How to Increase Humidity in Grow Tent?

Indoor gardening is gaining a lot of grounds worldwide and this is attributed to the fact that you can regulate humidity inside a grow tent. So, what is humidity? Why is it so important to plants that it has to be regulated and in particular increased? Personally, when I started this business I knew nothing about how to increase humidity in grow tent and this explains why my plants didn’t do well as I had anticipated.

Humidity is the amount of water vapor held in the air. Relative humidity is measured using a hygrometer and if you are a serious indoor gardener, this equipment is mandatory.

Why Humidity Regulation Is Important In Grow Tent?

Before analyzing the various ways on how to increase humidity in grow tent, it is important to first understand why humidity is essential for growth of plants. Generally, plants take up water through the roots but, if the general surroundings have a rather low humidity these plants will end up losing the moisture through the stomata.

Dry and low humidity creates HPV (high vapor pressure) where the plants are forced to lose water to the surrounding environments. Other than making plants to lose moisture that would have otherwise be retained in the plant, dry low humidity is also a perfect environment for bugs and pathogenic mods.

How to Increase Humidity in Grow Tent?

If you want your plants to do well, it all comes to ensuring that the humidity in the grow tent is ideal. The recommended relative humidity for most plants is 60% which is not all that simple to achieve especially if you don’t know how to go about it or you are simply a first-time gardener.

You have come to the right place I was also in your shoes a few years back and if then I know the various ways on how to increase humidity in a grow tent, things would have been much easier for me.

The following is a list of ways in which you can increase humidity in indoor gardening;

  • Lower the surrounding temperatures
  • Increase water sources
  • Get a cheap humidifier
  • Use a fan
  • Mix both young and mature plants

1. Lower the Surrounding Temperatures

Basic science states that cool air is denser than hot air and this settles at the bottom. Earlier, humidity was defined as the ability of air to hold water in form of vapor. When the inside of a grow tent is too hot, the air loses its ability to retain water and this is reflected on a drop in humidity.

Anyone who knows a thing or two on the basics of indoor gardening will tell that dry and hot air is a no, no if you want your plants to do well in a grow tent. One of the ways in which you can increase the ability of air to hold water is by lowering the surrounding temperatures.

By so doing, you will be increasing the capacity of moisture held in the air and the humidity levels will increase. Temperatures in a grow tent can be lowered either by regulating it on the heat supplier or reducing the intensity of the ultraviolet light in the tent.

2. Increase Water Sources

Low humidity simply means that the air is moisture deficient. As we all know moisture simply means water, right? A rather simple way to raise the humidity in the grow tent would be by increasing the water sources. And, there are various ways on how you can go about this.

You can either place saturated sponges on growing trays, hang wet towels or simply place a basin of water in several spots in your grow tent. All the three have the same effect, that is, when water is heated it evaporates.

Some would argue, where will the water get heat from? Basically, the heat will be from the heat supplier in your grow tent. This doesn’t call for you to manually heat the water (just to make things clear). It is this moisture that is retained by the air to increase the humidity.

3. Get a Humidifier

This one is going to require you to dig into your pockets but is a small price to pay to ensure that your plant grows under the ideal conditions. After all, this is not something that you have to purchase every now and then. You can get a humidifier at discounted prices on Amazon or any other leading online store. So, how does a humidifier work?

Personally, before I purchased the gadget I knew nothing about it. I had to consult the manual in virtually anything. Basically, a humidifier is fed with water that is then heated to evaporation.

This vapor is then allowed to escape into the surrounding environment and in the process raise the humidity of a grow tent. This process should, however, be controlled to prevent releasing too much moisture into the grow tent which has its own set of drawbacks.

The gadget is electric and for efficiency, you should connect it to a dehumidifier. This was you will be in a position to control humidity levels in your grow tent.

This is a product for you to refer for your grow room:

4. Use a Fan

When I was venturing into the business, using a fan to increase humidity in a grow tent hit me with surprise. Then I couldn’t find any significant relationship between humidity and a fan. The truth is, fans are crucial when it comes to regulating humidity in indoor gardening. 

Having fans in a grow tent ensures that there is smooth and even circulation of air to all the plants. This also helps cool the air and in the process increase its ability to retain moisture.

However, the fan should not be set at a first pace since this might end up drying the air rather than making it most and cool.

You can refer to this product:

5. Mix Both Young and Mature Plants

Mix Both Young and Mature Plants

Most people are of the argument that, mature plants can be mixed with young plants since they will end up taking more air in the process starving the young plants. Well, there is some element of truth in this but, if you have an effective supply of air then you should consider mixing both young and mature plants as a way to increase humidity in the grow tent.

Mature plants have a more elaborate and fully developed root system that takes in water from the soil. This water is then lost through the stomata when breathing and this increases moisture in growth tent.

The only thing you should put into consideration when doing this avoiding overcrowding. If it gets overcrowded the plants won’t do well and this is every gardener's nightmare.


It is my hope that you found this post on how to increase humidity in grows tent useful. Personally, when I was starting my gardening business I knew little to nothing about raising humidity.

Honestly, I would have benefited with such useful information. This information is now at your disposal and I’m certain that your business will now be a success. If you found the article useful kindly share it with a friend or two and enlighten them on how they can raise the humidity in a grow tent.

7 thoughts on “How to Increase Humidity in Grow Tent?”

  1. The relative humidity of your grow area depends mostly on where you live, and how you’ve chosen to construct your grow area. Many growers struggle with lowering their humidity, because the mass of leaves and vegetation in a small grow area tends to cause the humidity to go up.

    • I only need enough yield to supply my husband and i with a big enough harvest to last until next harvest which is usually around 4-5 oz. We have been growing with CFLs in our closet and i wanna make sure we use our money wisely when purchasing a tent.

    • OK, so now we know why we should keep the relative humidity up in your grow tent, let’s discuss how we increase the humidity in your grow tent.

  2. Hey guys,

    I cannot seem to get my tent temp up or humidity up to optimum level even with a heater inside and a humidifier. Both are on full now and struggling to get to 50% and temp above 24c. Any advice greatly appreciated. The external temp is 22c.


  3. Your description of humidity and how it is related to temperature is a little misleading. When you say “the inside of a grow tent is too hot, the air loses its ability to retain water, and this is reflected in a drop in humidity.” It is not precisely correct.

    Temperature affects relative humidity. The relative humidity is a measure of the amount of water vapour in the air as a percentage of the total amount the air can potentially hold. As the temperature of the air increases, the amount of vapour the air can hold increases. So, if the amount of vapour remains the same, but the maximum amount of vapour the air can hold goes up, the relative humidity (total vapour vs maximum vapour) goes down.

    So as temperature increases, the relative humidity goes down. As the temperature goes down, the relative humidity goes up.

    As a side note, this is why it rains too. When the air is supersaturated, (i.e. close to 100% relative humidity) and it is cooled (by being blown up to higher altitudes), it results in too much vapour in the air for it to hold. The vapour condenses and falls to the ground as rain.

  4. Hi guys,
    I’m having problems increasing the humidity in my grow room. If I lower the temperature it will then be too cold in the room and still the humidity is low. I have a humidifier as well and still the humidity is low. What else can I do? Should I have 2 humidifiers?
    Also, and I know this may seem like a silly question but I’m new to all of this, but re food, is grow food given before bloom?

    Really appreciate any advise


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