DIY Grow Box Build

Cabinet-style Grow Box

Our older grow setups have been the classic blacked-out tents with mylar interiors, but we found that while they work quite well, they don’t blend well into living spaces and can be overbearing in a bedroom. So we decided to put together this cabinet style wood grow box to fit better in our place.

This isn’t necessarily the best setup for everyone and there is room for improvements, but this is to document our process so you can use or modify any of the details.

Size
This box is 48 inches wide, 24 inches tall, and 16 inches deep, standing on four wheels for a final height of about 30 inches. It was meant to resemble a dresser or cabinet to hide in plain sight!

Cost
While these boxes are pretty lightweight and sturdy, they’re not that much cheaper than a grow box, coming to around $200-$300, but the improvement in our living space was worth the difference.
Duct fans: $80
Wood: $100
Hinges: $15
Wheels: $45
Vent covers: $30
(Prices in USD)

Time
This build from design to box probably took us a 3-4 days. Big stores like home depot or local wood shops will cut the wood for you for free if you don’t have the tools to do so yourself.

Grow Box Design

We wanted something low-key that we’d be comfortable keeping in a place that we spend a lot of time. A few key aspects we wanted to optimize were light quality, darkness at night, good air circulation and interior air agitation. This box fits a 4 foot LED light bar but can be swapped out with other LEDs or fluorescent bulbs. Some of the requirements below:

Strength
The long horizontal beams attach to the length of the board and the pillar at the centre, locking everything in place. There isn’t much racking, twisting, or bending with this frame installed because the doors don’t need to bear load. The doors are inset though, so once closed they help with solidifying the structure.

Mobility
We added wheels so that the box would be easily moveable as our last ones were completely immobile without them, which made for a lot more difficulty cleaning, rearranging or moving. The box is lightweight and with a powerbar and single extension cord the whole setup can be moved across the room without issue. 

Discrete
Since this is a bonsai box, we went with a relatively short height and a wide profile. The 1:2 dimension and maple exterior helps give the impression of furniture, and most people don’t even notice the box. If you’re going for a more yield oriented grow, another size up could be 48″x36″x24″.

Leak-proof
Because getting the interior truly dark is necessary for flowering, the curved elbow vents at the back point downward and change angle to reduce the amount of light coming into the box. Further, caulking the interior of the box will help with leaks, and if necessary you can throw a sheet or blanket over the box to eliminate all possible leakage. Foam window lining will help seal leaks along the doors.

The Light

Since we wanted a low and wide grow box that feels a bit like furniture, we swapped out our OpticLED CREE COBs for an LED bar light by HLG because the long strip of LEDs diffuses light better for a wide shape than a large single LED like the Optic.  

The HLGs are on the pricier side of LED lights but the build quality is great and the lights have a highly tuned spectrum. That said, there are a ton of LEDs, from strips to bars, that are economical alternatives. There’s also the option of using the slightly more cumbersome and fragile fluorescent bulbs as the format fits the box well. 

We bought ours ‘DIY’ so it didn’t come with a driver, meaning we had to wire the light to the driver and that to the power cable, but there are HLGs that come prewired which is probably worth the search. Shoutout to LED Grow Lights Depot for all the help answering our questions!

So far the light is great: it doesn’t get too hot and the plants seem to love the light quality.

What You’ll Need:

In terms of the materials we used to build this grow box, you can swap materials out to your preference. Oak, white maple, OSB particleboard are all great alternatives with different hardnesses. Most of these can be found at a hardware store except for the LED lights and of course the plants (unless you’ve got a really good hardware store lol).

Step 1: Create base with floor and sides

Screw sides into the floor board, inset 1/4″ from the back side and 1/2″ from the front

Step 2: Install back board

Screw 1/4″ board onto the back of the side boards and then up through the bottom of the base

Optional: Cut the 4″ ventilation holes into back board first

Step 3: Install top board

Screw the top board down onto the side and back boards every 6-10 inches or so

Step 4: Install braces for the box

Screw in the vertical beam from the top and bottom after insetting it by 1/2″ from the front edge.

Then place the 47″ horizontal beams behind this column and screw them into place. These stabilize the box, preventing racking or flexing, so it’s not a bad idea if you want to choose a stronger wood for these such as Oak. These also block some light and serve as a good place to set the window-sealing foam.

