Where to Place Dehumidifier in Grow Room

Plants need proper humidity levels for their health and growth. Too much water will drown the roots, leading to rot and decay. Plus, too much moisture can impact the structure of your building. To keep moisture levels in the right range, one effective solution is to use a dehumidifier in your grow room. However, proper humidity control doesn’t stop at getting a dehumidifier, you also need to find the right placement for your unit.

For small grow rooms, a single dehumidifier should be enough for the area if you maximize the airflow. For rooms that are larger, you may need multiple units spaced evenly for maximum coverage. If you have limited floor space, overhead units can be installed above the grow lights for optimal efficacy. Finding the best placement can make all the difference to your dehumidifier’s effectiveness.

Where to Place Dehumidifier in Grow Room

Dehumidifiers come in many sizes with different features you may need. Choosing the best dehumidifier for your grow room and finding the best placement will depend on multiple factors.

Ideally, you want your dehumidifier in a position where it can cover the whole space and address your humidity problem right at the source. Place your dehumidifier close to the power supply but at a distance from your plants and other items if it’s on the ground. If you have a grow light, a suspended dehumidifier may be placed next to it. You want your dehumidifier where you can easily access it to make sure it’s working correctly and check the drainage to avoid any problems. If you have a floor drain or sink nearby, you can use the continuous draining option.

For more details, below are the main considerations you should make when placing your dehumidifier in a grow room.

Plants inside the room

Effective Range Of Your Dehumidifier

The best dehumidifier placement mainly depends on the size of your grow room and the capacity of your dehumidifier. For instance, a large grow room may need more than one unit so you need to balance the space between each unit to maximize coverage and efficiency. The dehumidifier capacity is the most important specification you must check before making a purchase. The manufacturer should indicate the recommended area of coverage for each model. Usually, a larger capacity can effectively cover larger spaces, but this varies per brand and unit.

If your grow room is small enough for a single dehumidifier, the center of the room may seem like the best location for your unit. However, this may not be optimal if your plants are on the walls of the room farthest from the dehumidifier. The best location would be close to wherever the humidity is highest.

Consider the number of plants in your grow room and the amount of water they need daily. In general, plants release the same amount of moisture that they absorb. For example, if you use 30 pints of water for your plants each day, then you’ll need a dehumidifier with a capacity of 30 to 50 pints.

Maximize Airflow for the Dehumidifier

The airflow, measured in cubic feet per minute (CFM), is the rate at which the dehumidifier processes the air. It is a common misconception that a higher airflow means a larger coverage area, but it can vary greatly between different brands and models. More airflow promotes even circulation throughout the room and helps the moisture evaporate faster.

To maximize circulation in the room, make sure there are no obstructions to the airflow that might cause uneven dehumidification where some parts of the room stay humid. Place the dehumidifier away from walls and other items inside the room or it could block the airflow. Do not point the air inlet and outlet directly at the plants.

Placement Options For A Dehumidifier in Grow Room

For commercial growers, the best spot for a dehumidifier is usually above or to the side of the grow lights in the room. But for home growers or if your room simply has low ceilings where you cannot hang your dehumidifier, then you can use a free-standing dehumidifier and place it on the ground and under the grow tables, where possible. 

In this case, you can use a high-capacity portable residential dehumidifier and run it like you would for any other room in your house. This also makes it easier for you to move the unit anywhere in the room to monitor the operation or perform maintenance. You should also think about the drainage area where you plan to dump the collected water. You can use the reservoir and empty it manually, or use continuous draining through a hose if you have a floor drain nearby. Again, remember not to place the unit too close to the walls or any other items to promote airflow.

For larger grow rooms where every floor space is more valuable, overhead dehumidifiers are ideal to save space. These units can be suspended from the ceiling for a fixed installation. They usually come with the necessary tools for setting up, but once installed on the ceiling, they can be difficult to move. Thus, if you get one of these units, it’s important to really think about the location before installing. One good location would be above your grow lights or where the highest growth density is. When locating these units, you should also consider where the drain will go.

Another option is to duct the dehumidifier outside from a separate room. This is best if you have limited space inside and already have existing ductwork for your HVAC system. The ducts run from the room to draw the moist air into the dehumidifier, then the dehumidifier collects moisture from the air and sends it back to the room. 

How Does Humidity Impact The Health of Your Plants?

