13 Ways To Increase Humidity In Grow Tent | Step by Step

Planting seedlings outside is very common. But how do you control the outside temperature?

Or how do you make the climate according to the needs of your plants?

Is this possible?

These are the most asking questions from professionals and home gardeners.

Don’t Worry!

Here in this article we will solve all your questions and give solutions to them.

First, you have to know that you can raise plants inside the home and set the temperature yourself as you want.

Yes… you can do that by using a grow tent. It’s very simple….

Just by knowing how to control humidity levels, it is possible to grow plants inside in the right atmosphere.

So, it is important to know how to increase humidity in a grow tent?

There are thirteen easy ways that will help in moderating humidity in a grow tent. Some of them are costly and some are cheap. You can select your own. It is easy to increase humidity by a humidifier or some other devices that are also found at home. A hygrometer may also prove your best friend to increase the humidity level.

There is a need to know about what is humidity?

Simply, humidity is the amount of water vapors that are found in the air. You can measure humidity in three ways: absolute, relative, and specific.

Low humidity causes the slow growth and death of plants. So, it is very important to increase humidity for the health of young plants.

Here we explore different methods of increasing moisture or humidity in a grow tent. Hopefully, you may get an advantage by following it.

How To Increase Humidity In A Grow Tent

Do you want to plant seeds inside? 

If yes…

You must have big advantages while planting in a grow tent as there are more ways to control the environment completely. It is easy to provide your plants with perfect conditions to increase their growth level. 

When plants come to stuffiness, the ideal level of humidity depends upon the stages of growth. Such as at seedling humidity will be 70%, vegging 50% to 60%, and bloom 40% to 50%.

Naturally, there comes a time when you need to increase the humidity of the grow tent. So, here are the 13 easiest ways to do that:

13 Easy Ways To Raise Humidity In Grow Tent

You can increase the humidity level in your tent by following the 13 ways given below. Let’s discuss them in detail.

  1. Combine Young Plants

It is said that large plants take light, food, and air from small plants. On the other hand, the relative humidity will rise in a grow tent when you start adding large plants. Because they produce more humidity in a grow tent.

When big plants inhale, they release carbon dioxide and water vapor to feed their small counterparts.

So, there is no need to overcrowd the large plants to get air, light, and nutrients for growing plants. After boasting bigger leaves, large plants can discharge more water, and hence growing plants can use these water vapors. 

  1. Use A Humidifier Inside Grow Room

You can buy a humidifier for the best investment. It is used to elevate humidity levels in a grow tent as it extricates the cool mist. It is also helpful for the growth of plants. 

The moisture level of the humidifier should be at least 50% to 65% depending upon the size of your grow tent.

If your grow tent has two shelves, top and bottom, place the humidifier on the bottom. In this way, it won’t spray mist directly on the grow lights.

Remember that you must control the level of the humidifier because full power could cause too much moisture in the air.

It is recommended to buy a humidifier that can take at least six gallons of water at a time. It has also a long-running power.

  1. Make Use Of Propagators

Seedlings germinate naturally themselves, but you can get more chances of success to grow plants. It is possible only if you increase humidity in your grow tent by using propagators.

Do you know how indoor growers protect their seedlings and cuttings? It is possible if you notice them in propagators.

You can use propagators such as Early Grow Urban Planter Box or a sheet of polyethylene and a glass cover.

They can keep the high level of humidity in your grow tent. It also ensures that seedlings will not stress their root systems when they are developing and growing.

  1. Make Your Own Propagation Set Up

You can build your own propagation set up with the help of two things. You need to buy an adjustable extractor with a built-in thermostat. It can control the temperature by pulling out the air.

Then place a bucket of water on the top of the grow tent. This water is transported into a humidifier with the help of a hosepipe.

This is a very suitable method for cuttings and seedlings. When a cool-mist extract inside the grows tent, the humidifier will raise humidity. 

  1. Set Trays of Water Near Passive Air Holes

There is another obvious option. Take a wet towel or a pan of water, hang the towel, or put the water pan near air intakes. It will mist the walls down and humidity will rise. Because of it a large amount of moisture absorbs in the air.

However, on the other hand, a towel has the ability to dry up fast. You have to make it wet from time to time.

You can also use trays of water instead of a wet towel or a water pan.

There is a complete guiding video of installing flood trays.

  1. Eliminate Fluorescent Lights

Mostly, common solutions are missed. There is another way. You can reduce the temperature by removing half of your lights.

Don’t worry!

it will not create trouble for your baby plants until they don’t need much light.

This video will guide you to set fluorescent lights according to need.

  1. Set Minimum Setting of  Extraction Fan

It is essential for a grow tent to vent because it will help you to control or manage the humidity for your plants. Proper ventilation makes sure the exchange of air in and out.

