Sandy surface is advantageous in two ways:

  • It minimizes the amount of water on the surface.
  • Minimizes the rates of evaporation. This is because water is not directly exposed.

Use lime or cat litter

The second way of dealing with the ground is using baking soda or lime. Lime and sand enjoy similar advantages.

All these should be replaceable and are put there with a view to ensuring that the rates of evaporation are reduced. With reduced evaporation, the amount of moisture in the air is greatly reduced thereby giving the plants the best environment to transpire, grow, access nutrients and yield. Dampness is the enemy here.

Step 5 – Use Dehumidifier

When all the ground is set and ready, you are comfortably supposed to monitor the humidity through the necessary machines. Instead of just monitoring and checking on nature’s provisions like air, heat, and water have a dehumidifier.

Enjoy the advantages of a dehumidifier:

  • A dehumidifier absorbs that humidity that exceeds a set limit.
  • It switches itself off when the humidity is normal.

Putting all other things and factors in the right order and leaving the changes unmonitored is still risky to the desired yield. Leave nothing to chance by putting a good quality dehumidifier in the grow room. To avoid overworking the machine, have the above four steps should be closely and keenly set.


Humidity is a basic factor to monitor in growing plants. In grow rooms; you must take full control of the humidity in it and know how to lower humidity in grow room. All you need is check out for two main things. Firstly, it is to know what humidity levels are needed for each stage of your plants. Secondly, you should know how to lower humidity in your grow room to keep it in check.

There are natural and cheap ways of reducing humidity in a grow room. These have been discussed as including control of air flow through ventilation and air conditioning, regulation of heat in the room and limiting the amount of water on the surface.

These three are very effective. You can, however, incur minimal costs and have a dehumidifier. The machine is the sure way that you’re getting nothing short of the best - the prescribed humidity itself. Go for it.