Tips & Tricks To Prevent Marijuana Odor

May 24, 2021

Marijuana has an undeniably, strong, unique smell that anyone can recognize. How many times have you been out and suddenly you were hit with it? I am pretty sure you were 100% aware of what it was you were smelling. This odor is appealing to some, however, it can completely blow up your spot in the wrong way if the wrong people catch a hint of it coming from your grow room.

With each passing day,  marijuana is becoming more and more popular worldwide as people begin discovering its medical benefits or enjoy it for a real high. We now have more people growing marijuana indoors than ever before so there is a pressing need to help growers learn to cover up the odor these plants give off. The smell while growing marijuana is what makes the practice so risky since the last thing you need is this to get the attention of people living in your area.

A grow room is bound to kick up a serious amount of potent marijuana odor, so attempting to grow without knowing how to properly deal with heavy odors could cause you to end up being a target for robbery or worse getting in trouble with the law. However, masking the smell can be a challenge. Your approach varies based on the size of your grow space. With a small grow space that has only 1 or 2 plants, it is possible to mask the smell much easier. This is definitely not the case with big grow areas because you literally need to scrub the air.

Get more tips on growing your own marijuana when you download my free grow bible.

Odor is a big deal. So, if you are planning to grow indoors, this article will be informative and teach you how to neutralize odors the best way.

Great ways to prevent marijuana odors Vent

Now that we are clear about the fact that marijuana odor is the main reason for growers getting caught, we need to explore the means to prevent this from happening. You should be able to enjoy a good high without your neighbors putting the obvious pieces together that will lead to you getting exposed. We all know that people love to run their mouth about who is doing what so let’s give them less to talk about, especially when it something as sensitive as growing marijuana.

So, not only do you want to ensure your grow space isn’t giving you away by emitting a potent smell, you also want to be sure you are not talking about it.

Here are the causes of potent marijuana smells and how you solve this problem:

Your vent fan is lacking a vacuum

Fans are necessary for your grow space because they can be used to remove the air from the environment. Take the time to properly position the fan so that it functions as a vacuum in your grow space. Basically, this is the way you will know that all the air is only leaving through a filter.

One way you can know that you created an adequate vacuum is by placing a thread in the opening of the grow space and keeping the door open just a little bit. When you notice the thread being sucked back into the room, then you now have a good vacuum. With any other results, you know not that the cannabis smell is going to escape your grow room through cracks and holes in the space.

It is essential that your space has the right amount of ventilation at all times.

Your vent fan is lacking a vacuum
Vent fan in a grow room

For a more detailed breakdown, you will want to divide the number of lamps by the number of watts by 2 which will equal the air outlet. For example: for 5 x 600 watt you need 1500m2 outlet and 750m2 inlet. When you multiply 5 x 600, you get 3000 then divide it y 2 which equals 1500m2 air inlet. Combine the vent fans to one controller to make sure you don’t end up activating just the air inlet. When you only activate the air inlet, it will result in too much pressure based on the conditions in the various parts of your marijuana grow space.

Not having the right filter

You don’t want a vent fan that is too small because your crop could easily be discovered by nosy neighbors. For example, a vent fan that measures 1500m3 will need a filter that is adjusted for 1500m3. For the absolute best results, change your filter to be 20% more volume than the vent fan. Filters have active carbon that will neutralize negatively charged odor ions.

Filters that are too small result in the vent fan forcing air through too fast so that the air doesn’t filter properly. Filters should never be used more than a year because it will get to a point that it no longer works right.
While you have to ability to switch out the carbon filters on your own, this can get tricky since it requires professional equipment such as a vibrating plate to spread the carbon in equal proportions. Don’t take the chance – just get yourself a brand new filter.

Not having the right filter
Carbon filter

Exhaust leaks

It is easy for a single leak to go unnoticed. Something like this could seem small, but it could be the reason for a very potent marijuana smell being released.

If you have one of those filters that are connected to a vent fan with a hose, then you’d want to make sure it is properly fixed with clamps. Always check the hose to make sure there are no holes. Insulated tubes require particular attention due to the inner aluminum tube having small holes in it. Attach the inner tube to the flange first since it connects much easier. Then you can connect the outer part of the hose with a clamp and secure it to the box.

