Tips on Indoor Gardening in Sealed Grow Rooms 

One of the most beautiful, and challenging, elements of indoor cultivation is that of the environmental control and manipulation of one’s grow room. While it’s quite evident that outdoor gardeners enjoy the pleasantries of working under blue skies, their crops are still at the mercy of Mother Nature. Elemental forces such as rain and humidity often effect the quality of one’s harvest. This notion is particularly true as compared to indoor gardening operations, where advancements in sealed grow rooms are giving growers almost unlimited control on garden environments.

Truly passionate CEA horticulturalists take a great amount of pride in grow room design. They also appreciate the fine balance it takes to create an artificial environment in which plants thrive. For these indoor enthusiasts, cleanliness, sophisticated equipment, air flow, humidity levels, temperature balance, and proper CO2 levels can bring as much satisfaction as a good looking crop. The same can be said about the utilization of cutting-edge cultivation technology and hydroponics equipment. Along this line of thought, there is perhaps no more explicit example of a perfectly balanced synthetic cultivation environmesealed grow rooms nt than that of a sealed grow room.

Sealed grow rooms are those rooms that have no air exchange between the interior and exterior of the cultivation space. Ideally, they are sealed tight from any air or light leaks. In the creation of this independent ambient atmosphere, indoor growers have control over temperature, humidity, and CO2 without having to consider (in much detail) environmental constraints of the outdoors. Growers are able to accomplish this feat with the use of advanced environmental controls and proper grow room infrastructure. With these things considered, for those interested in building a sealed grow room, here are a few tips to help you on your way:

Air Conditioners

As sealed grow rooms don’t feature the traditional air exchange elements of intake and outtake fans, they require air conditioners to create an ideal environment for indoor gardening. For most cultivators, the use of a mini-split AC system makes the most sense for sealed rooms as they don’t require large holes in walls. Because, traditional home AC systems and window units are much more difficult to work with concerning light and air leaks—they generally require large holes in the grow room walls. Conversely, mini-split AC systems feature a compressor that operate outdoors with thin copper tubing running into the room to a head unit which expels cool air. This copper tubing is less than an inch thick and is easily ran into a room and sealed off with some caulk.

CO2 Systems in Sealed Grow Rooms 

Since sealed rooms don’t have the aforementioned elements of air-exchange seen in traditional indoor gardening, CO2 injection systems must be implemented to supplement for the loss of fresh, CO2 rich air. However, CO2 enrichment is the primary motivation for cultivating in a sealed environment—as CO2 levels can be precisely controlled and monitored in these environs. Even more, average, ambient CO2 levels in grow rooms range anywhere from 300-500 ppm, while indoor cultivators can synthesize a stasis of CO2 levels around 1500 ppm. With these notions in mind, it is much more difficult to maintain an ideal CO2 equilibrium (not to mention gardener’s will waste far more CO2) without a properly sealed grow room.

Bedrooms and Basements

In order for a sealed grow room to proper functionally with a delicate balance of air conditioning and CO2 injection it must be sealed properly. For indoor growers cultivating in bedrooms and basements, sealing a garden area for light and air leaks is a relatively simple task.

One of the largest obstacles to overcome in sealing a basement or bedroom grow room is that of windows. For starters, many cultivators like to cover an entire window up with a piece of soundboard or plywood. This added layer of protection will help lessen exterior noises and will add an extra layer of insulation from outdoor environmental elements. After this initial layer of protection is placed over the window, its best to cover the entire wall (with the window) with a layer of photo reflective “panda” film.  This material will help further insulate the room from light and air leaks.

Even more so than windows, doors entering into basement or bedroom grow rooms pose a serious impediment when trying to completely seal the space. Because, as cultivators generally need these doors to access the garden area in question they cannot simply cover them up with  soundboard and panda film. That being said, the use of “zipper-doors” has long been a favorite for indoor growers looking to seal a door from light and air leaks whilst still keeping the door functional. Zipper-doors function to keep an air and light leak proof plastic layer over a doorway while still allowing access to an indoor garden space.

Grow Rooms Inside of Rooms

Many indoor cultivators opt to build free-standing grow rooms within rooms. There are a number of motivations for this, but they are mostly involved with lessening the impact of an indoor grow on a home as well as creating a more efficient growing environment for the area in question—namely that of garages. That being said, if an indoor grower chooses to build a room inside of a room, it will pose more problems with properly sealing the area.

As fabricated grow rooms generally don’t feature dry-wall, insulation, and professionally mounted doors they lack many of the light and air control features present in a bedroom or basement constructed by a professional builder. Therefore, there are a couple of routes to take in sealing these fabricated grow rooms. First of all, one can build out the entire frame and ceiling of the room in a fashion similar to building a home. Once this frame is built, the entire thing can be wrapped in 6mm black plastic and carefully stapled to the frame. This thick plastic will ensure that there are no light or air leaks. Secondly, one can cover their walls with plywood as would be seen in traditional home building scenarios. While an entire dry-wall process is not necessary for these rooms, caulking up all the cracks between plywood boards and the floor and walls will remove all elements of light and air leaks.


This article originally appeared in the September 2017 edition of Maximum Yield Magazine.