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How to Remove Cannabis Smell from Indoor Growing. 2025 Guide

Step by step

Growing cannabis indoors offers many benefits, but also one major challenge: odour. How to neutralise the smell of cannabis in your indoor grow, what products really work and what mistakes to avoid so you don't end up fragrancing the entire neighbourhood — we explain it all in this post.

Why does cannabis smell so much?

It's no coincidence. The smell of cannabis is caused by terpenes, natural compounds that plants produce to defend themselves and attract pollinators. Some varieties produce a subtle aroma, whilst others smell like Skunk, Haze, gas, citrus, sweet fruits or spices... and some can smell overwhelminglyof everything at once.

This smell spikes during the flowering phase; if you properly channel the air extraction from inside the grow by filtering it through a carbon filter, mixing it with ozone, and ensuring negative pressure, you can greatly reduce the odds of odour escaping to the outside. If it smells outside the grow space, we recommend using odour-neutralising products such as Ona, Zerum, SinOL Strong or Neutralizer, especially at harvest time when the smell is strongest. You can also place them in the air outlets, after the filter and/or ozone.

You should bear in mind several factors that directly affect the odour of your grow:

  • High temperatures

  • High humidity

  • Poor ventilation

  • Grows with many plants in a small space

Indoor grow

Real solutions to eliminate cannabis odour from your grow

  1. Activated carbon filter: basic and essential

If you grow indoors, you absolutely need a good carbon filter. It connects to the extraction system and is responsible for trapping odorous particles before they escape outside.

  • Make sure the extractor's flow rate is compatible with the filter.

  • Replace it every 12–18 months (if it starts to smell, it's too late).

  • Don't rely on cheap filters if you want good results.

Here are our recommendations from Growlobby to get the filter right:

Can-Lite Activated Carbon Filters

Can Filters Inline Carbon Filters

  1. Properly-sized extractor

A good filter is useless if air doesn't pass through it properly. A powerful and quiet extractor is your ally for renewing the air and controlling odours, temperature and humidity. Don't cut corners here. You must control all air inlets and outlets in the room and make sure the pressure is negative so that all the air inside the grow exits through the system.

Soundproofed ISO-MAX Extractor

RVK Systemair Sileo Extractors

Prima Klima AC Extractor (1 Speed)

  1. Ozone generators (ducting only)

Ozonisers can destroy the molecules responsible for odour, but should never be placed inside the cupboard or grow room. Ozone damages plants and is harmful if you breathe it. It can be used in the extraction duct, after the filter, to finish the job.

Indizono Ozonisers

OzoKiller Ozoniser

  1. Odour neutralisers outside the grow

Odour-neutralising products help control the atmosphere in your home, hallways or nearby areas. Perfect to place near the cupboard or in doorways, but never inside the grow, or they will affect the final flavour of your buds.

Ona Gel Neutraliser

SinOL Liquid Neutraliser

Neutralizer Complete Kit

  1. Monitor temperature and humidity carefully

The hotter and more humid the environment, the more terpenes volatilise. Keep your grow in stable conditions:

  • Ideal temperature: 20–25 °C

  • Humidity during flowering: 40–50%

Using a dehumidifier and good cross-ventilation will make a real difference

  1. Scrubbing: recirculation with filter

In some cases, you can use a "scrubbing" system: recirculating air through an additional carbon filter within the same space without extracting it. It's useful when you can't vent air outside or want to reinforce filtration.

Indoor Grow Room

What if you don't want it to smell from the start?

At Growlobby, we advise you to choose more discreet genetics. Some varieties smell little even during flowering, like:

  • Northern Lights

  • White Widow

They're not miracle workers, but they can certainly help when discretion is paramount.

Mistakes that cause odour leaks

  • Using old or poor-quality filters.

Filters lose effectiveness with use; at Growlobby we recommend changing them every 12–18 months.

  • Using inlets without pressure control.

When more air enters than leaves, positive pressure builds in the cupboard, forcing air and odour out through gaps. Make sure your main extractor is more powerful than the inlet to maintain negative pressure.

  • Poor system assembly: loose joints and ducts.

If the extraction duct isn't properly sealed to the filter or extractor, small leaks can let odour escape. Use metal clamps or aluminium tape to seal all joints properly.

  • Overcrowding the cupboard or room with too many plants.

Be aware of your room or cupboard's extraction capacity; don't pack the space with too many plants or controlling odour will be very difficult.

  • Using dehumidifiers or heaters inside without ventilation.

Instead of neutralising, they just mix smells inside the cupboard or room. And worse: they can affect the final taste of your buds without even touching the plants.

  • Drying room without a filter.

Many people manage the grow well but forget about drying, one of the smelliest phases. We need active filtration for this stage; you can use drying boxes with extraction along with a smaller carbon filter.

  • Unexpected power cuts.

When the power goes out, the extractors shut down and odour keeps escaping. Having a UPS (Uninterruptible Power Supply) to keep the extractor running for at least a few minutes can make all the difference.

Conclusion

Eliminating cannabis odour indoors isn't a quick fix, but with the right equipment and some thought, you can grow in complete peace of mind. Invest in a good extraction system with a carbon filter, keep conditions under control and never let the smell give you away.