Controlling Humidity In Grow Tent (How To Lower Humidity In A Grow Tent)

One of the aspects of growing cannabis in a grow tent is learning how to control the humidity. You may think this is something you may not be able to deal with yet you can with a few tips and perhaps several pieces of equipment.

If you want to maximize your yield and prevent mildew then it is crucial to keep the humidity just right. Fluctuations may occur so it is fair to look out for the humidity levels night and day as it can change and that can harm your cannabis plants. 

Controlling Humidity In Grow Tent (How To Lower Humidity In A Grow Tent)

In this guide, we will detail controlling the humidity in a grow tent. This will include how to lower the humidity, what the ideal humidity is, and how to keep the ideal humidity level.

We will also look at whether wild mold grows at 55 relative humidity, and if 50 or 60% is ok in a grow tent. 

What Is The Ideal Humidity For A Grow Tent? 

The ideal humidity for a grow tent should be between 50 and 55% relative humidity. At this level, you can actively prevent the growth of powdery mildew as the spores cannot survive at a humidity level of that range.

A relative humidity between 50 and 55% should also prevent the growth of several other fungal plant diseases. If you can protect your cannabis plant from such diseases and mildew that it can keep your harvest intact in the long-run.

You may want to look at increasing the relative humidity to a level between 65 and 70% as the cannabis plant grows, particularly in the veg phase.

However, it is recommended that fluctuations of humidity over around 10% are not advisable. If you are to raise the level then do it gradually. 

How To Keep The Ideal Humidity Level

Once you have hit the ideal humidity level, you should look to keep it to look after your cannabis plant and ensure its growth. 

  • Pay close attention to the readings from your hygrometer and note down the daily high and low levels. 
  • You may want multiple hydrometers to check the humidity level in various parts of your grow tent. 
  • Try not to water your cannabis plants at night as this can cause the humidity level to spike. Water them in the morning when they are awake and need a drink.
  • Check if the ventilation is good enough in your grow tent and invest in an air conditioning unit if you feel it needs to be improved. A couple of clip-on fans may be sufficient though you may want to try an intake fan or an exhaust.
  • It may be helpful to open the doors to your grow tent but not during dark time when they are supposed to be flowering. It may be common advice to keep the doors closed on your grow tent but feel free to open them when you see fit.

Does Wild Mold Grow At 55 Humidity? 

Without any cold-condensing surfaces and if a relative humidity under 60% is maintained in your grow tent then you can expect that wild mold will struggle to grow.

That’s due to that lack of water for the mold to grow. Maintain that level of relative humidity as, should it grow to over 70%, then mold will undoubtedly grow if the humidity is left for an extended duration. 

Is 50 Or 60% Humidity OK In A Grow Tent?

As we said earlier, a relative humidity level between 65 and 70% is at the upper reaches of what you would expect for the veg phase.

However, the humidity goal should remain at around 50 to 55% to prevent the growth of fungal plant disease and powdery mildew.

It may depend on what stage the cannabis plant is at that determines whether you go for a humidity level closer to 50% or 60%. 

Should you be rooting clones, then you can expect the relative humidity to creep from 50 to 60%, it may even go beyond 70%.

At those levels, you may be creating an environment and a humidity that is especially conducive to that destructive powdery mildew.

Keep an eye on your plants yet once the spores have infected the surface it can only be a matter of days before the mildew globs take hold and by then it may be too late. 

Final Thoughts

The humidity level in your grow tent is a crucial factor in the growth and development of your cannabis plants.

Make sure that you can accurately gauge the humidity levels and put the relevant measures in place to keep it steady once you hit that ideal humidity level.

If you need it to be higher then close the doors or invest in a fan if you need to lower it. Whatever you need to do, ensure that you keep fungal plant diseases and powdery mildew at bay if you want to look after your cannabis plant.

Frequently Asked Questions

What Is The Optimum Humidity Level For Curing Cannabis?

The optimum humidity level for curing cannabis is between 60 and 65% and you should know how to reach that in your grow tent. However, before you can expect the curing to start, your cannabis plants will need to dry out first.

This typically lasts for a few days as you look to lower the water content from around 75% down to between 10 and 15%. 

What Is The Ideal Humidity Level For Flowering Cannabis?

If you can get the humidity level in your grow tent to between 40 and 60% then that should be ideal for flowering cannabis.

During flower, you can look at lowering the humidity to prevent mildew and mold. Look to drop the temperature to look out for the lower relative humidity too. 

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