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You can’t miss the smell.
It’s pungent and very distinct – it’s the smell of marijuana.
Your grow room, whether it’s a free-standing building or in your basement, is pumping out that smell whether you want it to or not.
Recreational marijuana is legal in 10 states, including Michigan, which means there are a lot of people now growing cannabis for recreational use. While it’s legal, you might not want your home to smell like weed and don’t want people you don’t know to smell your crops in your outbuilding.
With all of this being said, you also want to avoid things that will absorb that smell.
Are there insulation and building materials that will hold that smell? Yes, there is, but some materials, like open cell spray foam in grow rooms, are getting a bad rap because of their composition.
Will Open Cell Spray Foam Absorb Marijuana Smell?
Here's the quick answer -- open cell spray foam doesn't hold onto any odors.
Now, let’s break it down. Open cell foam is porous, meaning water can move through it. Some people think that because of this, it might trap smells—like marijuana odors—in those pores. But that’s just not the case.
Foam insulation is actually a type of plastic that creates an airtight seal. So, those two facts together—the foam being plastic and the air seal—mean that odors can’t get into the foam in the first place.
On the other hand, materials like fiberglass or certain types of drywall are much more likely to soak up smells. Drywall is also porous, giving odors more ways to sneak through. That’s why you’ll notice the smell sticking to it.
At the end of the day, it all comes back to that air seal, which also helps keep the smell from escaping in the first place.
Marijuana Grow Smell Control
Now that you know open cell spray foam isn’t going to make the smell of your grow room stick around, here are some tips to help combat that odor.
Add a Carbon Filter or Carbon Scrubber
Carbon filters, also called carbon scrubbers, can pull odors out of the air and neutralize them.
These filters are especially helpful in neutralizing the air coming from your exhaust system, keeping the smell from spreading.
Use Odor Neutralizing Products in Your Home
While proper ventilation is key, it only goes so far—especially in the last six weeks of marijuana’s lifecycle when the smell is strongest.
Using odor-eliminating sprays or gels around your home, but not directly in the grow room, can help mask the marijuana odor.
Manage Temperature and Humidity Levels
High temperatures and humidity can make odor problems worse, especially during the blooming phase.
Leafly suggests maintaining the right balance of temperature and humidity for your plants to help reduce the smell.
Grow a Low-Odor Strain
If you’re looking to cut down on the smell even further, Grow Weed Easy recommends opting for strains that naturally produce more neutral smells, even when they’re fully mature.
The Best Insulation for Your Grow Room
Creating an air seal in your grow room is essential to maintaining the temperature and humidity you need to cultivate cannabis.
There are a lot of factors that determine which spray foam you should add to your grow room. If your walls are exposed, then you will want closed cell spray foam because of its durability. If you plan on finishing the walls, then open cell can be installed.
The key is creating an environment that will be easy to control and maintain so you’re left with a large, healthy crop.
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