Condensation in Grow Room

How to Stop Condensation in Grow Room?

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Condensation shouldn’t be allowed in your Grow room at all cost. It will cause a huge damage to your plants – you won’t get great yields.

And no one wants that.

In this article, we will discuss simple ways to stop condensation in a Grow room. We will also discuss other critical things you need to know about condensation.

Let’s get started.

What Exactly is Condensation?

Condensation is the physical process whereby water vapor changes to water droplets and settles on the cooler parts of your grow room.

If you can see water droplets on leaves, stems, and other objects, this is a sign that there is condensation happening in your Grow area.

As an owner of a Grow room, to stop condensation from happening, you need to know how it occurs in the first place.

Naturally, condensation is caused by two processes:

  • Changes in temperatures in the grow room.
  • Changes in humidity levels.

For condensation to occur, humidity and temperature have to be conducive. When humidity is high, and the temperature is low, condensation will take place.

To prevent condensation from happening in your grow room, you need to set the optimal level for temperature and humidity. Your grow room needs to be designed in a manner that temperature and humidity are kept within the required range.

Optimum Temperature and Humidity for Your Indoor Grow Room 

Technically, the ideal optimal levels of temperature and humidity will depend on the growth stage of the plants.

In this section, we will look into the optimal levels of temperature and humidity; we will look at it from the different plant growth stages.

  1. Temperature

Seedling Stage – 740 F-750 F

This is the initial stage of growth. The seedlings are not developed well enough. To ensure seedlings thrive well, temperatures need to be 740 F-750 F.

Vegetation Stage – 700 F- 780 F

In the vegetative stage, your plants have developed the much-needed roots. The growth rate at this stage is very high.  Optimal temperature ranges between 700 F- 780 F.

Flowering Stage – 680 F-750

At the flowering stage if you are regulating the temperature with by supplementing CO2, then the temperatures could be raised to 750-820 F., but regularly, the temperature is maintained at 680 F-750

Harvesting Stage – 650 F-740 F

In the final stage, temperatures in the grow room should be kept at 650 F-740 F during the day. Temperatures during the night should be cooler than during the day.

  1. Humidity

Seedling Stage – 75%-85%

At this stage, the seedlings do not have developed roots to absorb water. Thus, to ensure they survive to the next step, the optimal humidity level should range between 75%-85%.

Vegetative Stage – 45%-55%

Plants have already developed roots at this stage. Development growth is high, and humidity needs to range between Humidity 45%-55%.

Flowering Stage – 35% – 45%.

At this stage, humidity should be maintained at minimal. Optimal levels for humidity should range between 35% – 45%.

Harvesting Stage – 30%-40%

In the final stage, humidity should be decreased significantly to prepare for harvesting. Humidity at this stage should be maintained between 30%-40%.

So if condensation still happens, how would you go about it?

How to Stop Condensation in Grow Room

5 Methods to Stop Condensation in Your Grow Room

  1. Seal your Grow Room

Sometimes your grow room is not well sealed off, air from outside the grow room could gain entry. The outside air will have a significant on the environmental conditions in the grow room. the outside air has two effects:

  • The indoor temperature will unstable
  • The indoor relative humidity will fluctuate.

The combination of the two factors results in condensation. Use foam insulators to seal the places from the outside environment to ensure proper sealing off of the grow room.

Spray foam insulators along the walls to create a thick layer to achieve a tightly sealed room,  . This is a barrier between the grow room and the external environment.

Therefore, proper sealing of the grow room can help with your condensation problem.

  1. Adjust your AC

We already mentioned that temperatures play a vital role in the condensation process. Naturally, temperature determines the amount of relative humidity in your grow room.

Therefore, if your AC malfunctions or stops working, condensation could be the result. A malfunctioning AC will cause a fluctuation in temperature in the to grow room.

The two causes that might cause the AC to malfunction are:

  • The thermostat range.
  • The short cycling.

Thermostat Range

If the set range of the thermostat is small, and the AC is oversized. The AC system will exhibit brief periods of short cycles.