Systems that help mask the smell of indoor marijuana growing spaces

Odor neutralizers

These are used to cover up marijuana odors. Because odor neutralizers are so potent, they can actually affect the taste of buds after some time.  We never suggest putting these in your grow room while the plants are flowering. But, you can use odor neutralizers that have a very potent aroma to stop smells from spreading outside the space. However, if you are interested in scrubbing the odor from the air, this is not the way to get that done.

Good luck if you plan on using wall plug-ins and sprays to deal with cannabis odors because the odds that they will mask the smell for long periods of time is very slim. Even more, these products have an adverse side effect as they could potentially mess up the natural smell of marijuana plants.

You will need an odor neutralizer that is capable of being consistent throughout your plant’s various growth cycles since the plant never stops emitting its smell while growing. Here are some solutions to this problem for those cultivating in a small grow room.

Ona products

Ona gels for marijuana odor

Ona products are a great solution that  have been on the market since 1995. They work well in hydro grow systems.  Ona is available as a gel, block, and mist product. Initially, both Ona Gel and Blocks were created with the intent to manage the foul odor inside of sewage facilities. Once people began to realize just how well these products reduce neutralize strong odors in general, they became more readily available.

Ona gels

Ona gel is available as small gel cubes that reduce unpleasant odors and replace it with a more preferred scent. These little cubes will successfully do their job until they are completely dried out. It is common to put them in the air vents which is a great way to make sure air is always filled with an enjoyable scent. There are multiple scents to choose from.

Ona blocks

These are not all the different from Ona gels except they are actually 170-gram tablets that you leave out in the grow room.

Ona mist

Ona mist is a spray that reduces smells very quickly and can be used for this purpose in your car and living space. As an extra bonus, this product is 100% organic and can be trusted to use around children, food and pets.

More about Ona products

While these products are great at neutralizing odors fast, work well in small grow rooms and are simple to use, they do not last long. You will have to purchase new ones just about every 3 to 4 weeks. Various testing has proven that Ona Gel is best for masking marijuana odors so long as you do not have many plants you are growing in the space. With just 1 or 2 tablets situated outside of the grow space you can effectively cover up the scent.

Even though these products are great, we warn you not to put these inside near plants that are flowering.  Ona products could mess up the smell of your marijuana buds if place in the same space as the growing plant, hence the warning. Putting this product in your living room, for instance, is good enough to mask the smell from anyone who comes over. Again, remember that Ona products are only to be used outside of your grow room.

When eliminating the odor coming from the exhaust, a carbon filter is the best way to go. We will discuss more on carbon filters later.

Ona Gels, Blocks and Mist length of effectiveness depends on the humidity and temperature of your grow room. But to give you an idea of what to expect, several people have reported that they last anywhere from 4-6 weeks, which is actually a nice length of time.

The Neutralizer

The Neutralizer - marijuana odor

Another great product that comes highly recommended is The Neutralizer which has actually won awards in Europe for its effectiveness. It consists of essential oils that neutralize smells and replaces them with an enjoyable scent. It actually functions similar to regular plug-ins you buy at the store. The steps are simple and only require you to put the cartridge in place and plug it in.

Again, this is another product that is good for small grow rooms and can last as long as 5 to 6 weeks.

For very small spaces, you can purchase the condensed form which also lasts the same amount of time. And with both of them, you can get interchangeable cartridges.


Vaportronic - marijuana odor

Vaportronic products come in discs of either 6 or 12 grams that consist of Neutrox Gama. The cool thing is you can program these discs to operate at different times with up to 5 discs at a time. These are called EZ disks which require a D battery for you to use it.

These discs can last you almost two months and are perfect for small grow rooms as well. The scent they give off is a lovely pine or eucalyptus smell.

Air purifiers

Air purifiers to help with marijuana odor

Who doesn’t like to have fresh, clean air to breathe in their environment? A ir purifiers are easy to find, and many claim to remove unwanted smells via a filter.

While air purifiers may be great to rid your home and overall environment of unpleasant odors, there are questions about how effective they are for eliminating potent marijuana smells in your grow space. Well, as you may have guessed, the answer is not very effective.

There are good air purifiers on the market that will get rid of certain odors in the air, but this just won’t cut it for indoor marijuana growing. While it may remove some of the odors, you will end up needing something stronger to get the job done right. Now, some air purifiers do help remove bad odors from the air. However, they are only marginally effective. They simply are not potent enough to pull every smell from a grow room. Therefore,  we do not recommend only using an air purifier to get rid of odors in your grow room.

