How To Lower Humidity In Grow Tent?

If you’re an indoor grower, you can find issues related to humidity, which is risky and can cause problems. Whether you are experienced, you must know how important it is to have an optimal humidity level in your grow tent to grow indoor plants successfully. 

Whether you have faced the humidity too high in your grow tent, you should know how to decrease humidity in the tent. High humidity levels can’t cause slow growth, bud rot, fungal growth, mildew, and mold, and these factors may threaten the survival of plants. 

Ensure that humidity must not exceed 70% in your tent. Therefore, if it surpasses the level, you need to determine the source from where the moisture comes and what you need to do to stop it from harming your plants.

In this case, it is essential to maintain an adequate humidity level in your grow tent. This article contains a few points that let you know how to decrease the humidity in grow room. 

Understanding Relative Humidity

Humidity means the water vapor you can find in the air. In this case, relative humidity indicates the ratio of the current absolute humidity to the highest possible humidity. 

In short words, this term indicates the air wholly saturated with water vapor and the point at which it is unable to hold it any longer. You must remember that air always contains water vapor, and it can hold more water vapor when the temperature is higher. The heat can cause the water to move quicker through the air, which causes higher humidity.

Why High Humidity Is Bad And Causes Problems

High humidity is lucrative to make sure the strong growth and health of the plants. Plants indeed want high humidity. But it isn’t ideal to have excessive-high humidity levels in your grow tent, and otherwise, it will cause more harm than good. 

You must not want your tent to be an ideal place for bacteria and moulds. Therefore, you must prevent flowering plants from suffering bud rot or botrytis. 

Besides, try not to increase the threat from pests & diseases and don’t allow you to transpire or exchange air for your plants. You should also never encourage non-essential microbiological growth;

Try to decrease the carbon dioxide intake required for efficient photosynthesis. You can turn the roots dormant by diminishing them to take up water.

You need to reduce the plants’ nutrient uptake and decrease your plant yield. Thus, it is possible to realize how to balance the low humidity levels in a grow tent.

Importance Of Low Humidity In A Grow Tent

Usually, the humidity levels rely on the growing stage of the plant. However, you should know that low humidity can work wonders. If you find high humidity and moisture levels building up in a tent, it can cause the buds or flowers to rot.

There are other problems with high humidity, including:

White mould: It can pester the leaves, obstructing them from taking in water, air, and light.

Rust fungus: It can cause rust spots on the leaves. 

Root rot: The roots can begin rooting when the soil has too much moisture for too long. 

Grow Tent Size

It is the size of grow tent you need to consider. You must make sure that the relatively low humidity has covered all areas. 

For example, you can take the help of a 4×4 Grow tent that requires 40%, whereas a 5×5 grow tent will need at least 65%. 

If necessary, you can take the help of a residential dehumidifier in your 4×4 grow tent. Using a compact dehumidifier can offer better performance for a 2×2 grow tent by absorbing 8 to 10 ounces of moisture. 

What’s the best grow room temperature?

Temperature varies, but it’s needed to give you an idea of how to control humidity. Make sure you have a thermometer and hygrometer.

Clones or seedlings prefer 74-78 degrees Fahrenheit, whereas vegging plants can thrive at 70 degrees Fahrenheit.

Flowering plants require 88-75 degrees Fahrenheit temperatures than those ready to be harvested, which are good at 65-74 degrees Fahrenheit.

What’s The Best humidity level?

Plants generally require different humidity levels during all the life stages. If you have Seedlings or clones, these will require 70% to 75% humidity. It is because these need time to allow the root systems to develop, and thus, it makes them dependable on the leaves to absorb water.

While you feed the baby plants, it indicates that you will have a lot of moisture in the air. It is one of the reasons why indoor growers prefer to use propagation trays or humidity domes to generate moisture.

Vegging plants require 50% to 70% humidity as these consume water from the roots and leaves. When it comes to Flowering plants, the requirement of humidity becomes 40% to 50%, and it helps to achieve a comfortable environment to breathe.

If you harvest in a tent, it will require 45% to 50% humidity to ensure that the environment is not so humid. For indoor gardening, humidity becomes vital. 

