DIY Grow Box for cold garage


My first post today. I have made a grow box that is withstanding the central northern Virginia winter pretty well in my garage. I was hoping if I post my plans and people smarter than me may see some issues I am not picking up. I have a Blueberry Auto in it now at the seedling/vegetative stage.

My Equipment:
Light: Roleadro Led Grow Full Spectrum 1000W (100W Actual) augmented with a LBW 150W (30W actual) full spectrum during vegetative stage.
Light schedule: 24/0
Temp Control: Inkbird ITC 308
Fan: Inline 195 CFM with Aurotech 4" Carbon Filter
Soil: Organic with Dr. Earth Flower Girl Soil Amendments
Pot Size: 2 Gal Fabric
Grow Space: 2’ Wide by 3’ 3 3/4"
Exhause fan runs on slowest setting unless temp rise is above 81 degrees then full speed.

I have an electrical control wired to ensure heat is good

The airflow vent are rows of 1/2" holes totaling 6 total inches along the floor hugging the outer walls covered by Landscape cloth.

I have been running this thing for 2 weeks and temperature stays in the 73 to 78 degree range even when the outside temp is below 30 in the garage.

I just want this thing to work; not to concerned with how much yield but I am open to light upgrade suggestions. I am normally an outside grower (Virginia summer weather sure causes airy buds). This is not so much a question as it is verification of concept and potential flaws. I will post pictures of the box proto type sitting in garage now.



Luon Placement Diagram


Looks like a fun project. I can’t wait to see a pic of it with a full canopy.
What’s the humidity like in the box?

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Humidity; well, whatever it is outside. I haven’t put much thought into humidity. I know that the humidity is important, but being only 2’ wide square fitting a humidifier in there will be an issue…er…maybe. I have only grown 5 plants total and all outside. In Feburary in Virginia the average relative humidity is around 75%. If that is too high; no worries the heater in there will knock that out. If too low; I may have an issue on my hands.

I didn’t want to try and fit a humidifier in my small tent either. About the same size. I hung a small damp towel to help provide humidity. My tent stays around 45 to 55% with it in there. if i don’t add the towel the humidity drops to the 20s.

But i like your design. I wanted to turn an old dresser into somthing like this. Like a hidden grow box in plain sight. Haha.

I saw something like that while searching for options on winter growing. I have built funiture before so i had a bunch of the materials laying around.

Wife didn’t trust the carbon filter and didn’t want smell in the house, so here i am trying to figure out a way for the garage.

Is the humidity really that important? If so, i shiuld probably start searching for something.

I have a full material list and cut diagrams if you want to give it a go. The 2’ floor drastically limits yeild potential.

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I would definitely like to see some plans. Just to try it and have it under my belt. Maybe make it a spot holding my seedlings and clones. Right now i have a small wooden box i put together. It works but i could upgrade.
Humidity is important. Too low and your terpenes will suffer and too high could cause mold to grow. I think it’s more important in the flowering stage though. When it’s young and in veg higher humidity is good. 60s to 70s.


welcome to the community. you’re building something awesome.


That’s pretty cool, glad it’s working out well!

Being in a cold space, RH should be easy to control for you just by adjusting the speed of your exhaust. The lights add heat, and that naturally causes RH to go down. You just have to move enough air to keep it where you want it. You might even find it’s a little dry for veg and need to add humidity.

The exhaust filter will also work in the other flow direction, so you could have all the equipment outside the box if you need more space. Reptile tank humidifiers usually have a hose if you need one of those.


When i get a moment, i will post material list, cut diagrams,cand tool list. The can be used in conjuction with the diagrams above.

Looking at small humidifiers now.

New to the forum so i am limited on replies, sorry i took so long

I haven’t seen anyone say this yet but get a small tent for your humidifier or dehumidifiers and run a 4-6 inch line from your box to the tent and use it as a lung room

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Materials List (Box only does not include electronics):

1- 1x4 6 feet long
7- 1x4 8 feet long
2- 8’x4’x2" Polystyrene foam insulating with Foil
2- 8’x4’x1/4" Luon, OSB, or Plywood
1- Tube Liquid Nails
2- Door Hinges
2- Spring Loaded Toggle Latches
1- Handle (Cabinet pull, gate handle, etc)
Nails 3/4" Finish Nails, Brads 3/4", Staples 3/4", Wood Screws 3/4" (All work depending on how you want to attach and tools available).
Landscape cloth
Foil Tape

Tools Required
Square Edge (For saw guide) over 8’ Long
Hand Saw and Circular Saw
Caulk Gun
Screw Driver
Tape Measure

Tools Suggested:
Drywall T-Square
Mitre/Chop Saw
Kreig Jig with 1 1/4" Screws
Brad or Staple nailer
Speed Square
Impact screw gun
Table Saw
Hole Saw (Sized for your exhaust fan)
Drill bit for your intake vents (May be the Hole Saw)

My Electronics List:
Amazon Basic Space Heater 500W
Tripole USB Desk Fan
InkBird ITC308
Outlets for equipment
2 Single Pole Switches
1 KB Electronics 811006 2.5Amp 120V Fan Speed Controller
Zettler Power Relay SPDT 30A 120V Relay with 120V control Coil
Roleadro LED Grow Light Full Spectrum 1000W
LBW 150W LED Full Spectrum Light
Aopin KSD301 NC 40 Degrees Celsius 10A “Clicks On” Safety Switch (Turns off when Temperature reaches 40 Degrees Celsius as a safety if Heater control fails)


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The below diagrams and cutting sheets will build an insulated box with a 3/4" airgap between sheeting and insulation adding to the R-value. The box will be 30" Wide and 4’ 3 1/2" tall outer dimensions. Depending on material used for sheeting; the box can be painted or stained to add to a stealth grow situation.

Luon Cut Diagram

Luon Placement Diagram

Just follow the cut sheets color and build by the diagram colors. I suggested the frame be assembled with a Kreig Jig, but pre drilling and using 1 1/4" wood screws would work. Nailing will work as well but you would need at least 1 1/4" nails. The foam boards will be glued to the frame with the liquid nails and seams covered with foil tape. The Sheeting will be attached with Brads or staples no longer that 3/4". Wood screws or finish nails will work as well. Ensure the hinges are attached to the frame of the box and the door.


That’s a sweet setup! Nice job! I would imagine humidity won’t be much of an issue the more you have to water. You can use a small Tupperware with water and a rag to wick the moisture for the space you have.


Thats a sweet set up. @ConcreteBudz also did a stealth box and produced some great girls

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Sweeet set up design brother!!! Heres my Stealth Box i can tag you in both my journals so you can peep them if you woulr like. Your gonna kill it!!


Btw welcome to the community!