12 Ways on Raising Humidity in Grow Tent

Have you seen your plants asking for water? Have you seen your plant’s leaves twisting upwards? There might be chances that it is too dry in your grow tent. 

Every indoor grower knows that temperature and humidity levels are the key factors to giving your plants a decent environment to grow. Knowing how to control and increase the relative humidity in a grow tent is something that indoor growers should learn.

Humidity levels of around 45% to 75% are great for growing plants. In any case, if your grow tent is merely at 20% to 40%, you must take action, or you might put your plants in danger.

Low humidity within a grow tent causes hindered growth and poor development of your plant. It could prompt moistness and lower yields in the long run.

This is the reason you should bring the humidity up in a grow tent. It can be accomplished by replying to a humidifier or essential tips and tricks using materials found in your home.

Let us make you acquainted with some basics of humidity when it comes to a grow tent.

Humidity is the amount of water vapour held up in the air. There are three different ways to measure the amount of humidity: absolute, relative, and specific. You can also measure humidity using a hygrometer, which pretty much is your homie when it comes to gardening.

Since we are into indoor gardening now, we will be focusing on the relative humidity. RH measures how much water is in the air all around versus the maximum amount of water held in the air at specific temperatures.

Plants can flourish at different relative humidity levels. However, it would, in any case, rely upon the temperature of your grow tent. Keep in mind, the hotter the air, the more water vapour it can hold.

What is Relative Humidity?

The relative humidity is a rate that shows you the ratio of current moisture content and the maximum possible moisture content of a specific amount of air. 

The formula to measure Relative Humidity (RH) is:


The higher the grow room humidity rate is, the more vapours can be generated in the air, and the more humid your grow room feels. And the other way around for lower humidity rate.

There are other active impacts of environmental factors like:

  • Temperature: RH goes up as temperature rises.
  • Light: RH goes up as light turns out to be more intense(bright).
  • Ventilation: RH goes up as air ventilation is low.
  • Irrigation: RH goes up as irrigation(water flow) increases.

RH and Other Environmental Factors

Humidity and Temperature 

Humidity is indirectly related to the temperature of your Grow tent. When the temperature rises, the air’s capacity to hold the vapour decreases. Hence, you will have a low Relative Humidity, where the temperature is higher than cooler areas like the roof or vent openings.

Humidity and Light

Light does not directly affect the humidity of your grow tent. However, the basic grow lights emit a lot of heat, which impacts the humidity of the tent. If you do not make sure that you have an appropriate air-cooling system, it will affect the humidity of your grow room.

Humidity and Ventilation 

Ventilation also affects the air inflow, and outflow of the grow tent. Accordingly, excessive ventilation will bring on faster air circulation, which will not let the grow room become humid enough. 

Then again, slow ventilation will trap the air and the humidity and temperature underneath it. 

Accordingly, neither quick ventilation nor too slow ventilation is helpful in growing a good quality yield.

How do you know if your Relative Humidity levels are appropriate?

Measuring the Relative Humidity In Grow Room 

The most ideal approach to measure your grow room humidity is to use a grow room moisture meter(hygrometer). There are many different models available on the internet, and a lot of them are electric thermo-hygrometer combos.

Notwithstanding, there are two types of electric thermo-hygrometer combos available. In case you are wondering about them, here is how they work:

Resistive Electric Hygrometer 

Power goes through a ceramic substance that is in the air. With the increased humidity(water vapour), the ceramic shrinks, and that modifies its resistance. Also, the level of change is transformed into a change in humidity.

Capacitive Electric Hygrometer 

It uses a capacitor (two plates with air in the between) kind of arrangement. The humidity of the air between the metal plates characterizes how much charge these plates can hold. Accordingly, the level of humidity comes out in numeric value.

The Best Temperatures For An Indoor Grow Room Or Grow Tent:

how to increase humidity in grow tent

Ideal grow tent temperature changes as per the phases of vegetation; as we have mentioned before, temperature and humidity are directly related. 

Indoor growers usually put their money into a digital thermometer and hygrometer to help them with the following readouts.

  • Clones or seedlings incline toward 74-78 degrees Fahrenheit.
  • Vegging plants incline toward 70-78 degrees Fahrenheit.
  • Flowering plants favour 88-75 degrees Fahrenheit.
  • The harvesting phase usually requires 65-74 degrees Fahrenheit.