When the AC kicks in to stabilize the temperature, it will consume lots of energy. In the end, the temperature and humidity will regularly be fluctuating.

Short Cycling

We have already seen that short cycles will occur for oversized and undersized AC. Such AC will not be able to regulate the ecological conditions inside the grow room.

It is advisable that before purchasing an AC system, you should consult whether your grow room size is compatible with your AC system. Some AC is known to raise the humidity levels in the grow room. If that is the case, then changing it would be a priority.

The following are high-performance ACs that you need to consider and purchase for your grow room.

Consider an AC that matches the size of your grow room.


the AC has an airflow of 205 CFM, and it’s designed for ventilation of hydroponic grow rooms.

Key Features

  • Quite 4” inline Duct fan with controllers for temperature and humidity.
  • Ventilation exhaust fan for heating and cooling booster.
  • Efficient in power consumption
  • Extremely less noisy


The AC has an airflow of 740 CFM, and it features an 8-speed manual controller that is utilizing PWM.

Key Features

  • Has a quite 8” inline Duct Fan that has a speed controller.
  • A relatively high airflow capability, 740 CFM.
  • Had a corded AC power plug,
  • Designed for large-sized grow rooms.


The AC has an airflow capacity of 120 CFM, and it is 6″ in size.

Key Features

  • The AC is designed for small grow rooms
  • It is power efficient
  • Extremely less noise
  1. Allow Air Circulation

Even after installing the right AC and sealing off the room, there is still condensation. Then, you might consider checking the ventilation system for any anomalies.

The addition of ventilation valves increases the amount of humid air removed from the area. To increase the humidity in the room, consider reducing the number of ventilation shafts.

If you do not have a ventilation system in place, then consider having one installed. Most people install a style shaft to work as a ventilation system.

Having an efficient schedule for a fan runtime will do the trick.

To boost air circulation, buy Grow tent fans. The following are the best fans you can buy from Amazon and install them over your Grow tent.

TJERNLUND M-67 Inline Duct Booster Fan

The fan attains a power output of 460 CFM. This means it can run for a long time without changing its performance.

Key Features

  • Made with strong and high-end materials
  • Efficient blade design to blog a huge volume of air
  • Super quiet fan

Terrabloom 10” Inline Duct Fan

It delivers a high airflow of up to 1065 CFM. At the same time, it’s cost-effective.

Key Features

  • Runs optimally for a longer period
  • Ultra-quiet fan
  • A powerful CFM coverage with a low energy consumption
  1. Drain Stagnant Water

Considered the most straightforward method but usually overlooked is draining stagnant water.

The first thing, check for the presence of surface water. Surface water tends to evaporate into the atmosphere, therefore raising the humidity.

Your drainage should be checked to ensure that water is flowing. Fixing the drainage and excessive watering of the plants is not a solution.

  1. The decrease in Plant Density

Studies show that high plant density in the growing area tends to create an uneven spread of CO2 and increase humid.

Technically, with excess plant seedlings, excess transpiration is unavoidable. Therefore, more water vapor in the atmosphere. If the existing systems cannot take care of the excess humid, then it will condense on the cooler surfaces.

Why Do You Need to Control Condensation in Your Grow Room?

By now, we already know that regulating temperature and humidity levels in the grow room controls condensation.

By the time you start to see droplets of water on top of surfaces, more unnoticed damage has already happened.

Condensation creates a conducive environment for the growth of molds and mildews. Mold and decays on the plants lower their quality. Therefore, the yields will reduce significantly.

If condensation is in the extreme levels, your plants will be suffocated,

If you were a concern, “why there is condensation in your grow room?” – Then I am sure you have got the answer.

Final Verdict

Don’t panic when you see signs of condensation in your grow room. You can adopt the simple techniques discussed above. The methods are considered to be cost-effective.

To get the best result, consider implementing a combination of the methods detailed in the article. If you are looking for a permanent solution, then installing an AC compatible with your room is perfect.

Click on the items recommended in the article and check their prices on Amazon.