How To Control Humidity In Grow Tent: 5 Simple Things!

In this post, you will see how to control humidity in grow tent.

Occasionally, we like to cover special subjects, like this one. Recently, we looked at how to control humidity in an incubator, to get those eggs to hatch just right!

In the same spirit, we will show you how to tame runaway growing tent humidity, to increase your plant yield.

If you like growing things, a grow tent is a good investment because it helps you grow your favorite plants and herbs under a controlled environment.

But a grow tent is not all glory. Because it is covered up, some difficulties can come up. For instance, the humidity could rise tremendously and so could the temperature.

When there is too much moisture in the air, your plants can develop serious issues. For instance, they can start rotting at the bud. High humidity also hampers the growth of your plants.

Just the same way that high humidity causes mold in the indoor spaces, it can do the same to your grow tent and plants.

If you let the humidity run too high, fungal attack will cause serious problems with your plants. In return, this affects your yield tremendously.

How to control temperature and humidity in grow tent

In line with knowing how to control the grow tent humidity levels, you also need to know how to control the temperature.

There is a relationship between humidity and temperature. When the temperature rises, the air gets warmer. Warm air holds more water (higher relative humidity level) than cold air.

In the grow tent, temperatures are usually high. Thus, the humidity also seems to rise. Generally, the recommendation is to keep the grow tent humidity level at 70 percent.

In another article, we looked at the ideal room temperature for the human body. If humans have an ideal room temperature need, also, plants in a grow tent do require an optimum temperature for growth.

Generally, it is recommended that you keep the grow tent at 75 to 85 degrees Fahrenheit/23 to 29.4 degrees Celsius.

Most plants do well within this temperature and humidity range. Of course, it is best to know your particular plants’ temperature and humidity needs so that you can adjust these conditions accordingly.

Increase humidity in grow tent

When you see the terms “controlling humidity” what pops into mind is the need to lower the humidity level.

However, it works both ways! If the grow tent has too low humidity, there can be some serious repercussions.

When you see the low humidity symptoms in plants, you will know it is time to increase the humidity in your grow tent. These include browning of the leaves, wilting leaves, curling leaves and stunted growth.

To remove all doubt from your mind, you can check the humidity level using a hygrometer. If it is below 70 percent, you need to increase it.

How to maintain humidity in grow tent: 5 Sure Ways

High humidity inside your grow tent does not have to fluster you. There are simple things that you can do to help lower the humidity.

But controlling humidity does not only mean lowering it. You can also increase it when the need arises. Keep reading to see the few vital ways of controlling humidity in grow room:

1. Use a dehumidifier and/or humidifier

The important thing here is to know when to use a dehumidifier or humidifier. We have already said that the grow room humidity should not exceed 70 percent.

If it rises higher than that, run the dehumidifier. It will lower it to the appropriate level. What is more, you can use the water from the dehumidifier to water plants. This sure does seem like a win-win situation.

You can use a portable dehumidifier with a drain hose so that you don’t have to keep emptying the tank. You can read our review of the 70-pint Frigidaire dehumidifier to see why it would be appropriate for your grow tent.

Before you can buy a dehumidifier, measure the size of the grow room. Dehumidifiers have a space rating. If it is rated for 260 square feet, do not use it in a space bigger than that.

If the humidity goes too low, it is not good for your indoor plants since it could make them lose too much water to the surrounding.

To increase the grow tent humidity levels, use a humidifier. It is going to release cool mist into the air, increasing the level of moisture content in the air to 70 percent.

For both humidifier and dehumidifier, ensure that they have start/stop functions. That way, whether lowering or increasing indoor humidity, when the appropriate level is attained, they switch off automatically.

2. Install an exhaust fan system in the ventilation

Enhancing the ventilation system of your grow room and tent can help a great deal. An exhaust fan system can help remove the humid air from the tent.

The good thing is that today you can find an exhaust system that you can set so that it turns on automatically when the air humidity reaches a certain level.

It is designed with an exhaust vent at the top through which the humid air can escape. It also has an intake at the bottom that lets in fresh, drier air from the outside.

Image of grow room temperature and humidity control

You can also increase the ventilation in your grow tent. In another article, we saw how increasing ventilation in a utility room can help to control humidity.

When the air from outside is drier, you can close the vents to prevent the humid air from escaping or to keep the dry air outside.

3. Control the temperature – 75 to 85°F/23.8 to 29.4°C

The temperature directly affects the humidity of your grow tent. Warm air holds more moisture than cold air. Thus, if you do not control the temperature in the grow room, it will be hard to control the humidity.

To control the temperature, you need to invest in a good air conditioner for the grow tent. Today, air conditioners come with a thermostat.

