Small Indoor LED Plant Grow Room





Introduction: Small Indoor LED Plant Grow Room

I have done a few indoor gardens before, mostly because the weather in Michigan does not allow for a very long season. I recently moved to Phoenix and tried container gardening outside and was disappointed in the amount of pests that decimated my small container farm. So here is my take on a very small indoor LED garden to see how it works out.

Step 1: Parts & Tools


  • Cardboard Box
  • LED Light
  • Aluminum Foil
  • Spray Adhesive


  • Box Cutter
  • Scissors

Step 2: Line With Reflective Surface

I chose to line the box with aluminum foil because it is highly reflective and can act as a water barrier. I overlapped all the corners so that if water does spill in the box it won't ruin it. The spray adhesive is easy to apply and sticks strongly to the box.

Step 3: Cut Out Light Hole

Cut out a hole that will allow the light you have penetrate into the box.

I am using a light that I created in another project to shine into the box. It just sits on top of the box and has a fantastic coverage. The heat created by the lights can radiate up and you can easily lift up to check on your plants.

Since my light covers almost the entire top of the box I cut a hole in the entire top except for the side with a flap (left an inch or so) and the corners to keep some strength in the box.

Step 4: Add Plants, Fertilize, Grow

I started some seedlings in a small starter tray then transferred the plants to small pots. I also used the flap that I cut out as a lifter to get the plants closer to the light before they mature.

I use a hydroponic fertilizer to keep the plants growing strong. This is essentially the same thing as doing a hydroponic setup but using a sterile grow medium that looks like soil. I water every day based on the provided feeding schedule.



    • Pets Challenge

      Pets Challenge
    • Woodworking Contest

      Woodworking Contest
    • Colors of the Rainbow Contest

      Colors of the Rainbow Contest

    We have a be nice policy.
    Please be positive and constructive.




    Hi. I'm planning on building a growbox for my chilli plants and for lettuce. I've been looking at both your design and one by OKGrowin which uses much stronger lights.

    OKGrowin suggests that LED strip lights might be too lacking in penetrative power. Is this something you have found?

    How hot does the heatsink get? Can you comfortably put your hand on it? Also, how much power does the whole thing use? You've got about 3m of LED strip, right? How large is the cardboard box? Do you think it is too much, not enough? Is there anything you would consider changing if you started this project again?

    Sorry if I have missed the answers to these Qs in the text somewhere.

    6 replies

    I honestly don't understand why people go through the effort to DIY LED lights, EXCEPT if someone would have custom requirements for LEDs. Because 300W LED lights you can get for $65 shipped if you look on ebay. I am currently growing Chillies with two of such lights. And those 300W lights have red/blue and a bunch of whites. Nothing "fancy", but's just a grow light, not rocket science.

    GeorgR, People that use this site like to DIY things. I am sorry you like to just buy everything but that is not what the community at instructables is about. I also like to do very simple projects with a very little budget. $65 is not anywhere close to the $25 light I created that happens to also be useful for other things in my life. That is why I DIY. It may not seem like a difference to you but it is to me. If you don't have constructive criticism to share please keep it to yourself.

    If you are worried about not being enough light try these out. They are brighter than the ones I am using and have a built in aluminum backing which is more effective at dissipating heat.

    I have been growing herbs just fine with about 8m of 5050 style strip lights in a 14"x14" box. The heat generated by these lights is negligible, especially when hooked up to a voltage regulator (45'C). I can touch the aluminum mount easily with no worries. Without the regulator they get a little toasty (52'C).

    If I were to do this again I would use a mix of warm and cool white 7020 on aluminum to add a larger growing spectrum and better heat dissipation. I have been pleased with the growing results but have heard this can bump growth even more.


    Sorry to bother you again. Are you using a different power supply to when you used the lights for the seedlings? I'm not an expert (barely a beginner) but the one you linked to maxes out at 72W and 8m of lights (5050 or 5630?) goes beyond that.

    Yes, used the same 6A 72W power supply. If you want to use 6530 you could get a larger power supply but you are getting more light and could probably use less lights. In general I have found that these cheap strip lights draw less power than they claim so you should be fine.

