Achieving Ideal Temperature + Humidity | ‘Grow Girl’

The humidity and temperature of your home grow can effect the growth and final yield of your harvest. Just like people, cannabis feels most comfortable when the humidity and temperature levels aren’t too high or too low.

In all stages of cannabis growth, your plants will have a constant need to intake water, and the amount of water they need fluctuates with the humidity in your room.

What is Humidity? Humidity measures how much water is currently being ‘held’ in the air. There are three ways to measure humidity, “absolute”, “specific”, and “relative” humidity. In our case, we will be referring to relative humidity (RH).

Relative humidity (RH) measures how much water is in the air compared to the maximum amount of water than can be held in the air at that temperature.

The basic tools that you will need to measure and control the temperature and humidity of your grown room are:

  • Temperature & Humidity gauge
  • 8,000 btu AC unit
  • 70 pint per day dehumidifier

Along with a quick reference guide to how humidity effects the cannabis plant throughout it’s life cycle. We’ve included Jairia’s favorite grow charts, to help you grow at home and on a budget.

Submit your home grow questions for Jairia using #AskJairia.


Optimal Humidity: 70-85% RH

Approximate Temperature(s): 80 -84º

Clones need time to develop a root system to intake water. Young clones are dependent on getting water through their leaves from the air and this is only possible with high humidity.

Vegetative Period

Optimal Humidity: 70-85% RH

Approximate Temperature(s): 77 -84º

In the vegetative period young cannabis plants grow a lot of leaf foliage. The idea is to create a comfortably warm environment that mimics springtime.

Early Flowering

Optimal Humidity: 60-75% RH

Approximate Temperature(s):

Once your cannabis plants enter the early flowering stage, they have created a large enough root system to fulfill their water needs. Once your grow begins flowering, you will want to dramatically reduce the RH in your grow. This is to prevent your crop from mildew and mold.

Late Flowering

Optimal Humidity:

Approximate Temperature(s):


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Executive Producer | Vat Tann

Creative Producer | Elliott Vecchia

Associate Producer | Brett Miller

Director | Sean Willis

Gaffer | Jesse Lee

Grip | Chris Hartsell

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Assistant Camera | Dennis Noack

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Production Assistant | Jordan Ferrin

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