Step 5: Add hinges

Place the doors in their final position and tape them down with masking tape – in order to rest the hinges against the door and the box sides they’ll have to be secured in place. You can put one door in and fully screw the hinges before dropping in the second.

Step 6: Install wheels

You can install four wheels onto the corners of the base. In the case of a heavy grow or a larger box, you can add a 5th or 6th under the centre of the box.

Step 7: Install fans

Drill out the 4-inch holes a few inches from the corners if you haven’t already and insert the fans so that one draws fresh air in and the other pulls air out from the other side. Our fans are 14 watt 100 CFM by Vivosun but any 4″ duct fan will do!

Step 8: Add elbow pipes

Slide the elbow pipes over the fan extending out of the back of the box to avoid dust and light leaks. Duct tubing would also work as an alternative. You can add a simple layer of filter floss often used in aquarium filters, or a screen, to cover the intake and prevent hairs and larger particles from entering the box.

Step 9: Add interior fans

Add screw hooks to the ceiling to hang interior air circulators or agitators to ensure good airflow within the box and airflow over most of the canopy. The airflow can be moderated/modified depending on how humid the box is and how many plants you’ve got in there.

Step 10: Install light and finishing touches

Finally you can finish up by adding your light, caulking the joints, and wiring everything up to a power bar on the back. We suggest keeping much of the electrical work outside of the grow box to prevent water or humidity from getting into the wiring. You can tarp the interior for better waterproofing as well.

Light Leaks

Black caulking along the interior edges will block light and prevent water leaks. Window sealing foam strips are helpful for sealing the doors and if necessary, you can throw a sheet or blanket over it to remove any remaining light.

You can use a camera with a timer to photograph a long exposure inside. This will help identify areas that are leaking light, how much, and where to improve. Once you’re working on the improvements, whether the elbow joints, caulking or a cover, you can test each step to see when you’re done. A well sealed box won’t show light on a 30 second exposure (with ISO 400 in our tests).

Air Filtration

Aquarium filter floss is a cheap and easy material you can use to tape over the intake vent and even the interior agitators to keep out hairs and debris from the box (extra helpful for pet owners lol). Once you’ve got a few plants in there, make sure to install your humidity/temperature reader and keep an eye on the levels, adjusting from there.

Finishings

Box with beam, corner exterior and interior.

Install column and then add the beams and doors.

Caulk each crack with opaque black window caulking to seal out light and water, and then you can then paint the interior afterward.

To power the box without filling the inside with wires, we cut out a small notch for the fan’s power wire to sit as it weaves back out from underneath. You can drill a hole first and saw down to create this shape beneath the fan holes depending on how many wire’s you’ve got.

After running the cord through its notch and fitting the fan in place, you can use this type of sealing tack to close out any light leaks or gaps.

On the other side we’ve got our lighting and interior fans so we drilled out a few extra holes. One of the holes was filled with tack in case we need to add any other power later on. You can mount your powerbar between the two fan exhausts at the back of the box to keep the electricals outside of the box but also still out of sight.

This is just the guide for how we did it so if it doesn’t fit your needs you can adjust these designs – we’re interested in updating and improving these pages so if you do build a box, send us some pics we can add to the page!

We mounted the driver off the wall to help it stay cool and avoid any heat buildup, mounting it off the wall by half an inch to keep it out of reach of water or spray and give as much room as possible to the plants.

Left: Completed box, off, at night. Right: Box, on, during the day. 

Note the small gap in bottom of door leaking light. Next steps are adding light-blocking foam strips to the doors to close those off, after redoing the hinges to tighten up that gap.

 Here we have the hardware (light, driver, fans) built in toward the top of the box to stay out of the way. Air is drawn in on the left and drawn out of the exhaust on the right. It still needs internal circulation/agitation so we have to add two 4 inch fans inside, pointed downward 45 degrees in the direction of the overall flow of the box.

We’re by no means carpenters and don’t have a ton of experience with this sort of thing, but this was the build we put together and we wanted to share the design, plans, our thoughts and some phone pics we took along the way. 

It’s quiet, windy, bright and best of all it’s discrete. Sometimes we use it as a desk and can’t really tell when it’s on or off which is a huge plus, and people don’t usually notice them especially during the daytime!

We’re always looking for suggestions and improvements so let us know if you have any ideas to add or if you embark on making a box like this send us pics!