The two main reasons to seal a grow room are to keep bugs and pests out while also maintaining negative pressure so that your Cannabis Air Intake Filter can do its job.

For this grow the first line of defense is properly sealing the room. The second line of defense is grow tents placed inside the room (4’x’8 for flowering and 4’x3′ for veg).

Materials Needed

• GreatStuff Expanding Foam – Pest Blocker (for large gaps)
• Alex+ Caulk or Silicone (for small gaps)
• Weatherstripping gasket (sides and top of door)
• Under Door Seal
• Frosted Window Stickers

Before You Seal your Grow Room

Before sealing off the room make sure you have:

• Air Intake/Exhaust
• Power Outlet (a typical 15A residential breaker = 1800W)
• Water Line (for DWC this is essential, carrying water sucks)

Frosted Windows

In the Grow Room Window Air Exhaust article, I discuss using blinds on any windows that you will be pushing air out of. For both aesthetics and stealth. My grow room door has a window on it, and the adjacent laundry room has a window that could let someone look into the grow room.

For increased privacy I used stick on window frosting, which can be found super cheap on amazon.

Cut to size and use a spray water bottle to apply to the window. There is no adhesive used, the suction holds it to the window for a clean quick install.

Sealing Grow Room Gaps

There is a reason that expanding foam is sold under the trade name “the great stuff”. It is pretty great and they have a pest blocking version that is formulated with ingredients that help keep bugs and small rodents from eating their way through the foam. This stuff is amazing for sealing holes up to 5″ in diameter.

For smaller gaps use Alex+ caulk or a silicone to seal.

I will be using grow tents in this room as a second line of defense against pathogens and bugs. For this reason I am not that concerned with how this looks. The goal is just to seal any cracks and gaps to keep bugs out.

Sealing a Grow Room Door

When sealing a door divide it into two parts. (1) The sides/top and (2) the bottom of the door. Typically the side/top seals go on the frame while the bottom seal goes directly on the door.

(1) I used Weatherstripping gasket for the sides and top. Clean the surface with a mild detergent before applying for max adhesion.

(2) For the bottom I found this excellent under door seal infused with Diamotaceous earth. Each of the fins that fit tightly against the threshold is coated with diatomaceous earth, a natural, completely non-toxic substance made up of the fossilized shells of tiny, aquatic diatoms. These abrasive particles form scratches on the exoskeletons of any bugs that manage to squeeze under the door seal and this damage kills them.

I had to shave off about 1/8″ from my door for a perfect fit. I think home depot is the only place that sells this stuff, I could not find it on amazon, though there are many non Diatomaceous versions if you don’t have an old bug-filled house as I do.

That is about it. Once you have your door and any cracks sealed you are ready to either paint the room or install your grow tents.

I found grow tents to be an economical way to build dividers within the room for the flowering and veg portions. (assuming you don’t have a dedicated grow room). The grow tents are also a second line of defense against bugs and can be taken down and re-used if you move in the future.