Build an LED COB Space Bucket

A note prior to getting started:  most people that build space buckets use them to grow weed – the links I have provided to the official space bucket website showcase some pretty impressive engineering of the systems themselves but are NSFW since many build logs include pictures of weed growing, so don’t visit during work!

After discovering and browsing the r/spacebuckets subreddit and seeing all the incredible things the folks from that community have built, I was inspired to build my own pair of space buckets using the 2 LED COB grow lights I put together last week. If this post intrigues you, I recommend you check out the subreddit as well as visiting the space buckets website itself.

For those who haven’t heard the term “space bucket”, it’s essentially a mini grow box that’s built from 5 gallon pails, large plastic totes, trash cans, steel drums,  hot water tanks, or pretty much anything you have room for. Most people who build these buckets use them because of how easy it is to hide and transport them, but since I’m using mine to grow vegetables, I’m not concerned about keeping them hidden away in a closet. I’d display mine proudly in my window if they weren’t so goddamn ugly! The idea is fantastic though, because using such a small environment to grow grants you many advantages over a standard grow tent:

  • You can play with the temperature in the bucket quite easily by adjusting the speed and quantity of your fans.
  • The bucket walls are very close to your plant, and with a little treatment, can provide excellent reflection of your light source (you can also very easily add side lighting with LED strips if you need to).
  • You can build these things very cheaply.
  • They are super portable and you can move your garden around if you need to.
  • They’re fun as hell to build!

Now, not wanting to start with anything too crazy, I followed one of the basic builds from the space bucket website. Here’s what it involved:


My parts list for each bucket build is as follows:

  • 1x LED COB grow light (see build here) consisting of:
  • 2x 5 Gallon pails
  • 1x 5 Gallon pail lid
  • 1x Can of matte white spray paint (make sure it says it’ll bond to plastic)
  • 1x StarTech 80x25mm Fan
  • 1x 12V Power supply for the fans. Make sure your power supply produces enough current to power however many fans you use.
  • 1x Cheap extension cord
  • A handful of screws


The tools  I needed were:

  • Cordless drill with drill bits
  • Dremel multitool to cut plastic (a rotary tool or even a utility knife would probably do the trick)
  • Wire strippers
  • Measuring tape
  • 2 Sharpies because I guarantee you will lose one. I had to borrow a pink backup Sharpie from my wife because I was unprepared – don’t let this happen to you.


A few notes are in order before we get going.

  • Each space bucket will actually require 2x 5 gallon pails. The first bucket is cut into 2 pieces which serve as the top and bottom of the assembled unit. The second bucket is left intact and sits between the bottom and top half of the first bucket.
  • Many people cut in large intake fans on the side of the bucket for more airflow and better cooling, but I opted to skip this. My buckets are going in my chilly basement which hovers around 17-18 degrees Celsius, so I’m actually trying to keep a good amount of heat in the bucket. To promote a little airflow, I drilled a number of holes in the bottom piece of the unit.
  • Most buckets are light-proofed on the outside with black paint or black tape in order to keep them stealthy. Again, I’m not concerned with stealth, so I left them as-is. They do get pretty bright on the outside though.
  • Once complete, you have to first put your plants in containers, and then place the containers inside the space bucket. It’s best to do it this way instead of filling the space bucket itself with soil and planting inside of it.

Alright! Let’s get to it.

Creating the Bottom

First thing’s first. Grab bucket #1 and make a mark 7″ from the bottom. Mark this same measurement all the way around the bucket, then cut all the way down your line.

Measuring the space bucket bottom piece

Marking space bucket bottom piece

Cutting space bucket bottom piece

Now you’ve got your top and bottom pieces for your bucket. Let’s finish the bottom first. Take your tape, measure 3.5″ from the bottom and make a mark. Now repeat this, and make a total of 8 equidistant spots around the bottom piece. Drive a screw into each of the spots your marked, as shown. I used #8 screws about 1.25″ long.

LED COB space bucket bottom and top piece

Marking screw holes for bottom piece

Drilling in screws for bucket #2

LED COB space bucket bottom piece screws in place.

Now that the screws are in place, when you go to fit bucket #2 into the bottom piece, it will rest on the screws:

Bottom piece and bucket #2

As mentioned earlier, I wanted to keep a lot of heat in the bucket, so I didn’t use an intake fan on the side of the bucket. Instead, I drilled a small hole under each of the screws in the bottom piece for air to enter the bucket. I think the pressure created by the exhaust fan on the top will be enough to draw air up through these holes. If you’re having heat issues, you will likely need an intake fan and possibly even another exhaust fan.

Drilling airflow holes in bottom piece

Modifying Bucket #2

This is the easiest part. All you need to do to bucket #2 is remove the handle and drill a bunch of holes in the bottom of it for drainage. When your plant containers are sitting in this bucket, if you water them and it spills over, it’ll drain through these holes and into the bottom piece we just finished making.

Drilling draining holes in bucket #2

Creating the Top

Alright, this part gets a little trickier. The top piece is the part that fits into the top of bucket #2, and has a lid. This lid will contain the LED COB assembly, the fan, and the driver.

LED COB space bucket bottom, middle and top piece

The top piece fits into bucket #2.

LED COB space bucket with lid

Here is the entire assembly of the bottom piece, bucket #2, and top piece with the lid in place.

