If you’re going to the trouble of building your own grow light system, you might as well put all those lazy photons you’re producing to work. It’s amazing how much light and growing potential is wasted if you’re simply running your lights in open air. I took a rather unscientific measurement of how much light was hitting my plant shelf before creating the DIY grow tent and after, and the difference was huge.
Edit 06-18-2017: Here’s another tent I built using the same black and white poly, this time paired with some spare wood I had lying around.
Advantages of Using a Grow Tent
There are a few reasons why using a grow tent is a good idea:
- You can control the temperature of your growing area better
- You can control the humidity of your growing area better
- A tent with reflective walls will redirect a TON of light back towards your plants that would otherwise have been lost. With no reflective film and just a regular old wire shelf, I was getting about 6700 Lux (Lumens per square meter).
In the same position, at the same distance from the lights, but with the reflective lining in place, this measurement increased to 24,000+ Lux.
Now, worth noting is the fact that Lumens, Lux, or Footcandles are not good units of measurement for horticultural lighting, as they’re biased towards the yellow and green range of light, which humans perceive strongest.
A better indicator for plants is a measurement of PPFD (Photosynthetically-active Photon Flux Density), which is measured in umol/second/meter squared. PPFD is tailored toward light that plants can use (hence the “photosynthetically active” part of the name), but a meter to measure PPFD is pretty expensive, and I figured measuring Lux still gives a general idea of how big a difference the tent makes.
Now, that’s all fine and dandy, but pre-fabbed grow tents can be very expensive. Luckily, a DIY grow tent can be built relatively cheap, and here’s how:
Here’s what you’re going to need to build your DIY grow tent:
- An adjustable rack to hold your lights and plants like this one: AmazonBasics 5-Shelf Shelving Unit – Black
- A good quality, strong tape like this: Gorilla Glue 6003001 Tough & Wide Tape
- Black and white poly. The white side reflects light and the black side absorbs it, so it’s contained within the tent. Here’s the one I used: Black & White Poly
- Some Velcro or cable ties to manage your wiring
I built my little tent with the goal of making it as easy as possible. Here’s how I did it:
1. Assemble your rack. Use however many shelves you think you’ll need. For my rack, I’m going to start with all 4 of my lights on one shelf while the seedlings are small. Once the plants take up more room, I’ll move 2 of my lights down to the bottom shelf, and split the plants up between their original shelf and the new spot on the ground.
2. Make modifications for your lights, if necessary. In order to accommodate my lights, I cut out parts of the shelves to allow the light to sit flat on them:
3. Run your wiring to your lights (see this post for help wiring your LEDs!). I snaked my wiring through the “V’s” of the shelves in order to keep it in place without needing to worry about strapping it to the shelf. Along the sides, I used Velcro to fasten the wire to the post:
4. Position the poly. Unfold your black and white poly and drape it over the rack. This can be a pain in the ass to do by yourself. I was working with a 10’x10′ sheet, so it was fairly manageable, but this stuff comes in much bigger pieces. You may need to cut it to a workable size if you’re working with a larger sheet.
In order to reduce waste, you’re going to want to align 2 edges of the poly with 2 edges of the rack – the top and one of the sides. Position the poly so one of its edges runs along the top shelf. You should have a whole pile of slack hanging at the bottom of the rack (see below pic). Once you have the top of the rack covered and lined up nicely, shift the poly over so that there’s just enough of it to wrap around one side and meet up with one of the front posts.
In my pic below, I have aligned the poly edge with the top and with the front right post (notice how much slack remains on the left side – this will be cut off and used as my door).
5. Tape the poly to the top shelf. First, tape the edge of the poly to the front of the top shelf. Once the poly is taped to the top shelf, take that slack at the bottom, and pull it under the 4 feet of the shelf, so the bottom is wrapped too.
6. Cut and fasten the sides. Pull the poly tight so it wraps around the back and both sides of the rack, leaving the front as the only thing that’s not covered. Take a strip of tape and fasten your poly to the side post that you lined up with in Step 5. Now, with the top and one side taped, cut the excess material off of your remaining side and then tape it to its front post as well. You will have to do some Christmas-present-style wrapping of the corners where the top and bottom meet the sides – I won’t judge you if this part doesn’t look pretty; mine was atrocious.
7. Trim the bottom. Get rid of the excess that comes out from beneath the rack. I trimmed mine flush with the side posts.
8. Make your door using the excess you cut off from the side. If you’re using a 10’x10′ sheet like me, you should have enough excess poly to make a door. Take your excess piece and drape it over the top of the rack. If it hangs way over, it’s fine. Once its hanging, you can judge how much you’ll need to cut off it to make it fit nicely. I didn’t need to take much off – you’ll need it to be wider than the sides of your rack for it to close properly. Tape the top and back of the door down, and leave the front unsecured.
9. Seal the door when it’s closed. To do this, I’ve just used a few pieces of tape along the 2 sides of the door to hold it closed. You could use magnets if you’re fancy.
10. Turn on your lights and check the temperature and humidity of your tent. Run your lights for a typical cycle and monitor the conditions. My basement is cold, so I intend to keep things fairly sealed up in order to heat the inside of the tent with the heat generated from the lights. If you find you have too much heat, cut in some venting at the top of the enclosure to allow heat to escape.
Consider running a fan at the bottom to circulate air up and through the vents (fans are always a good idea anyway, in order to move air and make the seedlings stronger). If your humidity is low, you can set up a humidifier on a timer, or use a model that will run until it hits a set humidity, then shut off.
And that’s it! for under a hundred buckaroos, you’ve got a sweet tent that will really increase your light and your control over growing conditions. If you’ve got any cool ideas to improve on this, let me know in the comments below.