Humidity plays a significant role in each stage of a plant’s growth. If moisture levels are too low, the plant roots cannot absorb the water they need. If moisture levels are too high, the plant drinks water through the leaves and the roots may drown, taking less of the oxygen and other nutrients it needs from the soil. 

Too much humidity promotes the development of other organisms such as mold and mildew, which can directly affect photosynthesis. It can prevent the absorption of water, light, and air through the leaves. Once a small part of your grow room is infested with mold, there is a high chance that it spreads to the rest of your plants. Pests in your plants also thrive in high humidity.

What Causes High Humidity in a Grow Tent

There will always be humidity when there is heat and water present. So when there’s too much water in your grow room, it results in high humidity. Plants give out moisture into the air as they transpire, and any open water systems such as hydroponics can also raise the humidity level in the room.

When you water your plants, they absorb the water and release the excess into the air. So, if you overwater your plants, they also produce extra moisture. Inadequate ventilation and lack of airflow also prevent the exchange of the stale air inside with the cool fresh air, adding to the humidity in your grow space.

Should You Put A Dehumidifier In A Grow Tent?

If you are growing in tents, you may place a dehumidifier inside or outside the tent. However, a dehumidifier sitting outside of the tent will have limited access to the moist air inside, reducing its effectiveness. You can also connect a duct into your grow tent so you can dehumidify it from the outside through the vents. Alternatively, for smaller tents, you can use a mini dehumidifier inside to help keep moisture levels down.

When running a dehumidifier, make sure that the tent is tightly sealed for maximum efficiency. Before you buy a dehumidifier for your grow tent, you also need to calculate the dimensions of the grow tent’s available space to choose the right size dehumidifier. Each unit should be marked to indicate the recommended coverage area.

How to Know if You Need A Dehumidifier In Your Grow Room

Since grow rooms have limited natural airflow, you will have to interfere and create the perfect conditions for your plants. The climate in your area will affect the temperature and relative humidity inside your grow room, and thus affecting the health and growth of your plants. In excess, moisture can also become harmful to your health.

The optimal range of relative humidity for you and your plants is between 35 and 55 percent. Anything below or above this range can be dangerous to both people and plants. If you feel the air is too heavy or sticky on the skin, this is a sign of high humidity.

Condensation on windows or any colder surface of your grow room, and musty odors you can’t place are some of the first signs of humidity.

White, fuzzy mold or powdery mildew on the leaves or stem indicates high humidity. Mold can be dangerous to plants. In particular, bud rot is a type of mold that develops inside cannabis buds and it can be hard to spot and eliminate. Once an area of the room is infected, there are high chances that it spreads to the rest of your plants. 

When you see pests such as aphids, ants, caterpillars, or spider mites, that may also mean you have high humidity. Another sure sign you have a humidity problem is when you find puddles of water. Too much water can damage your plants and make your soil more hospitable to unwanted organisms. 

If you notice any of these signs in your grow room or tent, you should probably invest in a dehumidifier for indoor growing.

How to Lower the Humidity in Your Grow Room 

Before using a dehumidifier, there are a few other ways you can prevent control moisture and prevent high humidity in your grow room. First, ensure that it is properly insulated to maximize the efficiency of your electrical units like an air conditioner, or fans and lights. It also helps maintain the temperatures inside during extreme weather conditions or sudden temperature changes outside.

Plants naturally produce moisture as a part of photosynthesis. The amount of water you feed them is the same amount that evaporates into the air as moisture. So to prevent excess water vapor, avoid overwatering and always drain any stagnant water in the area. 

It’s also best to increase ventilation inside your room or tent. If possible, install fans to help your dehumidifier circulate the air. If there is a grow light, ensure that the heat is just right, or use it only during the coolest time of day. Remember to also put enough space between your plants to let the air circulate better.

High humidity can bring a variety of problems to your grow room. Depending on the size of your grow area, its current conditions, and the requirements of your plants, a correctly sized dehumidifier is the most effective solution for humidity control.


Indoor growing allows you to cultivate plants out of season due to the controlled environment. This includes maintaining the right temperature and humidity levels throughout the plant’s growth. Different plants thrive in different environments. Low humidity can cause excessive dryness in the air that can negatively affect the plants. On the other hand, high humidity promotes mold growth which can be harmful to plants and to your health. To solve moisture problems in your grow room, a dehumidifier is a good investment. Getting the right dehumidifier size is as important as finding the best placement for it. This maximizes the unit’s effectiveness and efficiency, ensuring even distribution of healthy air throughout the room.

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