DIY Grow Box




Introduction: DIY Grow Box

Prompted by my daughters middle school project, might as well try to build a mini grow box. I have seen similar kits for hundreds of dollars online so how cheap could I make it and for it to do about the same thing.

As the first attempt, some corners were cut and I think now I would use LED red/blue lights instead of the HE lights I happen to have had around the house. The lights I used did fit into an acceptable light spectrum and only used a total of 45w when on but working out the kinks on that part now.

Total cost was minimal as the most expensive single part was the cooling fans and thermostat and I think I got them on sale for about $35. The rest for the most part was salvaged parts from prior projects around the house. However, if bought new I would estimate about $50 total cost.

Step 1: Materials

Materials will depend on what size you want the box to be. In this case, the box was 33" tall x 18.5" wide x 18" deep to house starter plants and those that will reach a max height of about 24". Of course, if you wish to build bigger, add to the below supplies. No special tools needed, just a drill, circular saw, knife, square, and a tape measure. A multi-meter would be helpful if your kind of new to electrical stuff.

Common 1/4 plywood (1 x sheet)

Cooling fans (x2)

Thermostat & Speed Controller (1)

about 8' of 1" x 2" for the basic frame

Hinges (2)

Wood Screws .25" (6) for Hinges

Wood Screws 1" estimate (30)

Underfloor Heating Foil / Foil Tape / Simply Aluminum Foil

1-1.25" Deep Handy Utility Box (3)

24" Red 14 Guage electrical Wire

24" Black 14 Guage Electrical Wire

24" Green/White 14 Guage Electrical Wire

Wire nuts, a couple

Electrical Wire 3 prong (I used one from an old appliance I had but I am sure Lowes has them cheap)

1" x 2" x 6' (1) not needed but I did use it to cover seams between cuts like on top and above the door


Electrical outlet (1)

Light switch (1)

Plus and minus using basic creativity.

Step 2: Step Two: Frame It Out

I did not take pictures along the way but I think it is easy enough to figure this one out.

Depening on how big you want it, frame out a cube basically. I braced up the corners to prevent any swaying when moving.

The top back of the box I framed out the part that will hold the electrical switches and sealed it away from the grow area below.

Step 3: Step Three: Add the Sides, Door, Top and Bottom.

I simply measured what was needed and cut. I screwed on the left, right, back, and bottom.

The front contained the door so one single cut along the top, added the hinges, and door done.

The top has two removable parts, one allowing a viewing area and light adjustment in the front and the other access to the power switches.

Step 4: Step Four: Reflective Material

Using whatever you determine is best or you happen to have around the house, now is a good time to add it. I used some Underfloor Heating Foil I had and applied it everywhere I could to contain heat, reflect light, and seal up the inside of the box from moisture. Eventually I ran out and used Aluminum Foil for the inside of the door.

Step 5: Step Five: Fans Holes

For the fans, I used some common fans used in entertainment centers to keep ones X-Box and such cool. I bought a kit with two fans and one thermostat that I could program to come on and shut off at predetermined temperatures. The particular kit I used was simply a plug and play using a USB with no wiring required but I did find out the wires ran a little short thus some wires are seen inside of the box when my original plan was to run all wires on the outside.

Simple enough, how ever big the fans are make a round hole on the bottom back corner of one side about 6" from the bottom to serve as the cool air intake. Create the second hole in the opposite side in the top front of the box to serve as the warm air exhaust.

Step 6: Step Six: Sand/Stain

Of course you can do this when ever you wish but now prior to putting wires in and your fans, it may make better sense to sand and stain now. I was not going for looks here as you may see but I do think some water resistance would be a good idea.

Step 7: Step Seven: Electrical

Actually, this was not as hard as some may think.

Fans: Install the fans, intake fan on the bottom should be facing in allowing it to suck in outside air and push it into the box. Exhaust fan should be facing out pulling air out of the box.

Box 1, Light Switch: In this project I used the light switch as the master control for the whole unit.

Box 2, Junction Box and Power Supply: All wires centralized here and this is where I hooked up the power cable.

Box 3, Outlet: Simple enough, a power outlet for my Thermostat and an extra outlet for a secondary light or whatever.

