DIY Extraction

Tips for Keeping Your Hash Mold-Free

Written by Petar Petrov

Mold is one of the most devastating plights in the cannabis world, with both producers and consumers alike looking to avoid it and its physical and financial damages. But mold can be as harmful as it can be tricky.

Mold can enter the picture long before the consumption phase. Warmth, humidity, and stale air create an environment mold thrives in, regardless of what stage of its life cycle cannabis is in.

With that in mind, here are several ways to prevent mold from creeping into your hash.

Prevent Mold at the Growing Phase

Installing fans over your plants that gently move the air around and create a light breeze can be enough to shut mold down. So can sufficient space between plants. Humidity sensors may save you lots of hassle and losses down the line and more than pay for themselves.

Keeping your growing tools clean and sterile is another fundamental step toward mold-free cannabis, especially before defoliation and pruning.

Furthermore, be careful not to overwater your plants, as the extra water won’t just disappear into thin air, but mix into the air and make it humid.

Proper Curing and Pressing

Making hash from even slightly wet cannabis flower can result in moldy hash, assuming it results in hash at all. Careful curing of your material is crucial for preventing mold in your hash. Allow extra time to ensure that your hash is well-dried before putting into a storage container. Frenchy Cannoli ideally recommends drying in a room with approximately 35% humidity set to 55°F or investing in a freeze dryer, since it “can guarantee a perfect drying process in approximately 48 hours.”

Proper Storage

Air is the doorway through which mold makes its way to your hash and cannabis, as it can bring humidity and warmth into your storage “facility.” Keeping hash airtight is the name of the game, whether it’s an amber glass jar, or some other container. Even after oxygen has been depleted in an airtight container, anaerobic bacteria can still thrive, and Ed Rosenthal reports that this type of bacteria can be identified as producing “an acrid ammonia odor.”

As mentioned above, warmth is to be avoided, so keeping cured hash cool in the refrigerator can help ward off mold.

Types of Mold and Battling Them Post-Factum

Botrytis is a type of grey mold that can be eliminated by pruning.

Powdery mildew, which looks the way it sounds, can be wiped down with a wet paper towel.

Mold in soil poses a bigger challenge, as it targets cannabis at its foundation, potentially causing sweeping losses. Because of its holistic attack, it’s crucial that you prevent it rather than fight it post-factum. You can do this by inoculating with bacteria like Bacillus subtilis, which has antifungal properties [1], or Trichoderma (e.g. T-22).

These tricks may sound simple, and they are for the most part, but they’re also effective and can go a long way in creating an unwelcoming environment for mold.

Image Credits: Wikicommons


  1. Hashem A, Tabassum B, Fathi Abd Allah E. Bacillus subtilis: A plant-growth promoting rhizobacterium that also impacts biotic stress. Saudi J Biol Sci. 2019;26(6):1291-1297. [journal impact factor = 2.802; times cited = 20]

About the author

Petar Petrov

Petar is a freelance writer and copywriter, covering culture, art, society, and anything in-between that makes for a nice story. And as it so happens, cannabis is a great element to add to each of those conversations.