If you are a gardener, you must know how to control the humidity levels completely, especially how it is possible to reduce them in grow tents. As a grower, you must know which humidity levels are perfect for different stages of plant growth and plant varieties. 

Besides, you must have the capability to combine different ways of reducing the humidity in a grow tent to balance relative humidity at advised levels. Humidity, temperature, and light are lucrative to raise healthy and robust plants.

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Here is How To Lower Humidity In Grow Tent

We have told before that it is essential to have high humidity. But it can harm if the levels become extraordinarily high. These are a few ways to decrease humidity in a grow tent.

1. Avoid Overwatering Your Plants

Suppose you are looking for an easy way to reduce humidity levels. Try to protect your plants from overwatering. Putting more water in your plants will boost the humidity in your grow tent beyond the correct levels.

Besides, soggy soil can leave extra water in propagation trays if you have soggy soil. As a result, it can raise humidity levels.

2. Use A Dehumidifier Inside Your Grow Tent:

If your tent is too humid, you need to use a dehumidifier. It can help you to remove excess moisture in the air to lower humidity levels. You may spend money on this as a grow tent requires a commercial dehumidifier. You have to invest in resources to assure plant growth and yields.

Whether you find the place humid already, using a quality dehumidifier connected to a drain is recommended. If your living place contains less moisture in an area, we recommend you to shut off the device and drain it whenever it becomes full.

The dehumidifier can help you to remove at least the same amount of water absorbed by plants regularly. In addition, you can purchase a dehumidifier with at least a one-gallon water tank capacity. It helps you to save time from filling it up often. 

You can locate your dehumidifier in the middle of your grow tent if you want. A few dehumidifiers come with an automatic shut-off feature when complete. It is possible to set a timer and monitor the amount of water your dehumidifier collects. Placing the inlet and outlet of a humidifier inside your grow tent can heat the space. 

3. Check Your Plant Density 

Plants usually release carbon dioxide helping to release the temperature in your grow tent. Therefore, the moisture can build up, causing humidity to increase.

Increasing the plant number helps to displace the air in your grow tent, and it does not allow other areas to get fresh air and carbon dioxide. 

Plants transpire water vapour. But it can be trapped when your tent does not have any correct dehumidification or ventilation. Whether you don’t want to remove plants in your grow tent, you need to move the plants only with huge leaves.

4. Remove Stagnant Water 

There is no necessity to invest a lot of money to reduce humidity levels in a grow tent. If you’re looking for an affordable option, removing stagnant water is excellent. 

Like indoor growers, you have to ensure that your grow tents can offer proper drainage, and it helps stagnant water not pool on the ground and includes excessive humidity.

The issue you can face with stagnant water is that it may cause molecular oxygen to decrease to such a level where bacteria form and thrive. Ensure that you must not leave water reservoirs exposed or allow stagnant water to form puddles on the floor.

Otherwise, it can release moisture into the air. You obviously don’t like to have a tent which is a breeding ground for pests and bacteria.

4. Improve Ventilation By Adding More Fans

It is advised to put more exhaust fans or increase the fan rotation to improve ventilation. When you increase ventilation, it can elevate the amount of airflow more practically in the grow tent. 

If you can, take the help of an atmospheric controller with a humidity setting. It helps you to set the fan speed automatically to attain the level of humidity you desire. Venting a duct fan or opening a window to push moisture out of the grow tent is very easy. 

It can work only to reduce humidity while the intake air comes with a lower RH than the air in the grow tent. Following this procedure, it is possible to drop humidity levels. In this case, the positive pressure inside helps to make sufficient air movement to offer a gentle breeze all over your grow tent. 

Ensure that you should have an outflow fan that comes in a large size than your intake one. However, it is recommended not to depend on oscillating wall fans only as these may fail suddenly to secure air circulation. They can help you to decrease the temperature on the canopy.

Having good airflow must come from a grow tent’s wall, top surface, and bottom surface when you want to have good airflow. We recommend you buy floor fans to pull air through the canopy. Thus, it can assure you that you will get equal carbon dioxide distribution.

Try to have a guaranteed stable temperature and balanced humidity levels, resulting in a successful harvest. Depending on experience, you need to use a hygrometer controller, which is lucrative for powering fans. You will get more efficient than using a thermostat or timer.