You are better off sticking to air purifiers for less potent scents and going with the big boys for that cannabis scent.

Carbon filters

Carbon filters - marijuana odor

Of all the products available to eradicate odors, carbon filters, also known as ‘carbon scrubbers,’ are by far one of the more desirable options for eliminating harsh odors when doing indoor marijuana growing. These are highly effective even when growing strains that are known to let off the strongest odor. Carbon filters literally scrub the odor from the air and neutralize all smells that come through.

When you want to neutralize the air leaving from your exhaust carbon filters are the way to go. Carbon filters are excellent for making sure there are no chances of a marijuana scent exiting the window or some other exit point and into your neighborhood. These are a sure way to keep your marijuana growing private and prevent you from getting into any trouble.

When using carbon filters, you are going to need a tubular air extractor that has the right efficiency for your particular grow room. When the air is removed from the grow space it goes through the filter that is full of little small active carbon bullets, then leaves out without any smell. Carbon filters are different from the other systems because it does give off a fragrance and will only remove all odors from the space. These can be purchased in various sizes so you can select one that is perfect for your particular space.

Carbon filters are very reliable, simple to maintain after you get it set up, and they will last you a long time!

They use activated carbon to consume the odor from the air that is forced through the filter. You have to actually create a way for the nasty cannabis odor to be pushed into the filter by using a fan which will do this for you. To accomplish this goal, we suggest you get a carbon filter as part of your exhaust system that will contain an exhaust fan which will force the air out of your space. When the warm air is forced from the area where your plants are, the carbon filter will scrub all smells from the air at the same time.

Installing your carbon filter 

The first thing you need to consider is how big your exhaust is. You will find that several air-cooled cannabis grow lights have a 6-inch exhaust hole. If you are growing in a small space, then you will need to get all your stuff in 6”

The reason you want to get a 6” fan is because they have the ability to clear the air from just about any small grow space. Do not settle for a 4-inch fan because you will be sorely disappointed since they are not strong enough for a 6-inch carbon filter and to make it worse they won’t fit the regular air-cooled grow lights.

You only want to purchase 8-inch filters for commercial facilities that need very strong fans, and you will never be able to connect this to your standard grow lights.

Next, you should make sure the CFM rating matches the fan and carbon filter. The carbon filter’s CFM rating should be exactly like or even higher than the one you see listed on the fan. By doing this, you will have the best results and the carbon filter will only absorb the amount of air it can to scrub the odor out.

After you have considered these two things, install the fan and filter into your exhaust system. Pay very close attention to the provided instructions when installing your filter and fan. You can find many examples that will clearly show you how to properly set up your carbon filter in your exhaust system. When you have your carbon filter situated towards the back of the exhaust system, it will reduce the possibility of marijuana odors leaving the space during the flowering phase – when it is likely to be letting off the most potent scents.

Want to learn more about flowering and harvesting? Download my free harvesting guide now!

Stay away from ozone generators

Stay away from ozone generators marijuana odor

When talking about preventing marijuana odors, we must mention ozone generators because many are trying this method, but we have some warnings for you.

These are actually quite new in terms of systems used to neutralize odors in marijuana grow rooms. Ozone generators are said to eliminate smells, freshen up the air and destroy mold. Yes, you will find many marijuana growers giving praise to ozone generators for getting rid of odors, but we just disagree with using these for marijuana growing.

So, I know you are wondering why we advise against using ozone generators. Ozone generators are terrible for the atmosphere to the point that they are actually illegal in certain states. Now this should say something! Not only are ozone generators illegal in some places, but they are also not good for you!

Below you will find some links that will lead you to more information about ozone generators and why they aren’t good for you. Some organizations that have suggested against them include:

Some growers swear you can safely use ozone in your grow room by venting it from the space ensuring that it only gets into the exhaust. We say why take the risk of using ozone when a carbon filter works just as good without the possibility of causing health problems.  You and your family are safer and better off without it.

Feeling confident to grow your own marijuana? Visit my shop and choose from our wide selection of high-quality marijuana seeds.

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FAQs About Masking Marijuana Smell

How do you know when using a vacuum is enough to prevent cannabis odor?

