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Odor Control Tips for Your Indoor Cannabis Grow Room

December 14, 2016

As much fun as starting your indoor cannabis garden can be, having a home perpetually filled with the smell of fresh flowers can be a serious inconvenience, if not to you than perhaps your neighbors. Although smells from a micro-sized, one plant closet garden is much easier to manage than a larger grow tent holding several flowering plants, either scenario can produce pesky odors that will permeate an entire home if left unattended.

Fortunately, there are a range of techniques that can be implemented to mitigate this odiferous opportunity which can be implemented in any sized indoor grow. If used in combination with one another, many of these techniques are capable of completely removing all odors in a cannabis grown room, leaving you to propagate worry-free.

Check Your Temperature and Humidity Levels

A finger pressing a digital thermostat

The first step in proper odor management is to make sure that your grow space’s temperature and relative humidity are under control. High temperature and humidity will perpetuate any odor issues that your garden may encounter, though this will most affect your garden in the bloom phase.

Plants that are in their vegetative phase maintain a very low odor as the plants have not yet begun to produce terpenes, the molecules responsible for a cannabis plant’s aromatic properties. As cannabis transitions to its bloom phase and begins to produce flowering nodes, trichomes will develop. Being the molecule factories that they are, trichomes begin to produce these aromatic compounds in abundance.

How to Increase Production of Ripe Trichomes on Cannabis

As your plants continue to grow and transition, temperature and humidity become increasingly vital to manage in order to keep odors under control. Some ways to immediately tackle these issues include outfitting your grow space with dehumidifiers and air conditioners. Although these options will greatly benefit a closed space, moving heat and humidity out of a room may be the better place to start.

Make Sure Air is Circulating Through Your Garden

Spinning Electric Fan Blades

Proper air circulation is at the center of maintaining temperature and humidity control. All grow lights produce heat in varying quantities. Smaller grow systems utilizing cooler lights such as compact fluorescents or LEDs may have an easier time suppressing heat than hotter systems like high intensity discharge (HIDs) or ceramic metal halides, but both will fry your garden with dangerously high temperatures if there isn’t adequate ventilation and circulation.

Ideally, air needs to move through a garden every few minutes during vegetative phases and every minute during bloom phases. Not only does air circulation help keep temperatures and odors low, it will recycle used CO2 out of your grow space. The easiest solution to air circulation is to outfit your garden with fans. Standing fans, oscillating fans, as well as ducted intake and exhaust fans will all do wonders in and of themselves, but when combined, they can move air through your garden in a matter of seconds, taking odors out with them.

Organic vs. Chemical Cannabis Fertilizers for Your Grow

When you’re looking to outfit your garden for the right sized fan, look for a CFM rating. This will give you an indicator as to how much cubic feet your fan is capable of moving through a space in a minute (you’ll need a cubic foot/meter measurement of your grow space for this).

Odor Absorbing Gels May Help

Smelling the plant

Odor becomes much more difficult to manage in the final six weeks of a cannabis plant’s lifecycle. This is the stage where trichomes are producing their highest concentration of terpenes, and your garden is certainly going to try to show them off to you (and perhaps to your neighbors). Air circulation and ventilation aside, there comes a time when all of the air in your living space will contain traces of your garden’s fresh floral smell.

At this point, you may want to consider more rigorous odor management practices such as odor absorbing gels. These products work by attaching to odors and replacing them with other, more appealing scents. Keep in mind that odor gels do not eliminate odors, but simply mask them. Odor eliminating sprays help a bunch as well, but they operate under the same principle, not actually removing odors, but simply making them more pleasant.

Try Activated Carbon Filters

Closeup view on air filter. Filtration concept.

If you want to destroy 90% of the odors in your garden on contact, you’ll want an activated carbon filter. Also known as “carbon scrubbers” for their ability to literally scrub contaminants out of the air, these devices employ activated and highly ionized carbon to attract particulates from the air. Dust, hair, mold spores, and volatile organic compounds responsible for carrying odors are all trapped either in a pre-filter or by the ionized carbon molecules inside of the filter’s main cylinder.

Filters in a flowering garden can serve one of two purposes. With CO2 supplemented air or in rooms very high in CO2, filters can be placed on the floor to recycle scrubbed air back into your space. However, most rooms utilize carbon filters with an exhaust, a great way to not only redistribute heat, but stale, depleted air as well.

How to tell if a cannabis plant needs watering

Carbon filters come in different shapes and sizes and can be complemented by the addition of a duct fan. This will either serve to circulate contaminated air though your filter or to exhaust clean air out from your filter with the assistance of some ducting. Not all carbon filters are created equal, so be sure to purchase a reputable model. Filters come in various shapes as well, so outfitting a model that fits your space is key.

Like fans, carbon filters are also characterized by CFM rating. In many cases, the CFM rating and ducting diameter of your fan and filter will coincide. Most of the time, carbon filters are at their peak productivity when positioned at the highest point in your grow space. This is where the most heat will accumulate.

Growing Cannabis Indoors vs. Outdoors: 3 Key Differences

A temperature controlled, fully ventilated space outfitted with several fans and a carbon filter exhaust is capable of removing nearly 100% of the odors in your grow space. What this setup cannot eliminate on its own can be easily supplemented with an odor eliminating spray or gel. Furthermore, carbon scrubbed environments can bring the airborne bacterial counts in your space from a whopping 10,000 parts per million (ppm) all the way down to as low as 30ppm. Your local hardware store and/or hydroponic supplier should have everything you need to implement a similar system into your own garden.

Remember to always be courteous when growing indoor cannabis and understand that the odors associated with this hobby are not equally pleasing to everyone. Employing any one or combination of these systems will not cost you too much out of pocket, and the investment at the end of the day should pay itself over in the silence of your unhindered friends, family, and neighbors.

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Patrick Bennett

Patrick lives with his wife and daughter in Denver, where he spends his time writing, photographing, and creating content for the cannabis community.

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