How to Build a Plywood Grow Box

Local Classifieds or Lumber/Homebuilding store:
Plywood 3/8″, 1/2″ or 3/4″
2×2, 2×3 or 2×4 Lumber for frame
Amazon:
2-3pc Heavy Duty T Hinge
2pc Barrel Lock
10pc Roller Locks (to help keep door closed)
500 Construction Screws 2 1/2″
1 Gallon White Paint (Glossy)
Paint roller
1-2 tubes White Silicone
Caulk gun
Circular Saw
16-24′ Weather Stripping (1″ thick)

Optional Light Blocker:
Black Coroplast
Hot Glue Gun
2x 120mm Box Fan

Step 1: Design your box to fit your grow space

Pick a size. For flower only rooms we recommend a square box (3×3′ or 4’x4′). If you will be including a veg room a rectangular box works better (3×4′ or 4×5′). This method of growing will require a minimum height of 5′, the doctor recommends 6-7′ height if possible.

Step 2: Create a door

Make your door as big as possible, you will thank yourself when trimming leaves. Use heavy-duty T hinges.

Step 3: Paint and Seal Box

The doc recommends using glossy white paint. Conventional wisdom suggests the use of matte paints as they reflect slightly more light. This benefit is outweighed by the fact that matte paint is porous and not a good choice for a humid environment. White silicone caulk is used to seal the edges.

Weatherstripping and roller locks are used to create an airtight seal at the door.

Step 4: Install an Air Filter

Air intake filters are so important that I have an entire article dedicated to them. After trying a few types I’ve found that furnace filters are the most cost effective option. I use black plastic to create shutters that block light from getting in through the white filter.

Step 5: (Optional) – VEG room

Vegetative growth rooms have many benefits for those that do not have ready access to clones. They allow you to keep genetics alive via mother plants, propagate clones and give your new plants a kick start while your primary harvest is finishing. If you plan on starting from seed every time, or have a steady supply of clones this is not necessary.

Light Blocker: The flowering room (left) will be running lights at 12/12 while the vegetative room (right) will have a longer light cycle of 18/6. To prevent light leaks you can make a light blocker using coroplast, a hot glue gun, and a small fan. Light leaks in your flower room can cause re-vegging and should be avoided at all costs.

Part List:
Black Coroplast
Hot Glue Gun
2x 120mm Box Fan

Make a maze for the air to travel through. Two 90-degree corners are enough to stop light from getting through.

How to Build a Plywood Grow Box

The Doctor’s Guide