smells, smoke or odor on white background

5 Ways to Odor Proof Your Indoor Grow

Are you growing weed indoors under the radar? Are you growing in a spare room? Stealth or not, smell-proofing your operation is always a concern. 

Cannabis plants produce some exceptionally intoxicating and pungent aromas, which tend to escape the confines of any grow tent. How do you grow weed without the smell?

In our experience, no cannabis grow is truly smell-proof, but that doesn’t mean there aren’t solutions for reducing the smell. Here are a few options for keeping that tell-tale odor under wraps.

1. Analyze Air Circulation in the Grow Room

A healthy grow room requires proper air circulation. That means new air flows in and stale air flows out. 

air ducting going into an attic
Understanding the flow of air through your grow room, can help optimise the entire system.

At the very least, this requires a simple vent, usually positioned at the bottom and top of the grow tent. More advanced systems will include inline and exhaust components, filters, and oscillating fans. Typically new air enters below your plants, while old air exhausts above the canopy.

But if you are trying to get that potent smell of weed under control, you’ll need to analyze the air circulation. Where does the new air come from, how does it flow through the system, and where does it exit? 

You may also want to take a moment to calculate the baseline cubic feet per minute (CFM) required for your space. As in, how much new air per minute do your plants need? If you are adding components into the air flow, you’ll need this base number to choose the right equipment.

The base CFM calculation is width x depth x height. 

As you add different components into your system, like grow lights, ducting (and duct bends), and exhaust fans, these are added to the equation.

Sketch it out on a piece of paper. Don’t forget to consider the impact of oscillating fans, heaters, and/or air conditioners if you are using these in space. Once you understand the movement, you can adjust and improve the airflow towards where you want it. 

Use ducting to direct the stale, aromatic air through filters towards a suitable exit (outdoors or into a non-living space). By adjusting entry and exit points, moving around the oscillating fans, and considering the impact of heaters/AC units, you can better direct the exhaust towards the ducting and through a carbon filter system.

2. Use a Carbon Filter (aka a Scrubber)

Exhaust fans pull hot, spent air out of your grow tent. Paired with a carbon filter, they can also remove much of the odor caused by the volatile organic compounds (like terpenes) produced by your plants.

Carbon filters, sometimes called scrubbers, contain activated charcoal. This substance has an incredible absorption rate, possibly up to 33 percent of its weight (depending on the volatile compound). They are commonly used in both small-scale and commercial cannabis cultivation to reduce terpene-rich odors.

Carbon filters come in various sizes, depending on your grow room’s total CFM rating, including the base volume, plus accessories, exhaust components, and the heat emitted by your grow room lights. 

Filters come in four, six, eight, ten, and twelve-inch sizes. Once you have your final CFM rating, check with the manufacturer for the appropriate size.

3. Install an Ozone Generator

If you are serious about eliminating odors in your grow room, chances are you’ll need an ozone generator. A common feature in commercial grow rooms. They are increasingly more affordable and accessible for the serious and technically-minded hobby farmer.

You may be familiar with ozone, as it’s a natural part of the earth’s atmosphere, albeit one that we try to keep in check. It’s made up of three oxygen atoms (O₃), making it a powerful oxidizing agent. 

Ozone pumps are often used in hydroponic setups to help sterilize water. But ozone generators can also work for eliminating harmful or odorous molecules from the air. Installed on the exhaust fan, an ozone generator can reduce volatile terpenes from escaping your grow room into your house.

There are risks associated with ozone generators, especially in small spaces. Ozone is dangerous for your respiratory tract, and at higher levels, could even damage your plants. 

You’ll want to run the one generator for very controlled periods and ensure the grow room already has optimal ventilation. Ventilate well after using ozone in case localized concentrations are too high.

4. Add a Few Odor Absorbers

If you only have a few plants, there are simpler and more affordable methods than an ozone generator or carbon filtration system. Odor absorbers are one-time use products containing an odor-trapping formulation of chemicals. 

Much like a box of baking soda in your refrigerator helps reduce smells, these chemicals trap volatile airborne molecules as well.

Several commercial products are available, including packets of activated charcoal and buckets containing specialized ingredients like chlorine dioxide. 

These aren’t 100 percent foolproof, which is why they are best suited to a small-scale operation with only a few plants. But, they work well in combination with the other options on this list.

4. Choose a Less Pungent Strain

If you’ve any experience working with cannabis, you’ll already know that certain strains come with significantly higher terpene levels than others. For example, some of the most aromatic strains have kush, skunk, or sour in the cultivar name. 

So, set yourself up for success by choosing a low-odor strain from the start. Several seed banks, including Royal Queen Seeds and Zamniesa, carry supposedly less smelly options. A few of these strains include Northern Lights, Jack Herer, and White Rhino. 

5. Invest in a Grow Cabinet

A grow box is a final option for anyone wanting to grow just a handful of plants. Sometimes called a grow closet or cabinet, these are all-in-one systems that come with all the grow room fundamentals installed, including lights, fans, and climate controls. Essentially, you plug in the box, and you are ready to grow.

Importantly, stealth boxes incorporate a carbon filtration system, which promises to reduce most of the odors produced by the plants. While similar in many ways to a grow tent, they are specifically designed to fly under the radar, which means they are quiet, efficient, and produce little to no odors. 

Tucked into the corner of a basement, garage, or even living room, they should attract minimal attention by keeping the tell-tale signs of cannabis under control.

Take a Holistic Approach to Reduce Odors from a Grow Room

If you take any ideas away from this how-to article, the most fundamental is that your cannabis grow tent will always smell – at least a little bit. 

But, you can reduce the pungent smells of your plants through a multi-pronged approach. 

Where should you start? Investigate your airflow, install carbon filters, and add an odor absorber. Every added level adds a new layer of odor control.

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