Temperature and Humidity Requirements for Autoflowering Cannabis Plants

Greetings, budding botanists, and welcome to another green-thumb guide from your favorite expert grower at the Dutch Seeds Shop. Today, we’re turning up the heat and cranking up the moisture, getting down to the nitty-gritty of temperature and RH control for our beloved autoflowering plants. So grab a cup of joe, sit back, and let’s dive…

Temperature and Humidity Requirements for Autoflowering Cannabis Plants

Understanding the Importance of Temperature and Humidity

Managing temperature and relative humidity in your grow room is like DJing for your cannabis plants – the right balance keeps the party going, while missteps can lead to a disaster quicker than you can say “bud rot.”

Imagine your cannabis plants donning tiny fur coats when it’s chilly and wielding itty-bitty umbrellas when it’s too damp. 

Understanding the Importance of Temperature and Humidity

The best humidity and temperature conditions stimulate growth, affect yield, and protect your precious crop from diseases and pests.

It’s like organizing a botanical spa retreat for your greens – the better the ambiance, the better the rewards.

Optimal Temperature Ranges

Let’s set our sights on the thermometer first. Different stages of your plant’s life require different comfort zones.

Think of it like this: you wouldn’t wear a sweater in the heat of summer, would you?

  • Seedling Stage: Like baby bears, cannabis seedlings prefer the “just right” range of 20-25°C (68-77°F). These baby steps into growth need just the right amount of warmth!
  • Vegetative Stage: As your little green warriors grow, they can withstand more heat, with a sweet spot between 22-28°C (71-82°F).
  • Flowering Stage: It’s a bit chillier here, ideally between 20-26°C (68-78°F). It’s like setting the mood for your plants to start their magical, fragrant blossoming.

Remember, the range might be a bit wider for autoflowers due to their robust cannabis ruderalis plants genes, but fluctuations beyond these ranges could leave your plants singing the blues.

Ideal Humidity Levels

Now, on to the optimal humidity ratio in different growth stages.

Humidity basically is the amount of water vapor that is in the air.

Absolute humidity is the maximum amount of water vapor that the air can hold at a specific temperature.

Ideal Humidity Levels

Relative humidity is measured in percentage from the absolute humidity value. The best way to measure humidity is by using a hygrometer.    

If the temperature was our DJ, humidity is the dancefloor – too slick, and your plants might fall into the clutches of mold and diseases; too dry, and they might end up thirstier than a camel in a desert.

  • Seedling Stage: Increase humidity range to 65-70%, ensuring your seedlings don’t feel like they’ve stepped into a desert.
  • Vegetative Stage: Gradually turn the knob down to 40-70%, and it should not surpass the 90% mark or else the plant will suffer and will not be able to evaporate the absorbed water through the leafage, decreasing humidity levels by about 5% each week is recommended.
  • Flowering Stage: Here, the range is 40-50% at the start and 30-40% near the harvest. It’s like setting the stage for the grand finale. However, you probably shouldn’t use the hand mister in the flowering phase of the plant’s life because if the water gets on the dense buds mold or other infections can start to grow.  

Remember novice growers, like that one time you overwatered your plants (we’ve all been there), too much of a good thing can backfire – high humidity during flowering can welcome unwanted guests like bud rot and mold.

Temperature and Humidity Control Techniques

So, how do we achieve these perfect conditions? Simple, we bring in some gadgets and gizmos!

  • Ventilation: Keeps the air fresh and the party pumping.
  • Fans: Autos best friend in the heat of summer. 
  • Heaters: For those chilly nights when your plants need a warm hug.
  • Air Conditioners: Beating the heat like a cool ocean breeze. Autoflower typically thrive in a slightly cooler environment than photoperiod strains.    
  • Humidifiers and Dehumidifiers: The dial on your auto-flowering cannabis dancefloor. Using a humidifier is an easier way to correct optimal humidity indoors but is considered a very drastic measure. High humidity can turn a small area like a grow room into a humidity dome. This area will be too rich with moisture and will be severely damaging to your growing autoflowering cannabis plants.

Monitoring and Measurement

You’re not going to eyeball your autoflower temperature and humidity, are you?

“Ahh feels like 22°C to me!” won’t quite cut it. 

Invest in a quality thermometer and hygrometer – like the glasses that let you see the invisible world of your autoflower comfort.

Regular monitoring of these levels can be the difference between “my plant is rocking” and “Why is my plant rocking?!”

Trust me, I’ve seen more plants go to heaven due to humidity and temp negligence than I’d like to remember.

Tips for Managing Temperature and Humidity

Now, before we part ways, here are a few more nuggets of wisdom from yours truly:

  • Consistency is Key: Like a grumpy old man, your plants hate sudden changes. Slow and steady wins the race!
  • Beware of Extremes: High heat and low humidity – sounds like a disaster recipe, doesn’t it? It can lead to water loss, stress, and, at worst, your plant playing dead. if you have additional issues related to increasing levels, a humidifier may be required
  • Micro-Manage: Make tiny adjustments if you notice your plant going “Why me?” on you. Small changes can have significant impacts!
  • Know When to Say When: Avoid the temptation of overdoing things. Remember, even if you’re pumping iron at the gym, your body needs rest. The same goes for your plants!


Just as a gourmet chef understands the delicate balance of ingredients, a master cannabis cultivator knows the nuances of temperature and RH control.

It’s the secret recipe that makes the difference between “meh” and “magic!”


So, maintain the ideal conditions, give your plants the VIP treatment they deserve, and you’re on your way to a bumper harvest.

Stay green, my friends, and happy growing!


What is the best environment for Autoflowers?

Autoflowering strains thrive in well-ventilated grow rooms, 23-28°C (73-82°F) day temperatures, 15°C (59°F) minimum night temperature, and 40-60% humidity.

What temperature do Autoflowers like?

Autoflowers like 23-28°C (73-82°F) daytime temperatures.

How do you know if your Autoflower is heat stress?

Heat stress in autoflower shows as leaf curling, yellowing, or browning and slowed or halted growth.

What temperature and humidity should a grow tent be?

A grow tent should be 23-28°C (73-82°F) with 65-70% humidity for seedlings, 40-50% in early flowering, and 30-40% in late flowering.

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