Try placing a thread in the opening of your grow space and make sure to keep the door open just a little bit. If you notice the thread being sucked back into the room, then that’s a good indicator that you’ve got a good vacuum.

What can I use to neutralize the air leaving from my exhaust?

Carbon filters are the way to go. They are excellent for making sure there are no chances of a marijuana scent exiting your window or some other exit point and into your neighborhood.

Can I use odor neutralizers during the flowering phase?

It is not recommended to put odor neutralizers in your grow room while the plants are flowering. As they are so potent, they can actually affect the taste of buds after some time.

Growing cannabis like a pro only requires practice and learning. Get started with my blog.

Which of these tips have you tried to mask the smell of marijuana? Please feel free to share your experience or leave questions below!

Happy growing!


The founder of I Love Growing Marijuana, Robert Bergman, is a marijuana growing expert that enjoys sharing his knowledge with the world. He combines years of experience, ranging from small-scale grows to massive operations, with a passion for growing. His articles include tutorials on growing... [read more]


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  1. By jim ,07 Mar 2014
    Would this work just running it buy you see what you think first grow just putting information that I have collected for my own plan What I want is a very simple setup up thinking deep water culture 12 or […]Read More
    1. By GrassMaster ,16 Aug 2014
      Jim, you have many questions in your post. Let me start at the top and I'll do my best to answer them all. First you open up with the statement, "What I want is a simple setup" followed by, "deep […]Read More
  2. By Bi Linnert ,24 Jun 2014
    nice site, enjoyed roaming around a bit. Question: Is grow boost used in addition to "normal" flower nutes? I typically use General Hydroponics (flora-micro, flora-grow, flora bloom)
    1. By GrassMaster ,16 Aug 2014
      Yes, a bloom booster is used in conjunction with your flowering nutes. Get to know the variety of plant that you are growing. Every plant goes through growth spurts during flowering; each one differently. Learn to time the addition of […]Read More
  3. By Poco ,10 Nov 2014
    Sorry - but your rule for outlets makes no sense to me. Your formula yields 1500m2 air outlet. What exactly do you mean by "air outlet"? Is that the vent size? It would crazy huge = nearly 39m x 39m. […]Read More
  4. By Brian ,29 Nov 2015
    Hi Im trying to grow one plant in a basement bedroom. Im the only one who uses the basement in my home. Will keep door closed and I am hoping that leaving good odor removing automatic air fresheners will make […]Read More
    1. By latewood.ILGM ,01 Dec 2015
      Brian, You are going to need a carbon filter with a fan to keep the smell down. In order to keep plant smaller, yiled lower, and be more tame; You use small posts. 1galoon to 6 liters pots will do […]Read More
    2. By Redeye ,30 Mar 2018
      No contact or sale info provided
  5. By Ron ,30 Nov 2015
    Hi Brian, air fresheners really dont cut it when in full flower, I find the best method is by using an ozone generator , no smell at all, but do not go in your room when the ozone generator is […]Read More
    1. By latewood.ILGM ,01 Dec 2015
      You should not have an Ozone generator even in the same room as plants.
      1. By Brian ,01 Dec 2015
        Thanks for replies guys, im new here=) I am starting at one plant only as a beginner, i trust the seeds im getting from this website will be female I am researching air purifiers that have Active carbon pre-filters, […]Read More
        1. By Jennifer ILGM ,26 Apr 2016
          Hi Scoot, Like the article says not only are Ozone generators terrible for the atmosphere, but they are also not good for you. And besides it can affect the taste and smell of your plants.
          1. By Rick ,23 Oct 2017
            I would disagree if the ozone generating plates are inside with the exhaust stream inthe fan ducting pipe. No ozone in the room that way. The very small amount of ozone produced will rapidly break down outside and have no […]Read More
  6. By latewood.ILGM ,01 Dec 2015
    Grassmaster, I like your post, and for re: We call these growth spurts as cycles. My friend Zandor wrote a great article at thegrowreport years back. Search for it. It has a great breakdown and can help you recognize these […]Read More
  7. By latewood.ILGM ,01 Dec 2015