I will not give detailed instructions on how to wire things because I am not a electrician and I do not want to give bad advice and someone shock themselves but youtube is a great resource for this one.

Temperature Probe: With the thermostat there is a small probe connected to it. I drilled a small hole in the floor of the electrical box and inserted the probe. You can adjust where the probe rest in the box by tiring it off in the electrical box.

Lights: I drilled a small hole in the front of the box to allow the power supply for the lights to come out at the highest point so I can adjust them up and down accordingly. In this case, I used two lag bolts to tie off the power supply for the lights to adjust their height. I used a three outlet light socket for three HE lights that use about 45w of power well below the estimated max of the box. Again, LED grow lights are a little costly but I think worth the price given the reward and they burn a little cooler if heat becomes a problem.

Settings: Once you figure out the plant you want to put in there and required temperature ranges, program the thermostat and you are all done.

Step 8: Step Eight: Final Touches and Grow

Door Lock: I found a little hook and made it work as in the picture.


Plants, so far this seems to work best for already developed small plants and lighting seems to be responsible for 99% of my problems with plants getting leggy.

I have had no problems with being too hot or too cool. The lights warm the box up and once they hit my programed temperature, the fans kick on blow some cool air, move the plants around a little and about a minute later the fans cut off.

I have had issues with drying out. I have found the fans pick up the water and take it away so this system will likely be best with some type of drip irrigation system, frequent checks (daily or every other day), or hydroponic system. In the near future I am gong to insert LED lights and use a homemade hydro system and test that out.

Indoor Gardening Contest 2016

Runner Up in the
Indoor Gardening Contest 2016

First Time Authors Contest 2016

Participated in the
First Time Authors Contest 2016

Make it Glow Contest 2016

Participated in the
Make it Glow Contest 2016

1 Person Made This Project!


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5 years ago

Nice Job!

Regarding an irrigation system, I recommend one without a pump to minimize possible failure, they work just by the pressure of the water column of the tank or by osmotic compensation.

Like this ones:

Another thing that you should think about, when it comes to lighting plants up with LED, is that you have a loss of heat if you use LEDs instead of conventional lamps like High Pressure Sodium or HE lamps like you used. The heat radiation of conventional lamps seems to be wasted energy but the plants need the heat to perform photosynthesis optimally. In a well circulated room you get a good temperature difference between day and night in your box! With LEDs you maybe have to heat the thing up and this is much more energy costing in the end.... Only if you have an automatic climate system or a perfect climate anyway I would recommend using LEDs....

I worked some years for a horticulture company where I sold boxes like this, but until now they still use HPS light and no LEDs....

But opinions tend to defer....


Reply 1 year ago

I know this is old but thank you or the tips.


Reply 5 years ago

and I know HPS lamps would be way to hot in your case but if you had a good climatic condition with your HE lamp, I would recommend to keep them!


1 year ago

I realize this is a old thread...I am Old
Where did you get your Thermostat/Fan controller that is shown as a blue back screen.
Also I have a Grobo downstairs for my medical marijuana. (Canada) that I grow a high content strain of CBD for pain.
To reduce the smell of fresh flowers, veggies..ect. I added a dryer vent kit and a extra small PC fan to take the smell of growing exhausting outside.
But I am interested in your controller


Reply 1 year ago

So, I hope to be joining you on the same grow for the same reason one day. Anyway, I found this one on amazon (link below). I like the idea of the vent kit. One thing I did learn, the next one will be bigger and I would add a device to maintain moisture in the air. Totally forgot about it. The controller was hard to find as I was not sure what I was looking for at first. Also, the next build I think I will use different materials, to make it a little lighter. For the most part I used a lot of stuff that I had available.


5 years ago

Thanks, seems the only issue I have run into is lighting and water. I think LED Red/Blue will work much better and I may make a small drip irrigation system to keep the plants moist, the fans move them around and push air in and out but takes all the moisture with it.


5 years ago

looks good. I made something similar, first just from a cardboard box, but later by just gluing polystyrene plates together.Used ordinary wood/paper glue. worked perfectly. Cheaper than wood, easy to process and keeps the heat in