From seed to storage, humidity is one of the most important factors when it comes to nurturing root systems and growing cannabis that is designed to persevere.
Perfecting your grow room humidity range is essential for plants to stay healthy and free of unwanted bacteria and mold. On the other end of the growth cycle, the right humidity levels in the curing and storage stages help your buds remain flavorful and potent.
Cannabis flower undoubtedly thrives in good humidity; however, there is such a thing as too much or too little moisture content, and both ends of the spectrum can become a dangerous environment for your cannabis plant to live in.
To ensure you know how to find the temperature and humidity sweet spot for growing, curing, and storage success, keep reading.
Ambient Vs. Relative Humidity
Ambient humidity refers to the environment outside of your cannabis container or humidity bags. In cannsbis, this is your grow room or the room in which you’re curing or storing flower. Rooms with an air conditioner running typically have a moisture level of around 20-30 percent. On the other hand, relative humidity (RH) refers to what’s going on inside your cannabis container, and the ratio of water in the air to the temperature of the room.
Warm air is generally better at holding water than cold is, which is why ambient humidity levels in two cities can be the same even if their temperatures are 20 degrees apart. But because the warmer air water retention in the hotter city holds more water vapor, its RH level will be higher.
The best humidity for cannabis storage sits at around 59-63 percent RH, while a drying room stays between 50-60 percent. The RH for curing cannabis should be about 60-65 percent.
Active Vs. Passive Humidity Control
When figuring out the ideal humidity for cannabis, the first thing you’ll want to take a look at is your bag humidor of choice, and how it responds to the atmospheric humidity. There are two types of humidity control you’ll need to think about: active and passive.
Active humidity control refers to any material that actively contributes to the environment and/or the creation of the environment. For example, the Integra Boost, Boveda Pack, or Boveda Humidor Bags utilize 2 way humidity control that has a direct influence on the environment’s level of humidity or RH.
Passive humidity control is a material that doesn’t add anything to the environment—like Grove Bags’ Terplocs. Instead, moisture in and around the cannabis nugs you place in the bag will evaporate and release oxygen and water vapor. The bag will allow a certain amount of moisture and oxygen to exit the packaging, ensuring that whatever is left is an essentially perfect environment for cannabis.
What’s the best humidity to store cannabis?
As we mentioned earlier, the best humidity for weed sits at around 59-63 percent RH, but the range can be anywhere from 55-65, depending on your desired outcome.
It’s so important to have a way to measure your humidity levels while storing your product, as things like temperature and environment can have drastic effects on the humidity, and in turn, the quality of your cannabis.
It’s simple enough to dehumidify bags if your levels are too high, or vice versa, but without the ability to access percentage levels in the first place, you’ll be wading in the dark wondering if you need passive or 2-way humidity control.
How does humidity affect curing, drying, and storing cannabis?
When it comes to curing weed, RH levels should stay between 60-65 percent for the best possible results. However, the bigger concern at this stage isn’t humidity: it’s temperature and lighting.
Too-high temperatures put your cured buds at risk of decarboxylating, which would seriously deteriorate your product’s potency by the time it reaches market. For that same reason, it’s important to store your bud in a darker environment rather than under the bright lights.
If you’re in the process of drying the buds, make sure your humidity is between 50-60 percent. You will not want the air heavy with moisture while the flower’s on the drying rack, but you also don’t want your flower to shrivel up if the environment’s too dry.
How to raise the humidity
As long as you know how to identify humidity levels and understand what works and what doesn’t, raising the humidity is a pretty straightforward process.
The easiest way to raise humidity when drying and curing cannabis is to mist your plants with a spray bottle of water. The spray bottle method is inexpensive, efftive, and easy to do.
Other options include keeping the soil’s surface moist but not wet, hanging wet towels or cloths in the grow room. If you have the budget, you might want to consider investing in a large humidifier.
How to lower the humidity
Lower your grow room humidity by turning up the air flow fans. You can also water your plants immediately after switching your lights on, as the room will be cooler and your plants will absorb the water quickly, leaving less room for increased humidity.
For those with higher budgets, you can invest in a dehumidifier and opt for a larger one if you have a particularly grand grow room.
Frequently Asked Cannabis Humidity Questions
What’s the best humidity for cannabis seedlings and clones?
When cannabis is starting its journey, it loves humidity. Most growers aim for a relative humidity of 60-80% when the plants are still in the seedling or clone phase.
What’s the best humidity for the vegetative phase?
At this stage, the cannabis plants will require a relative humidity of 50-70%. Maintaining a warm microclimate at this point is critical as you prep your plants for the next phase of flowering.
What’s the best humidity for the flowering phase
This is the phase that most cannabis growers look forward to because they finally get to appreciate their weeks of hard work. The flowering phase requires a humidity of 40-60%, the lower the better. High humidity will increase the chances of bud rot invading the canopy. However, the transition from high to low humidity should be gradual to avoid stressing out the plants. Think of the “Guru of Ganja,” Ed Rosenthal’s advice for cannabis cultivation and go “low and slow.”
What’s the best humidity for drying cannabis?
A drying room’s ideal relative humidity (RH) will sit at around 50-60 percent.
What’s the best humidity for curing and storage?
For storing and curing, set the humidity range to 60-65 percent.