It switches the air conditioner off and on as need be. When the set temperature level is attained, it turns off automatically. If the temperature rises higher than it should be, it turns on.

When buying an air conditioner, do make sure you get the right sized one. If you make it too large, it might make the temperature change too suddenly. This can affect the plants. Thus, you want one rated for your tent size. The temperature control should be gradual.

You should also take care to use the right grow lights. If they are too bright, and the bulbs are not of the best quality, they can raise the indoor temperature of the grow room.

The right temperature for a grow tent is between 75-85 degrees Fahrenheit/23.8 to 29.4 degrees Celsius. This can differ from plant to plant.

However, assuming this range is recommended for your plants, set the thermostat such that when it rises above 29 degrees Celsius, the AC switches on automatically. When it (temperature) drops to 24 degrees Celsius, the AC turns off automatically.

4. Improve air circulation to control humidity in grow tent

Air circulation is another important factor for humidity control. By increasing air flow, we mean you should have the air moving in all directions, something that you can do with the help of fans.

Most people think that wall fans are enough, but they are not! You also need floor fans so that the air movement can come from all directions.

The importance of blowing the air around the room is that the humid air is lighter in weight, so it floats above the drier air.

The drier air contains carbon dioxide, which your plants need. When the air with carbon dioxide is closer to the ground, the plants can access it easily.

When you have floor fans, they can help to blow the humid air to the ceiling of the growing tent.

5. Do not over-water your plants

When you are growing your plants in a controlled environment, you need to know that any excess water will certainly find its way to the air. It will contribute to increasing the humidity in the air.

One of the ways to control humidity in your growing room is to make sure there is no stagnant water.

Many growers wrongly think that feeding the plants more water when the soil is dry is good. The plants can only take what they need and the rest evaporates to the air, increasing humidity.

Increase the drainage for your grow tent so that there is not much water lurking around the plants.

Also, adhere to the recommended quantity of water that you should feed your plants daily, weekly or on whatever schedule you use.

How to Control Humidity in Grow Tent FAQ

You really need to watch the level of humidity in grow room. If you still have your doubts after reading the information, here, we bring you a few frequently asked questions and their answers.

How do I lower the humidity in my grow room?

  • Buy a good size dehumidifier to remove the extra humidity from the grow tent
  • Enhance ventilation and air circulation using an exhaust system
  • Use floor fans to blow the air upwards – humid air is lighter so it floats
  • Use the recommended amount of water to water your plants
  • Space the plants out

How can I lower the humidity in my grow room at night?

The best way to deal with humidity in the growing room during the day or during the night is to remove it.

While heating the air might help, well, it does not remove the humidity. Thus, run a dehumidifier in your room, let it collect the extra moisture from the air. When it attains the desired humidity level, it will switch off automatically.

How do you automatically control humidity in a grow tent?

If your plants are releasing too much moisture into the air inside the growing tent, you can do something about it. Get a dehumidifier that comes with accessories to connect it to a drain hose.

The dehumidifier should also have a humidistat so that when the humidity is higher than the set level, it switches on automatically.

If it reaches the desired level, it switches off automatically. Since you do not need to empty the bucket, you can be sure your plants are safe even when you are traveling.

Do fans lower humidity in grow tent?

Install fans on the wall and on the floor. By whipping the air in the grow room from all directions, it helps to push the humid air outside and pull in drier air. If you have the wall fans alone, they will not help enough.

Is 70 percent humidity too high for flowering?

Depending on the plant type and its needs, in the flowering stage, the humidity level should be lowered to between 30 and 50%. On the other stages of growth, the recommended growing tent humidity level is 70%.

What happens if humidity is too high in flowering?

If you keep the humidity level above 40 to 50% in the flowering stage, the flowers can develop mold. Poor flowering also means poor yield. Overall, this will ruin the whole plant since it won’t be productive.

How can I raise the humidity in my grow room without a humidifier?

The ways to raise humidity naturally in the growing tent include using a sponge soaked in water. You can also hang a wet towel or place a water pan in the center of the room. This is going to raise the humidity appropriately.

What should the temp and humidity be in a grow room?

the recommended temperature level is 70 to 78 degrees Fahrenheit. However, find out what is best for your plant types. The recommended humidity level for grow room is anywhere from 45% to 70%.

Image of temperature and humidity in grow tent

Wrapping Up on How To Control Humidity in Grow Tent

You have seen how to lower humidity in grow tent without dehumidifier. You have also seen when to use a dehumidifier to bring the level of air moisture down.

It is important to have a thermometer and a hygrometer to always stay on top of your temperature and humidity levels.

Low humidity level in the grow room is only good at the flowering stage. It is recommended that you keep it at 30 to 50% depending on the plant. During the other growth stages, keep the humidity in the grow room at 70%.

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