    Poco, Let me see if I can explain this. The fan is run whenever you need to exhaust heat or humidity into your grow space, exchanging the hot air with fresh air. This is controlled by a temp/humidity sensor and […]Read More
  8. By latewood.ILGM ,01 Dec 2015
    I meant to say above... The fan is run whenever you need to exhaust heat or humidity out of your grow space, exchanging the hot air with fresh air. And to clarify; Fans are CFM cubic feet per minute. So […]Read More
  9. By latewood.ILGM ,03 Dec 2015
    Brian , My best advice to you is to do your research and buy the filter you feel would do the best job for you. Since we are not a product testing lab, we cannot truly tell you which unit […]Read More
  10. By Dell ,07 Apr 2016
    What are your thoughts on a grow medium like MegaMulch with the seed in some pete. Grown in a greenhouse
  11. By latewood.ILGM ,08 Apr 2016
    Well, I have never used MegaMulch. You can grow in any medium if you have grow experience. There is no reason why you cannot be successful using this medium. It may not be optimum but, you might do well. It […]Read More
  12. By Ron ,11 Apr 2016
    I'm a first time grower and bought a ozone / uv / and regular filter will that take care of the odor from my plants. Thank ron
  13. By G ,18 May 2016
    I would like to do a indoor set up like two and half feet area , I would like to know what I need . Currently I have 9 set up 10 inch pots . I have 2ft floresent lights […]Read More
  14. By latewood.ILGM ,24 May 2016
    Ron, Ozone generators are good for cleaning stale air. You do not want an ozone generator in your grow room. you will need to place it in another room. I suggest you join our grow support forum, earn the right […]Read More
  15. By latewood.ILGM ,24 May 2016
    G, Sounds to me like you have way more pots and plants than adequate lighting. I suggest you join the main forum and that will put you in touch with many experienced growers and experts, who are willing to help […]Read More
  16. By Shadow ,21 Jun 2016
    I wanted to return email to Robert Bergman or someone who is real and would give me an accurate email address to use for my questions
    1. By latewood_ILGM ,21 Aug 2018
      The emails provided are accurate, and get posted anonymously on the forum for all the help with :)
  17. By Maci ,28 Jan 2017
    We tried twice to buy seeds, both shipments were intercepted by the DEA. We got empty envelopes with letters stating this was a big no-no. What do you do differently to assure I get the seeds should I buy from […]Read More
    1. By latewood_ILGM ,21 Aug 2018
      Maci, I have no idea if you were ever satisfied on this matter but, I can say that we guarantee all seed shipments and if your seeds get confiscated, we send another order. That is about all we can do. […]Read More
  18. By Chronic craigo ,16 Mar 2018
    Love it. Very insiteful. Helped quite a bit. 420 love
  19. By Steven ,02 Jun 2018
    Anyone ever use ozone lamps? Ozone output is quite limited, perhaps a bit stronger than UV lamps. Fans blow towards them and anything reaching them is removed.
    1. By latewood_ILGM ,21 Aug 2018
      Steven, Ozone products can be harmful to Cannabis plants. Be careful what you choose to put into your grow room. ;)
  20. By Lance ,17 Aug 2018
    Very informative will it be a good idea to get all my equipment and tools needed first so I'm set up and ready to plant indoors?
    1. By latewood_ILGM ,21 Aug 2018
      Lance, That is a good idea. ON the other hand; All you have to be mindful is to not plant seeds before you are set up. So as long as you are set up before starting seeds, it does not […]Read More
  21. By Al ,25 Jul 2019
    I don't understand the new Hybrids ?
  22. By Vic ,27 Jul 2019
    I love getting info from you. I like the weekly news you send out. Very helpful. I’m sure i will have questions later as i grow. 👍🏿
  23. By Hooppie ,27 Sep 2019
    I go to the local compost recycling site and get the stinky most robust mulch and spread throughout my property with a grass seed Spreader. Neighbos think the mulch stinks. GREAT Luve in NEWVA be Grow all crops outside, harvest […]Read More
  24. By Kyle c ,05 Feb 2020
    Ozone is new????? This was the best way in the 90s to eliminate smell. I dont recall seeing a carbon filter before 2000.
  25. By Jo ,06 Jul 2020
    Are there grinders on the market that grind an ounce at a time? Most only do a few grams. if you are making oil or tinctures you need a bigger volume. Don't want a $2000 unit though.
  26. By Glenn ,02 Sep 2020
    What’s the best plants to grow inside with the least smell ?
  27. By Randy ,08 Apr 2021
    Can't wait to check out your booklet

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