5. Create Air Holes

When you create wide or narrow holes in the grow tent, it helps you to regulate the airflow. If you are willing to reduce humidity, it helps to make widened holes to ensure more air gets in than gets out. Ensure that you must not allow any unwanted light to enter.

6. Purchase An Air Conditioner

Air-conditioner helps to cool the air enabling you to reduce humidity levels. It takes the help of compression and gas to pull out the heat of the air, and it can generate condensation that can remove the moisture effectively from the air. 

The big AC units allow you to run on short cycles or brief periods, and it helps to generate an unreliable environment for your plants. Besides, small AC systems can help you to raise the temperature slowly. 

It is also one of the most frequent fluctuations causing your temperature to grow tent to soar. Try to use a good air-conditioner that can ensure that cold air replaces hot air. 

If you are willing, you can decrease water vapor by pairing up with a fan to maintain a cool environment in the tent. Ensure that you have to choose the correct sized air-conditioner for the grow tent, which pulls enough water from the air.

You must remember that you have to clean the filters, and it is because clogged ones can prevent a perfect airflow raising the humidity.

7. Insulate And Seal Your Grow Tent

You must ensure that you have insulated and sealed the tent accurately. It is one of the features which is essential to controlling humidity. 

You can take the help of foam insulation to create a thick barrier between the outside environment and a grow tent. There are multiple factors that can pose a threat to your plants.

8. Use Grow Equipment Wisely

Using grow equipment, including grow lights, helps you to elevate the temperature in your grow tent. You need to buy a grow light which doesn’t emit plenty of heat.

Whether your tent has a warm environment, you need to power off the lights to have a temperature drop. Keeping the lights switched off helps to save on electricity bills.

9. Make Use Of Absorbent Soil 

If you are an indoor grower, you must have heard that different soils are suitable for different plants. You can use soil to decrease humidity in a grow tent, and it can keep water underneath. 

It is recommended to use sandy soil to decrease evaporation rates and water used on the surface. If necessary, you can choose perlite. However, you can use sandy soil, which is available at a cheap rate and can enable you to change the soil frequently.

You will benefit from using lime or baking soda similarly while using sandy soil. In this case, it is necessary to avoid any material or soil that can generate dampness, and you must use the absorbent surfaces hence. 

10. Consider Defoliating Your Plants 

It is another convenient way you can use it. Leafy plants or plants with huge leaves can increase humidity levels in your grow tent. However, if you are willing, you can cut down some leaves to not cross the recommended humidity level.

Things to Do to Avoid Further Raise in Humidity

Insulate Grow Space from Outside Humidity:

You may find the humidity level increasing higher. Even you can not put it down by giving so much effort. 

The indoor garden might have a direct connection with a too-humid outside environment. Sometimes, your living place may contain higher humidity levels. For example, New Mexico or Colorado are some locations where humidity levels are high. 

In such cases, the commercial growers take the help of barriers like foam insulators to prevent the situation. You can insulate the grow area efficiently for a grow tent. 

Don’t rely on One-dimensional ventilation:

When correct ventilation occurs across the whole grow room, the air does not get saturated with water vapour. Ensure that you must not depend on merely the oscillating fans. It is because these can decrease the temperature of the plant canopy. 


1. What causes high humidity in grow tent?

If the temperature in the tent is higher, the air can hold more water vapor, and heat in the tent allows the water to move faster through the air causing higher humidity.

2. How do you regulate humidity in a grow tent?

If you are willing to regulate room humidity growth, do the following. 

  • Make sure that you have insulated and sealed it properly. 
  • Balance a specific temperature range. 
  • Boost the cool air supply.
  • Ensure that the stagnant water pools don’t form.
  • Take the help of an appropriately sized dehumidifier. 

3. How do you bring your humidity down?

If you want to decrease humidity levels indoors, follow these ways.

  • Improve the ventilation of your home.
  • Use desiccants
  • Power on the air conditioner.
  • Dry your clothes using a dryer or outdoors.
  • Use dry surfaces.

4. How do you remove humidity from a tent?

You can reduce humidity in these ways: 

  • Ventilation 
  • Stake the tent out completely
  • Don’t Cook Inside 
  • Wet Clothes and Gear can add moisture to the tent.

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