How Grow Tents And Relative Humidity Can Help You Grow Plants?

raising humidity in grow tent

Using a grow tent, and a climate controller gives you more power over your plant’s growing environment. Also, it will help you with controlling the light cycles

Besides, increasing or decreasing the relative humidity levels is more accessible in a grow tent with a small air volume. 

A grow tent permits you to deal with many plant varieties all through the year paying very little heed to the season, weather conditions, and the environment. It also gives a suitable environment for plants to retain supplements.

Your grow tent will support forestalling potentially harmful components like insects, buildup, molds, and bugs from damaging your plants. 

Be that as it may, these would all actually rely upon the overall humidity of your grow tent. It is the reason why you should learn about different methods by how you can raise humidity levels in your grow tent or grow room.

Best 12 Ways to Increase Humidity in Grow Tent

Use A Humidifier In Your Grow Room

how to raise humidity in grow tent

Getting your hands on a humidifier can be the best investment you could make. A humidifier supports increased humidity levels in a grow tent by removing the cool mist, potentially damaging your developing plants. 

If your grow tent has a top and base shelf, place the humidifier on the base part so it will not directly spray mist on the grow lights

In any case, you must also keep in mind that never ever leave your humidifier on a total power mode in a closed space as it might cause too much moisture in the air. ​

We recommend buying a humidifier with an in-built humidistat, which lets the machine automatically stop or cut in as per your ideal moisture settings. 

Also, buy a humidifier that can store up to six gallons of water at a time and can last for an extended period of time.

Decrease The Temperature By Adding An Air Conditioner To Your Tent

To get higher humidity in your grow tent, growers often increase the air conditioner’s temperature or decrease the heater’s temperature. 

All things considered, it very well may be expensive, but it is also of the few ways by which you can increase the humidity.

Stock Up On Water Sources In Your Grow Tent

how to add humidity to grow tent

Another way to increase the humidity in a grow tent is by boosting your water sources and distributing them in a like manner. We recommend placing water trays close to an air intake tube or passive air vents.

Similarly, putting damp wipes close to the growing trays so that they can function admirably. The heat from a grow light, or a cooling system can evaporate the water in the wipes, adding more humidity to your grow tent.

Always keep in mind to only use clean water to keep harmful organisms or microorganisms at bay. 

It is a given; never ever put damp wipes close to lighting materials and fans. Fans and grow lights use electricity and may have a short circuit if they interact with water.

Choose A Swamp Cooler

grow tent humidity

We recommend using a swamp cooler to bring down the temperature in your grow tent. The device helps with cooling down the air and increasing the humidity levels at the same time. 

It works when humidity is super low and the temperature is very high.

Lower The Surrounding Temperature

Figuring out how to cool a grow tent to raise water vapour is a highly challenging task for indoor growers, mainly when it includes temperature regulation.

Remember that cool air sinks at the base due to its higher density than hot air. A lower temperature generally implies that the air is somewhat moist and has a considerable amount of water vapour. 

Also, dropping the light intensity of an ultraviolet light can assist with increasing water vapour, yet just in case, it is adequate to facilitate water evaporation.

Use Water Spray Bottle

how to raise humidity in grow room

Growers usually own spray bottles, so this should not be an issue. Another simple strategy you can do is splash water on the walls of your grow tent every day and evening.

Set Your Extraction Fan Setting To Minimum

Venting a grow tent is imperative since it can help you oversee or control your plants’ relative humidity. A proper ventilation system ensures that there is an exchange of air all through your grow tent. 

Also, fans allow the air to circulate correctly and get distributed to your growing plants. Therefore, your plants can stay away from harmful microorganisms like bacteria and fungi from increasing or staying within your tent when there is a proper ventilation.

We would like to recommend using fans at a moderate speed to ration moisture at different phases of plant growth. Also, one must remember that the air might dry quickly if you use a fan at a high speed.

Also, setting fans at high speed will keep the water vapour from settling on the surface of the plant’s leaves.

In this manner, the moisture does not reach the plants, which cause dehydration and desiccation. 

You can also take a stab at reducing the number of fans to bring the humidity levels higher in your grow tent. We also recommend setting the fans at 60% to guarantee relative humidity.

Remove Half Of Your Fluorescent Lights

how to increase humidity in a grow tent

The essential solutions are often neglected. You can decrease the temperatures by removing half of your fluorescent grow lights.

Relax! The light’s intensity will not affect your plants as baby plants do not need much light as such.

Hang A Wet Towel Or Set Trays Of Water Near Passive Air Holes

One of the foolproof alternatives you can take is hanging a wet towel or putting a container of water close to air intakes, which will mist your wall down and increase the humidity. It allows a lot of moisture to be absorbed into the air. 

