Guide to Ideal Temperature and Humidity for Drying Weed

It’s important to dry cannabis flowers in an environment with the right temperature and humidity levels so that your buds don’t go moldy or become overly dry and brittle. You also don’t want them to dry too fast or too slowly, or unevenly, as these factors can lead to the exact same problems.

To optimize your drying and curing process, you’ll need to create a controlled environment with an air conditioner, fans, drying racks, and little-to-no light exposure. Once your drying room is set up, using strategically placed temperature and humidity gauges, along with periodic in-person checks, will help to ensure consistent results.

Optimal Temperature and Humidity Levels for Drying Cannabis

The ideal parameters for drying cannabis flowers, according to a systematic review published in Molecules in 2022, is a temperature of 18 to 21 °C (approximately 65 to 70 °F) and 50 to 55% relative humidity. Once the moisture content of the buds reaches 8 to 10%, you can jar them for curing.

Depending on the initial moisture content of your buds, whether you opt for wet trimming or dry trimming, and the exact temperature and humidity of your drying room, the drying process could take anywhere from five days to around two weeks or more.

How to Set Up a Drying Room to Ensure the Optimal Conditions

We’ve established the ideal temperature and humidity levels for drying cannabis. Now, how do you achieve these parameters in practice? Nowadays, commercial growers often use automated environmental control systems to create the exact humidity and temperature conditions needed for drying cannabis. If you’re setting up a drying room manually, you might need:

  • An air conditioner. Air conditioners are used to keep the drying room at the correct temperature.
  • Fans. Fans are used to direct airflow. In a drying room, you want both vertical and horizontal airflow to make sure your cannabis plants dry evenly. Avoid blowing air directly at the cannabis plants, however, because this can cause them to become overly dry.
  • Drying racks. Drying racks come in all types of simple-to-elaborate-style set ups as they help your plant material to dry evenly and maximize the number of plants that you can dry in a single drying room. As an alternative, some people use a hanging method with coat hangers or mesh bags that are suspended from washing-line-style ropes.
  • A humidifier. In very dry climates, you might need a humidifier to raise the relative humidity of the room to the ideal range for drying cannabis.
  • A dehumidifier. A dehumidifier removes the excess moisture from the drying room—both the ambient moisture and the moisture content of your wet buds that’s evaporating into the air. Your dehumidifier should be capable of handling up to 50% of your plant material’s initial moisture content in a short amount of time, as this amount of moisture content typically evaporates in the first 24 to 48 hours.
  • Temperature and humidity gauges. Place these gauges in a few different places around the drying room, preferably near your cannabis plants. There are also many digital solutions available to automate sensor readings and control a variety of devices simultaneously.
  • Low-intensity lights. A drying room should be dark to prevent terpene and cannabinoid degradation. However, you’ll need a few low-intensity lights (preferably green) for checking the buds and taking readings from the temperature and humidity gauges. These lights should only be turned on when you enter the room and turned off as soon as you leave.
  • Air filters. Air filters can be used to prevent contamination from the air outside the drying room coming in and also to prevent cannabis odors from leaving the room.
  • Positive pressure. Some growers add positive pressure to their drying room to prevent contaminants from entering the room when they check on their buds.

Other Things to Keep in Mind for an Optimal Drying and Curing Process

We’ve covered the basics of creating the ideal controlled drying environment. However, there are a few additional points to keep in mind when establishing your standard operating procedures (SOPs) for drying cannabis.

Keep the Temperature and Humidity Consistent

There’s a five-point range for the temperature and humidity levels when drying cannabis. However, that doesn’t mean you can let your drying room fluctuate freely between the minimum and maximum values.

For consistent drying, you should establish in-house temperature and humidity levels and make sure everyone in the grow operation follows these guidelines. Ideally, the temperature shouldn’t vary more than around 2 °F (1 °C) and the humidity levels shouldn’t vary more than 3% throughout the drying process. The same temperature consistency considerations can be applied throughout all post harvest practices from the trimming stages through to storage after packaging.

Wet Trimming vs Dry Trimming

The point at which you trim your buds (before or after drying) will also affect the drying process. You should always remove the excess fan leaves before drying because they’ll prevent your buds from drying properly, while also having the benefit of preventing molds and mildews from forming and going airborne. However, it’s ok to trim off the sugar leaves before you dry your cannabis flowers (wet trimming) or trim them off after the cannabis buds are dry (dry trimming).

Consider wet trimming if:

  • You want to employ lyophilization techniques (and or intend to Cryo-Trim® while wet with The Original Resinator).
  • You have the adequate manpower, time between turnovers, and appropriate dry rack system in place to air dry your cannabis buds.
  • You live in a very humid climate (as you’ll need to maximize air circulation to the buds).
  • You have fresh-frozen cannabis and want to make live bubble hash with the trim.

Consider dry trimming if:

  • You live in a very dry climate, as the sugar leaves will help to prevent the buds from drying out too quickly.
  • You have an adequate dry-and-cure space with proper environmental controls.
  • You prefer hand trimming.
  • Your operation can not support a commercial or scientific freeze dryer.

Whether you opt for wet trimming or dry trimming, you’ll need to trim your buds before jarring them for the curing process. Experiment with both methods and see which one works best for you.

Expedite the Drying Process with a Freeze Dryer

Growers have been drying and curing cannabis in drying rooms for as long as there’s been a cannabis industry. However, newer techniques like freeze drying allow you to dry weed quickly without sacrificing quality. With a commercial freeze dryer, you can dry cannabis flowers in as little as a day (compared to a week or two for air drying), while preserving terpenes and cannabinoids, preventing mold growth, saving on labor costs, and making space for the next batch of buds.

If you trim your buds with CO2 at low temperatures with an Original Resinator, you can freeze dry the trimmed buds and cure them in as little as a few hours or overnight for a total freeze drying Crop-to-Cure® time of 24 hours. By trimming the buds prior to freeze drying, you will have up to 25% more space in the freeze dryer and can streamline your workflow for maximum efficiency.

Risks of Improper Drying Conditions

With the proper drying conditions, you can produce cannabis buds that are flavorful, aromatic, and potent. However, with substandard drying conditions, your buds can end up moldy and unsafe to consume, lacking in terp profile, or overly dry and harsh to smoke.

In a competitive market with increasing lab testing requirements, it’s essential to make sure that your buds are spot-on every time in terms of moisture content and biological safety. After you invest so much time and effort in perfecting your growing process, it makes sense to ensure that your dried and cured cannabis buds are as fresh, potent, and flavorful at the point of sale as they were at the time of harvest.

Optimize Your Drying Process for Maximum Returns

Drying removes excess moisture from cannabis buds so that they can be cured and consumed without any risk of mold growth or the unpleasant taste of wet weed. Getting the temperature and humidity levels of your drying environment right is essential for helping the buds dry properly to ensure the most potent and flavorful results.

For rapid drying without any drop in quality, freeze drying is the best solution. A freeze dryer can dry your buds in as little as a day for maximum potency and terpene retention and faster turnaround times. When coupled with cold-trimming using The Original Resinator, you can cut your Crop-to-Cure® times down to 24 hours with award-winning results.

TJ Arnovick

Cannabis extraction expert and founder.