There isn’t really anything to do with the top piece, but there’s a lot of work to do on the lid. First, lay out how you want to place your components on the lid. You’ll want the light right in the center if possible.

Mocking up COB heat sink and fan

Once you have mocked up the fit for your light and fan, take your measurements and mark your cutouts. My heat sink has small clips on the side with a good amount of tension, so I decided to do a cutout just large enough to fit these clips, and pressure-fit the heat sink. It ended up fitting very snugly and securely.

Marking COB heat sink hole
LED COB assembly in place.

Top view of LED COB assembly on space bucket lid

Next, mark the spot for your fan and cut it out. I also drilled out 4 holes around the corners, in order to have something to strap cable ties to.

Cutting out fan hole

Fan hole with cable tie holes

After test-fitting the fan and light assembly, remove them and paint the inside of bucket #2, the top section, and the inside of the lid. When painting plastic, it’s a good idea to give it a little sanding to promote better adhesion.

Sanding COB Space bucket

Lightly sanded.

Painted inside of bucket white

This was after the 1st coat of matte white spray paint. I did one more coat after and it looked much more even.

When the paint’s dry, fit the fan into the cutout and fasten cable ties from the fan frame to the holes in the lid.

Attaching fan to space bucket lid

You’ll need one more hole to pass the cable through to connect from the LED driver to the LED COB under the lid.

Hold in lid for LED COB wiring

LED COB and fan on inside of space bucket lid

Looking good. Now, a few more things to add to the top of the lid. I found a spot for the LED driver and screwed it down into place. I decided that I’d use a terminal strip for the 12V connections –  this way, it’ll be easier to add additional fans or other 12V devices in the future. If you want to just splice it, that works too.

LED COB, fan, and driver on space bucket lid

Driver screwed down.

Screw terminal added to lid.

The 12V terminal strip screwed down and wired up.

With everything wired up, it was time for the moment of truth! I plugged in the driver and 12V supply, and low and behold, it lit up like the sun. The white paint does an excellent job of reflecting the light, and I’m guessing it is much easier to paint the inside than it is to line it with mylar or similar.

Build an LED COB Space Bucket

LED COB Space bucket build complete.

Bright light LED COB space bucket

After running for a couple hours, I’ve got the temperature in the bucket up to 68 degrees. I plan to run it all night and check temperature in the morning once more.

Temperature inside the bucket.


And that’s how you build an LED COB space bucket! If you’ve got a cool idea to add, I’d love to hear it – leave it in the comments below.

Now that I’ve got 2 of these buckets, each with a Vero 18 of a different color temperature, I’m going to put them head-to-head and see which color temperature is better. I have a  few different types of plants I intend to experiment with, and am curious to see how the lights do against one another over the course of the whole grow. It’ll be a 3000K vs. 5000K showdown – stay tuned!



  1. I know this might be a little off topic but you could make the bottom of it into a water reservoir and make it subirrigated, you would just have to put in a few wicking channels and put in a fill tube. It would keep you from having to keep up with watering cups and keep everything more consistant between the buckets. This page has got great info on the sub irrigated stuff if you haven’t seen it yet.

    • LEDGardener

      November 30, 2016 at 12:12 am

      That’d be nice – I’d like to automate as much as I can since I end up out of town for work often. That site looks awesome! I look forward to digging into it when I have a little time to spare.

  2. nice build! Mines the same, however I used black buckets to keep it light proof. How much light do I loose using a black bucket?

    Also regarding th eholes on the bottom. I drilled the holes, however once I set my bucket on carpet they block the intake for the most part. Could I justs use the bottom of a cut spacer, and sit the bucket inside that? Since they are the same size, it should fit and leave 1″ at the bottom?This would give it room to breathe and suck air, and be lightproof? Pretty much what you did without even drilling anything into it?

    • LEDGardener

      February 4, 2017 at 9:52 am


      If the inside of your bucket is black, you’re losing a ton of light. It’s not too difficult to make the inside reflective while keeping the outside dark – there’s a lot of info on lightproofing on the spacebuckets subreddit. A lot of guys use black duct tape and tape the shit out of the outside of the bucket to lightproof it. To lightproof intake or exhaust fans, they use dark PVC/ABS/whatever pipes with 90 degree bends in them.

      I think if I understand your question right about the holes, I have done exactly what you’re suggesting – the bottom of my bucket with holes is actually sitting inside another bucket bottom – it rests on the screws I drilled into the sides. The holes on the bottom are for drainage so when I water the plant in the bucket, the runoff drains down through those holes, into the other bucket bottom that it’s sitting in. I just drilled holes into the side of the very bottom bucket to allow a little bit of air to come in through the bottom and make its way up into the main bucket so it wasn’t totally stagnant.

      If you do the same thing, I think you’ll still need to cut a hole or drill some holes to allow the bucket to breathe. If you just sit one bucket inside another, it actually seals pretty well, and may not breathe.

      If you want a better intake, you’re better off cutting out a hole in the side of your bucket and installing a fan. Here’s a picture of my first bucket where I used an intake fan:

      I am not using one in this bucket because I’m trying to keep as much heat inside as I can, but most people probably won’t have this problem and would benefit from a fan intake.

      Sorry for the long reply – let me know if this answers your question!

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