The skunk is appropriately named. There are exceptionally acrid varieties of marijuana skunk that rival the stench of the live mammal. Thankfully, a lot of the skunk smell has been bred out of many of the myriad of hybrids that are now available, allowing the strain to be grown much more easily indoors. However, even the mildest strains of cannabis can have a considerable tell-tale odor that oftentimes must be mitigated if one is to grow indoors or out.
There are many ways to mitigate smell. The industrial-strength method, used by most larger indoor growers, is to utilize a can filter. This equipment utilizes a strong fan to pass air through a huge can of activated charcoal, often over 100 lbs. total, and the odor is absorbed from the air. There are two ways that a can filter can be utilized. The fan can be set on top of the can in the corner of the grow room with no other ducting. The air in the room is sucked through the charcoal over and over, effectively scrubbing all the odor-causing elements from the air. Some say that this method actually diminishes the aroma of the finished product after it has been dried and cured. (I kind-of doubt it. Odorous terpenes in the plant are not going to be affected by scrubbing the air. I could be wrong …).
The other way that a can filter is used is to scrub the air as it is exhausted from the room. This is not as effective as the method previously described because the air only passes through the charcoal once before it is blown outside. Larger collective gardens have found success by utilizing both methods simultaneously. (It is often necessary to add additional odor-mitigating measures when a crop is drying. Two can filters may be necessary during this phase). Smaller and less-expensive can filters are available for smaller grow-rooms.
There are number of ways other than the tried-and-true can filters that are often employed and are frequently up to the task. Some growers keep a mesh bag full of crumpled fabric softener sheets in the exhaust outlet. This covers up the cannabis smell, but it smells like someone is doing laundry 24 / 7. There’s a great, and inexpensive, product called ONA. It stands for odor neutralizing agent … and it really is. An $8.00 can is left open in the grow room, and another is kept in the exhaust outlet. It is surprisingly effective for about three weeks.
Companion planting is another good technique. Various shrubs are planted outside the house, near the grow room exhaust. Jasmine, rosemary, and peppermint are some favorites.
Some people cook a lot of stew, spaghetti sauce, soups, etc. during drying time and freeze everything in the vacuum freezer bags that they have for sealing the buds when dry. This provides lots of fresh-frozen foods during most of the grow cycle. Back in the early days of Dharma Producers Group, which ran a dispensary in the old Warfield building in downtown San Francisco, the growers covered the smell of the plants with stews and soups that were vacuum sealed, frozen, and then given to needy patients to take home.
A three-pound can of ground coffee and a crock-pot can fill the house with intense coffee smells for about a month. Turn the crock pot on low and add one coffee measure of dry ground coffee. It will smell for about six hours, at which time another dose is added on top of the first one. Keep repeating until the coffee can is empty and the crock pot is full. When the crock-pot full of dried coffee ceases to put out much odors, fill it with hot water. Viola! Three or four days of intense coffee smell. There is another advantage in the coffee technique that some growers might find welcome, especially if they would rather not have much interaction with neighbors. If one acts sufficiently nervous and jumpy to justify 24 hour caffeine consumption, the neighbors might choose to socialize with others who are more laid-back, so to speak. Just a thought.
One of the most inventive techniques I’ve seen is the fix-the-roof method. Most people know that horrendous gagging smell when a neighbor is having the roof repaired. It comes from the melted tar pots and completely stinks up about four square blocks. Our hero bought a tar pot and fixed his roof each year at about the time the super skunk plants in his back yard started doing their seasonal thing. After a few years, he had the thickest roof on the block. The neighbors thought that, instead of a backyard grower, he was merely a rotten roofer. He made it a point to complain about all the unfindable roof leaks every time it rained. The neighborhood kind of left him alone.
A final, not-very-related, thought comes to mind. The guy that developed the crock pot / coffee technique described above grew in a third-floor apartment. He once had a hydro spill that flooded his apartment and ran through the floor into the landlord’s apartment downstairs. The guy had the forethought to keep a large aquarium in his living room. He quickly drained it and, when the landlord arrived, began crying about his poor dead fish. The landlord assumed the water was from the aquarium and had no thought of going into the bedroom. From this point on, the guy kept a large supply of unwrapped rockwool slabs right beside his reservoir. He had another leak a few months later and the slabs soaked up every drop before it could go through into his landlord’s ceiling.