Cannabis plants get smelly and although most growers love the beautiful smell, having your living space constantly smelling can quickly become an inconvenience for you and people around.
Depending on the number of plants you are growing, the odor will be more or less difficult to control but even if you intend to grow one plant you should plan ahead and have a solution for it.
When does it smell?
Plants that are in the vegetative stage won't smell much unless you get very close to the plant, this is due to the fact that the plant has not started the production of terpenes which is responsible for the strong aromas produced by the cannabis plant.
As soon as you transition to the flowering stage, the plant will start to increasingly produce terpenes, filling the room with a nice smell. From this point, it will only get worse as your buds grow in volume.
Harvest and post-harvest is also one thing to consider, as one of the most smelly part of the growing process is when the plant is drying and being trimmed.
Cheap ways to control the odor
Ventilation: Having adequate ventilation allows air to circulate and keeps humidity levels under control, this will help but probably won't be enough if you want to get rid of the smell.
Gels: Some gels such as Ona will absorb part of the odor molecules and will release other aromas just like the magic tree in a car. Although this is a good back-up solution, take note that it will only mask the odors and can even make un unpleasant mix.
Carbon filters are by far the best option available to control the smell of your grow room. The active carbon will trap the odor molecules going through the filter and will exhaust fresh air.
Not only will it purify the air from odors, but it will also capture dust, hairs, spores and other volatile components that can affect your grow. For this reason, the carbon filter or "scrubber" is a very good investment not only for stealth but also to optimize the results of your crop and reduce risks of mold, insects, and fungus.
There are many different sizes of carbon filters, the bigger they are the more they can purify. Just like fans, the amount of air purified per minute is calculated in CFM.
Carbon filters can get really big and heavy so make sure your grow room can fit it. Most growers will suspend the filter to the poles of their tent in a top corner, this is because most of the heat is located there and the carbon filter being part of your ventilation system you want to exhaust as much hot air as you can. For this reason, make sure the tent is able to support the weight of the filter.
Make sure you calculate the amount of CFM you need to exhaust and choose a fan and filter combo accordingly but here are some recommendations:
- Use a 4" Carbon filter combined with a 4" fan for small spaces such as 2x2, 3x3, 2x4. These will generally range between 150 and 250 CFM which is more than enough.
- Use 6" carbon filter combined with 6" fan for medium spaces such as 4x4, 5x5. These will generally range between 400 and 550 CFM which again is more than enough.
- Use 8" carbon filter combined with 8" fan for bigger spaces such as 4x8 or 10x10. These will generally range between 700 and 1000 CFM depending on the brand and quality.
Sometimes having the air going through the carbon only once can still leave a very subtle smell. This is especially true if your exhaust the air at full speed and the fan CFM is greater than the carbon filter CFM. One of the best ways to solve this is by having the air re-circulate. This means the air that goes out of your tent is exhausted inside the room where the tent is located. By having the air re-entering the tent once again and going trough the carbon filter perpetually will ensure the odor is completely under control.
With the right temperature control and air circulation, your carbon filter can purify 100% of the odor and additionally get rid of most unwanted particles in the air. So even if you have to spend a few bucks on this, it will easily repay itself over time as most carbon filters can last for several years if used correctly.