How To Raise & Lower Humidity In A Grow Tent?

Curious to learn how to raise & lower humidity in a grow tent? We got you!

One of the reasons why grow tents are so awesome is that you can regulate various factors to make your plants grow as you wish.


Of course, this isn’t possible outside your grow tent, where things like light exposure, humidity, and temperature, are all at the mercy of the environment and weather.

However, controlling every factor inside a grow tent isn’t always easy: one of the most complicated aspects is, for example, humidity, and that’s why we’d like to focus on just that.

In this article, you are about to find out how to raise, and lower humidity in a grow tent.

Read: How Do We Review A Tent?

Also Read: How To Clean Your Tent?

How To Raise The Humidity in a Grow Tent?

How to raise the humidity in a grow tent

There are various ways of increasing humidity inside a grow tent: if you try one on this list and it doesn’t work or isn’t enough, you can move on to the next one.

You don’t need to pick only one. If you need to increase the humidity level by a lot, you can use multiple methods to enhance the effects.

1. Reduce Ventilation

If you want to increase the humidity levels, you can reduce the ventilation on your grow tent, and this will make the humidity level rise.

2. Add More Plants

As you may know, plants transpire: they excrete water vapor during their vital natural cycle. If you need more humidity, just adding more plants should make the difference.

3. Hang Wet Towels

Another way of adding humidity is adding water or water vapor sources inside the tent. The easiest way is to place a wet towel inside the tent.

4. Reduce The Temperature

If you can, you can also try to reduce the temperature inside your grow tent. However, make sure that the lower temperature won’t damage the health of your plants.

Read: What Are Tent Footprints?

Also Read: How To Insulate A Tent For Winter Camping?

How To Reduce The Humidity In A Grow Tent?

Decrease Watering

1. Decrease Watering

If you need to lower the humidity inside your grow tent, you need to reduce the amount of water inside the tent.

If you can, reduce the watering. Make sure, however, that your plants are provided with just the right amount of water they need.

However, it’s important to say that if you notice that there is the need to reduce the humidity level, then the reason for it (for too high a humidity level) is just over-watering. 

2. Increase Ventilation

Another way of reducing humidity in your tent is by increasing ventilation.

You can do it by opening “windows” or holes in your tent to make the air circulate more easily and effectively, but you could also use a venting fan.

3. Air Conditioner

When the humidity is just too high, you could also use an air conditioner. However, this is a method usually used in very large grow tents and by professionals.

If you have a home grow tent, then a venting fan should be more than enough to adjust the humidity levels of your grow tent.

Read: How To Get Rid Of Tent Worms?

Read: How To Heat A Tent Without Electricity?

How High Humidity In Grow Tents Can Affect Your Plants?

You might have heard that plants love high humidity and while that is true, overdoing it can cause problems for your plants too.

Here are some of the negative effects of very high humidity in grow tents:

  • Too much humidity in the soil can lead to root rot.
  •  It can cause white mold, which does not let the leaves of the plant to soak up light, air, and other nutrients from the air properly.
  •  It can lead to unwanted microbiological growth.
  •  Slow down the nutrient uptake of your plants.
  •  It can cause hindrances in the process of transpiration.
  •  Make your plants more prone to diseases, pests, and fungi.
  •  Affects plant yield.

What is The Ideal Humidity Level For a Grow Tent?

Different types of plants in different stages of their life require varying levels of humidity.

For example, Seedlings require 70%-75% humidity levels because they need more time for their root system to develop, which makes them rely more on their leaves for water.

For this reason, grow tents have humidity domes or propagation trays to build more moisture.

Flowering plants, on the other hand, need a 40%-50% humidity level, and Vegging plants require 50%-70% humidity because they are able to absorb water from their roots and leaves.

When your plants are in the stage of harvesting or drying, then keeping a humuidity level of 30-40% is ideal. This will ensure the buds do not dry out fast.

StageHumidity level
Germination/Cloning75-85% Rh
Vegetation 40-60% Rh
Flowering 35-50% Rh
Harvesting/Drying30-40% Rh

Ways to Lower Humidity in a Grow tent

Ways to Lower Humidity in a  Grow tent

If you have created an unhealthy humidity level in your grow tent, then here are some proven ways in which you can lower the humidity levels.

1. Use a Dehumidifier

Dehumidifiers are extremely useful in getting rid of the excess moisture from the air, but they will add to your cost of investment.

The dehumidifier that you choose to purchase should be able to absorb the same level of water that your cultivated plants absorb daily.

You should place the dehumidifier in the center of the room to work effectively and reach all plants.

2. Get Rid of Stagnant Water

Your grow tent should have enough room for excess water to drain out.

Letting puddles of water form around your plants makes a home for bacteria and fungi to flourish, leading your plants to underperform or even die. So ensure your grow tent has a good drainage system.

3. Avoid overwatering

Overwatering your plants will obviously cause more humidity levels, and this could lead to root rot, growth of bacteria, pests, etc.

If the soil of your plant is too soggy, then it is a sign you are overwatering. So make sure you avoid doing this.

4. Plant Density

Because of the release of carbon dioxide from your plants, the temperature of your grow tent increases naturally. As a result, the humidity and moisture level increases.

If you add more plants to your tent, then it can result in preventing other plants from getting carbon dioxide and fresh air to operate.

5. Increase Insulation

To keep the humidity level in your grow tent in check, you need to provide proper insulation. For this, you can use foam insulation.

This will create a thick barrier between your grow tent and the external environment.

6. Improve Ventilation

Proper ventilation is required to maintain the right humidity inside the grow tent.

To improve ventilation, you can place a fan inside the tent or create holes in the tent so that the excess moisture has an outlet to pass from.

7. Get an Air Conditioner

An Air Conditioner uses gas and compression to pull the excess heat out of the tent.

It also helps in creating condensation, which is very effective in removing excess moisture from the air.

Hence, you can buy an AC of the appropriate size to ensure a good humidity level in the tent.

8. Using Absorbent Soil

Soil that is able to keep the water underneath it is considered ideal for growing plants in a grow tent. For example, You can use sandy soil, which is affordable and effective.

You can also go for perlite. The only thing is to avoid soil that creates dampness for the plant.

9. Defoliating Your Plants

This tip is great for you if you want to control the humidity levels without spending anything at all. The more leaves your plants have, the more they will create moisture.

Hence, you should defoliate your plants so that a good level of humidity can be maintained.

The Ideal Grow Room Conditions 

Wrapping Up

Having the right level of humidity is the key to the right growth and health of your plants.

If your grow tent has an unhealthy amount of humidity levels, then there are all kinds of ways to deal with this. We hope you found this article useful.


Will adding a bucket or bowl of water inside my grow tent raise humidity?

Humidity is essentially water vapor. So adding a bucket of water or bowl can help in increasing the moisture level in the air.

For how long should I run my fan in grow tent?

We recommend you run the fan all time during the day and switch it off when it gets dark.

For how long should I put the LED lights on in the grow tent?

Putting them on for 12-18 hours in a day is considered ideal for the growth of plants in a growth tent.

NPC Overall Rating

Leave a Comment