Be that as it may, a towel will, in general, evaporate quickly and will expect you to wet it now and again. Also, a pot or container of water will not really generate the relative humidity that you desire.

DIY Propagation Set-Up

Here’s a little experimentation that works for everyone. Get your hands on an adjustable extractor with an in-built regulator that controls the temperature by pulling out the air. 

And then, put a container of water on top of your grow tent. The water is then transported into a humidifier using a hosepipe. 

This method is compatible with seedlings and cuttings. The humidifier will bring the relative humidity up in the grow tent by removing a cool mist in the grow tent.

Use Propagators

Seedlings can naturally develop all alone, yet you can accomplish a better success rate of growing plants by bringing the humidity up in your grow tent using propagators. 

They can hold high humidity levels in your grow tent, guaranteeing your seedlings do not stress their root system while developing and growing. 

Indoor growers secure their seedlings and cuttings in propagators. 

Using a covered propagator and a polyethene or glass cover sheet will keep the seeds from drying out.

Join Mature And Young Plants

It is a typical notion that bigger plants will take the light, supplements, and air from the younger ones. 

Unexpectedly, the relative humidity in a grow tent will increase once you begin adding plants, particularly huge ones, since they breathe more and generate more relative humidity. 

At the point when your bigger plants breathe, they discharge carbon dioxide and water vapour, subsequently taking care of the smaller plants. 

Bigger plants gloat more excellent leaves and more stomata, which means they can release more water vapour after evaporation. Your smaller plants would then be able to use this water vapour. 

The key is not to stuff the bigger plants to ensure your younger plants get a decent amount of air, light, and essential nutrients.

Well, these are a few ways by which you can add humidity to your grow tent.

What are the adverse effects of low humidity in grow tents?

When it comes to plants, water acts as a coolant. They absorb a great deal of water, with about 95% going to the roots, the plant’s vascular design, and afterwards leaving through the stomata. Just about 5% goes to building new cells. 

A mix of high temperatures and dry air makes a high vapour pressure deficit between the leaves of your plants and the atmosphere. Be that as it may, plants need to exchange gases through the stomata. 

It exposes your plants to the dry conditions of the outside world. Your plants will try to get more moisture to avoid the drying effect, yet this might make it harder for plants to sustain.

Growing plants become anxious from the extra pressure factor which they apply on the roots to soak up water and ward off humidity shortage. Plant dampness also prompts stomata closing, which deprives the plant of getting more water. 

Lower levels of humidity force the roots of the plants to take a lot of water. But, it includes excess supplements that could burn the tips of the leaves. 

The lack of humidity also indicates the chance of plant drying up, where the plant becomes exposed to scourges by insects like moulds, fine white mildew, and spider mites.

Why is keeping a check on the humidity levels of a grow room vital?

For people who are starting off now, high humidity could sound startling. Take it from experienced indoor growers. We already learned how high humidity levels in a grow tent are essential, particularly during the growing stage. 

To put it in simple words, uncovering your plants to relatively high humidity helps your plants with retaining the water they need in order to sustain themselves. Plants take up water through the roots. However, they could also get more water through their leaves and stem. 

As explained before, plants suck up water through water vapour presenting the air through the minuscule opening on the leaf surface called stomata. Your plants might not have an ample amount of water for their proper growth and nourishment if there is less humidity.

A Few Safety Measures You Must Follow While Raising Humidity in Grow Tent:

  • While removing fluorescent lights, check if your plants are getting sufficient light. Or else, this would be an awful trade-off.
  • While consolidating large plants with little ones, ensure that none of your plants is in the blooming stage. You might end up influencing your grow plant fertilization.
  • While hanging wet towels, double-check that you are not covering up the light sources.
  • While building up your own propagation set up, be extra cautious with the electrical work. Dealing with water and electricity at the same time is quite risky.
  • When using new soil as the base, use gloves. Also, after using the new soil, is cautious while entering your grow tent. One slip, and you may tumble down.
  • While using water-based methods, monitor how much water you are using. It would be best if you did not overuse it.
  • Keep electrical supply points and water sources away from one another. To be more specific, do your wiring correctly.

Raising the humidity of a grow tent is a difficult job. In any case, it will feel more arduous if you end up making mistakes or do not take care of your safety.

Well, with this, our article comes to an end. By now, we are hoping that you have mastered the art of increasing the humidity levels in your grow tent.

Leave a Comment