You can smell a single flowering marijuana plant grown on a mountain top from 20m away when the wind blows a certain way. Imagine therefore the concentrated smell of 20 plants grown in a spare room in a populated area! Its not for nothing that this plant is nicknamed “skunk”.

How to get rid of the smell of cannabis from your indoor grow room

As the pervasive smell of budding cannabis is a giveaway of any illegal grow, odor removal has to be a priority. Here are some tried and tested methods of minimizing smells:


  1. Choose your strain carefully

Whilst many tokers quantify quality by smell, there are some strains out there which still pack a punch with a less identifiable scent. The following are a few notable varieties which factor less on the nose factor:odour control cannabis


  1. Carbon Filters.

odor control cannabis grow room

Probably the best way to remove smells from your marijuana grow room. These work by connecting the filter to your extractor using flexible piping, and pulling the air through active carbon on its way to the outtake hole. The carbon eliminates  odours by neutralizing them. We’d consider them essential to any indoor grow room and recommend buying the best you can afford. Match the carbon filter not only to the size in diameter of your extractor (eg a 5″ exhaust fan needs a 5″ carbon filter) but also look at the cubic meterage/hour the filter is gauged for. Work out the cubic size of your area and buy accordingly.

for example, :

  • RVK A1 100mm 160m3/h extractor fan = 100mm 225m3/h carbon filter
  • RVK L1 125mm 325m3/h extractor fan = 125mm 300m3/h carbon filter
  • Prima Klima 125mm 203/360m3/h extractor fan = 125mm 450m3/h carbon filter
  • RVK A1 150mm 425m3/h extractor fan = 150mm 400m3/h carbon filter
  • RVK L1 150mm 680m3/h extractor fan = 150mm 650m3/h carbon filter
  • RVK A1 200mm 750m3/h extractor fan = 200mm 760m3/h carbon filter
  • RVK A1 315mm 1350m3/h extractor fan = 315mm 1200m3/h carbon filter

Don’t connect your carbon filter (carbon scrubber) directly to the exhaust fan but use a short length of ducting between the two pieces of grow equipment. The ducting absorbs some of the extractor’s vibrations which can otherwise cause the carbon pieces in the filter to settle at the bottom, thus reducing efficiency.

Carbon filters are most effective when humidity is less than 70%, but in flowering you should keep your humidity low in any case to avoid the possibility of molds and bud rot. Replace in accordance with your brand’s recommendations.

  1. (Ozone Generators)

These produce ozone (O3)and a clean, hospital like smell. the extra O molecule attaches itself to the bad smells and neutralizes them . Run on a continuous timer with 30 minutes on, 30 minutes off. Place in the air-intake tubing (just outside the room itself) to allow for proper mixing of ozone and air.

HOWEVER you should be aware that these can be extremely hazardous to your health, and are illegal in many parts of the world eg California. As carbon filters do just the same job, why risk it?


  1. Ionisers

Work around a negative ion generator. The negative ions join with particles in the air (dust, smell etc) and then fall to the floor. You need to keep a clean grow room or this results in unwanted muck, which can have detrimental effects on the health of your plants. May be used in conjunction with other odour control products as not always 100% efficient. Place outside the grow area as there are reports of them effecting not only the smell of the finished marijuana crop, but according to some growers, the THC levels too. Even the best ionisers produce a small amount of ozone, and for this reason alone they are –


  1. Masking Agents

Some people suggest you can disguise the smell of marijuana cultivation using shop bought air-fresheners, Febreeze and so on –  with the added benefits of making your ONA GELhome smell good too. Unfortunately such tactics are only temporary, and sometimes contain chemicals that may be OK to inhale but not to be ingested .. ie don’t spray your growing buds with air freshener!

The best “masking agent” doesn’t cover the smell, but like the carbon in a filter, absorbs it: the Ona range of odour neutralizers chemically bonds with the molecules creating smells. Available in a variety of applications from gels to sprays, we’d advise not using them in the grow room itself (where they will remove the smell from your buds) but in conjunction with a filter at late stage flowering / drying / smoking.

Ona was developed for use in sewerage treatment plants, and its certainly strong enough to absorb most smells!  Remember to replace on a monthly basis.





  1. Home made odour controls

There are several DIY projects listed on the internet which can be cheaper, although not as effective as a manufactured unit. One version is a lidded bucket (with holes drilled in the lid)  filled with a mix of perlite and e.g. kitty litter.

We’d say though, UNLESS you are in an impoverished part of the world and income and availability make the more reliable forms of odor control an impossibility, factor in the cost of a decent carbon filter into your set-up costs. You can defer purchase until week 4 of flowering but without a legal permission to grow the risk of detection is simply not worth the skimping on this item.


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