Moreover, fans are helpful to circulate the air well and distribute it to your growing plants. As a result, you can save your plants from fungi and bacteria from increasing because of proper air circulation.

Normally, you can set your fans at a moderate speed to observe moisture at different stages of growing plants.

Similarly, if you set the fan at high speed, it will prevent the water vapors from settling on the surface of plants’ leaves. You can also raise the humidity by reducing the fan speed by 60%.

  1. Use Water Spray Bottle

Do you want to know about another easy way to increase humidity? 

All of us have a spray bottle at home or in a garden. You can spray water on the walls of the grow tent with its help. 

Repeat this process every morning and evening.

  1. Lower The Temperature Around

How to cool a grow tent to raise water vapor?

Learning about it is the know-how for indoor gardeners. But it becomes a challenging task when temperature regulation is involved in it.

It must be noticed that cold air sinks in the bottom due to its high density as compared to hot air. The air becomes moist and has a large amount of water vapor at a lower temperature. 

Similarly, the dropping intensity of ultraviolet light is also helpful to increase water vapor. But it may be possible only if it is enough to facilitate the water evaporation.

  1. Choose a Swamp Cooler

A swamp cooler is also another way to lower the temperature of the grow tent. It is also helpful as it cools down the air and increases the level of humidity.

It works only in certain conditions. As it operates in low humidity and high temperature.

You can buy Honeywell portable evaporative coolers that are suitable for your grow tent. 

  1. Stock Water Resources

Stocking water is the cheapest way to increase humidity in a grow tent.  In this way, you can also distribute water according to the needs of plants.

Water trays also work well when placing near air holes. You can also put damp sponges next to growing trays. The heat of a growing lamp or an air conditioning system evaporates the water in the sponges and increases humidity in the grow tent.

  1. Reduce Temperature By Using An Air Conditioner

Many gardeners use air conditioner’s temperature to attain high humidity in their grow tent. They may also increase or decrease the temperature of the heater. 

This method could be costly, but if you have no other option, you can use it.

  1. Cover Young Plants With Glass or Plastic Tomb

It is important to cover young plants while increasing humidity. For this purpose, you can use plastic wrap or a glass dome. Gently cover them to give them their own micro-climate in the grow tent. 

In this way, they can trap and revive their moisture for the long term as they have assessed to light. 

For large plants, you can use bell cloches as an alternative.

Note: There is an easy solution. You can get a complete Grow Tent Kit instead of buying each device separately.

Right Humidity Level

Do you want to know about the correct level of humidity? It’s very important to have knowledge about it. Because most of us get damages in our indoor plants due to lack of info.

Just like temperature, plants also need different humidity levels in different stages. Let’s discuss them:

  • Clones or Seedlings: They need at least 70% to 75% humidity because it is the time to grow the root system. As you know young plants need a lot of moisture in the air. This can be achieved by using propagation trays or humidity domes. That will increase the success rate of clones to root.
  • Vegging Plants: 50% to 70% humidity is best for vegging plants. Now seedlings have developed their roots. However, they need the help of leaves to absorb moisture. Hence low humidity level is the main cause of slow growth.
  • Flowering Plants: At this stage, plants grew up. Now their humidity level decreases to 40% to 50%. If you maintain lower humidity, you can prevent the fungus from forming.
  • Harvesting: Usually, in a grow tent, harvesting requires 45% to 50% humidity. It will protect your harvest from becoming harsh and rigid.

How To Measure Humidity in a Grow Tent

Measuring the humidity level in your grow tent is very important. Do you know why?

A little mistake in the level of humidity though high or low will destroy your efforts and hard work. So, be careful!

You can measure the relative humidity by using a hygrometer or a device that has features of a humidistat. A hygrometer is used to monitor the humidity in the space. On the other hand, a humidistat device can help to regulate the humidity in a room.

If you want to know the humidity of the grow tent at a glance, a hygrometer is best for it. To check the change of humidity level with time, it is good to use a temperature-humidity monitor.

increase humidity in grow tent


In the end, we may conclude that humidity at high levels in your grow tent is essential for the healthy growth of your plants.

Keep in mind that controlling the level of humidity also means to view many other features of indoor gardening such as temperature, light, and ventilation.

All the options mentioned above are economical and you are free to select a way that is suitable for the conditions of your grow tent.

Generally, high temperatures will make your environment humid. On the other hand, a cool temperature may cause less moisture in the air.

So, you can get experience by using different methods to increase humidity. And that’s how you will surely discover what works best.

Lisa Marshall

Hi, This is Lisa Marshall. Lisa has been working with farmers for over thirteen years. It is his passion, hobby and profession. To facilitate other gardeners from her experience, she has decided to start this website to share her gardening experience with her plant lovers.

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