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Ideal Grow Room Humidity for Cannabis

Seedling Humidity and Temperature

  • Humidity: 65-80%
  • Temperature: 70–85°F lights on / 65–80°F lights off

cannabis seedling germination clone ideal climate

At this stage, your plants have not yet established their root systems. Creating a high-humidity environment in your nursery or clone room will reduce transpiration through the leaves and take the pressure off the immature root systems, allowing the root system to catch up before ramping up VPD and transpiration.

Many growers opt to start clones and seedlings in mother or veg rooms, in which case they may use plastic humidity domes to help retain moisture (and in some cases heat), allowing them to share space with more mature plants without similar environmental constraints. However, if you use these domes, ensure they have proper ventilation to prevent building up too much moisture and to ensure exchange of CO2.


Veg Room Humidity and Temperature

  • Humidity: 55-70%, gradually lower humidity in 5% increments periodically until you reach the humidity that facilitates transplant to flower (do not go lower than 40%)
  • Temperature: 70-85°F lights on / 60-75°F lights off

best temperature and humidity for cannabis in veg

Once your plants have reached the vegetative stage, you can begin gradually stepping down the humidity. This will give you time to prepare the plants for flower. Until then, they will further develop their root systems and complete the majority of their leafy growth and stem elongation.

Cannabis veg humidity should start between 55% to 70%, and incrementally decrease to the humidity level you will use in flower. Do not lower the veg room humidity below 40%.

Flower Room Humidity and Temperature

  • Humidity: 40–60%
  • Temperature: 65-84°F lights on / 60-75°F lights off

best temperature and humidity for cannabis in flower

The ideal cannabis flowering humidity is between 40% to 60%. During flower, lowering your relative humidity level can help prevent mold and mildew from forming. To accommodate the lower RH, cooler temperatures will also help you maintain your ideal VPD. Avoid high temperatures above 84°F, especially during the second half of flower. High temperatures at low humidities can quickly dry your plants out and cause them stress, which is bad for your yield.

Drying and Curing Humidity and Temperature

  • Humidity: 45-60%
  • Temperature: 60-72°F

ideal environment for drying and curing cannabis

Your grow room HVAC control needs do not end postharvest. Your drying room should maintain a humidity around 45% to 60%, and you should keep temperatures down. Your buds will continue to release moisture as they gradually dry out, but dropping your humidity too much could cause them to dry prematurely which will ruin their taste and quality. Also, temperatures above 80°F can damage terpenes or cause rapid drying as well, so beware of high temps.

Post time: Jun-17-2023