Mold afflicts cannabis to such an incredible degree that an entire subspecies of the plant had to evolve with a different anatomy to prevent mold growth. How ubiquitous is mold in cannabis? It’s roughly as common as under-cured pot, which means very common. Check out this simple trick to stop mold growth in its tracks for live buds, curing and storage.

Mold spores exist everywhere; even the highly purified of outer-space satellite factories still contains traces of dust and mold. If a growroom has filters in place in its intake ducts, the interior air should, in principle, contain less mold spores than outside air. Despite the even minor presence of spores, mold may still proliferate if conditions are too humid. In the proper humidity levels, live plants exude natural products that keep mold growth at bay in its own living tissue, but once the plant dies during harvest, the entire crop is at risk of mold colonization.

Humidity control during curing is of utmost importance. The grower must assure that the relative humidity of the air remains around 50-60 percent, a good range to prevent mold growth on the one hand, but not so low that the buds dry out so fast they attain an unfavorable consistency. Even with humidity levels in the air in the proper range, as long as the buds retain above 12.5 percent water by mass, they will still be at risk of mold formation. These humid flowers generate local pockets of humid air within the anatomy of the bud, which is why constant air circulation is a must.

So you got your hygrometer, dehumidifier and circulating fans, and you think everything is perfect, but one fateful day you take peak in the calyxes of your beautiful buds and you see the white spindly hairs of hyphae bud-rot. What could have gone wrong? Even under perfect atmospheric conditions, bud-rot can still proliferate because cannabis buds simply make the perfect environment for mold. This problem requires a little help from our good friend technology.

Ultraviolet light has been implicated as a potential method for increasing THC potency in cannabis. Little did they know, growers that supplement their gardens with UV-light during flowering are also getting the added benefit of mold prevention. In the same way short-wavelength, UV-C light is harmful to human skin because it penetrates cell walls, breaks up DNA and causes malfunctions in cell reproduction that can lead to cancer, UV-C light also breaks up the DNA of single-cell mold spores and kills them.

Placing a deep-UV LED lamp in the curing and storage room will help prevent mold proliferation by slowly, but consistently killing spores circulating in the air. Try and place the lamp so the beam does not shine directly on the drying, or dry, flowers. The constant flux of UV light on the flowers may degrade its content of aromatic terpenes.

Mold-rated UV-C lights are great mold protection in other parts of the garden as well. Placing UV-C lights in front of HEPA filters in air intakes assures that the mold spores it captures do not turn the filter itself into a breeding ground. In addition, shine UV-C light on the cooling tubes and drip pans of your air-conditioning unit to assure that mold does not proliferate in these high-risk areas.

Use precaution when handling UV lamps. Do not let the light shine on any part of your body; it may present a hazard to your skin. Additionally, UV lights present a danger to your respiratory system due to the formation of ozone. Ultraviolet light reacts with molecular oxygen (O2) to form ozone (O3) in small quantities. Ensure that any area under UV irradiation has an adequate airflow. Regulations state that workplace or residential atmospheres must not exceed a level of 50 parts per billion of ozone. Any grow operation that wishes to withstand OSHA regulations must measure ozone concentrations in UV-irradiated areas to assure they do not exceed 50 ppb, as higher concentrations present a health hazard. Ozone tests can be expensive, so try and use your nose first; if you are able to smell the ozone (a smell reminiscent of laser printers in use), you definitely need more ventilation.

They key is growing cannabis, not mold. The spindly buds of many Sativa strains may be more tolerant to mold, but don’t push it. When it comes to growing dense Indica buds, more precaution and care must be taken, in part due to the fact that the dense make it harder to spot mold at the first glance. As a consumer, if you receive some cannabis you suspect to be moldy, the first step you may want to take is drying the buds to an adequate low level of moisture, and some UV irradiation with a cheap lamp won’t hurt either. Even it means loosing some value in the water-weight, its better than giving yourself and your friends bronchitis for a week.

Photo Credit Stephanie Curtis