    Thanks for your reply. I was also planning on using a mixture of cool and warm whites - possibly set up so that I can adjust the ratio as I go along. My budget is fairly low, and I don't want to make too much of a dent in the monthly electricity costs.

    I saw the 7020s mentioned in the comments, but I haven't been able to find much information to compare them with the 5630 flexible strips I was looking into before.

    Just to add to the discussion: in professional greenhouses the ratio blue/red is 2/1 or 3/1 There is also an interesting effect of far-red (730-740nm) which gives you longer internodes on a couple of varieties. The interesting thing is that you only need 10-20 minutes of far-red at the end of the day (google EOD LED) followed by a couple of minutes of red (660nm) to give you the longer internodes.

    Here is a side by side comparison of seedlings from the same initial tray. Same fertilizer and water schedule, different lighting (14hrs of LED) and environment (February in Phoenix, AZ, USA ~ 12.5 hrs of sunlight).


    Your design is so simple that I didnt even think of it myself. I was struggling with wood and polyurethane plates till I saw yrs and thought "yeah".
    Fairness bids though to say my plans were for something i could also use outside, but for now I just settle for the carton.
    I have a 5 watt growlamp (LED) in it and though that might not be enough to let the plants go to full development, but quite enough to rear seeds till I can put them outside.

    A quick update, two weeks after transplanting I was able to harvest lettuce and basil for dinner. (two weeks to grow the seedlings in the starter tray from seed)

    2 replies

    That's great to hear, plants look really nice.

    What type of basil and lettuce are you growing?

    Sweet Italian Basil, and Black Seeded Simpson Lettuce

    I've used both red/blue combination and white LED's for growing lettuce and tomatoes, found little if any difference. White off the shelf LED bulbs are easier to find, and wattage wise are comparable.

    As to the comments about plants doing bast with red and blue LEDs. I have found that is true for some plants others that is not true. I have several orchids that haven't done well due to insufficient natural light (my windows are shredded to much). Several haven't bloomed in years. I built a grow lamp using red and blue LEDs. The orchids had great root growth but little to no leaf growth.

    I tried some old incandescent lights i had and got results that were a bit better. So I built a new grow lamp using 2700K white LED and supplemented with 660 red and 465 blue (one blue and red for every 4 strips of white). three A couple of months after building the lamp 3 orchids sent out flower shoots. Two of those hadn't bloomed in at least 4 years. In contrast some snapdragon and columbine plants have done very well under the red and blue grow lamp. The power consumption of the white LED lamp is about the same as the red and blue lamp.

    I have read about a experimental green house that was made with transparent solar panels that absorbed mostly green and yellow light while allowing red and blue to pass through and reach the plants. The idea was to make a green house that generated power as well as food. Many of the plants did well but some didn't. Many plants have pigments to guide growth. Some pigments are not strictly sensitive to red and blue. I suspect that pigments other than chlorophyll are why some plants don't do very well under red and blue grow lamps.

    1 reply

    I think for people interested in blooming Red/Blue supplemental lights are helpful. Since I am growing Lettuce and herbs that I do not want to bloom, not having intense red/blue light is helpful in keeping them from blooming.

    Very nice project!
    You kept it simple, quick and easy!
    But the LEDs you have taken are really inefficient for plant growing, Photosynthesis has its peaks by royal blue (~480nm) and deep red(~650nm) light, the benefit of using an LED grow light is that you can buy LEDs in exact these wavelengths, to provide the most efficient grow...
    keep on building!

    2 replies

    Yes, I am aware that many are experimenting with Red/Blue combination setups. To date I have remained skeptical of the actual growth output of these DIY Red/Blue setups using cheap components. I know $2k+ setups seem to have nailed it but it is not economical for a home grower to use them at this time. This 5000k light puts out more light per watt than a CFL setup and it is much cheaper to build. Oh, and you don't need special glasses to check your plants.

    The assumption that red + blue LEDs will be better has been around for a considerable time. I previously built quite a large two-level hydroponic grow pod with about 350W of red and blue LEDs that were cooled by the hydroponic fluid.

    Then I decided to do more research because it was quite clear that total light output from white LEDs is much much higher than monochrome LEDs. It's true that there are peaks in photosythesis activity at red and blue but it's not a case of the rest of light, even green, from going to waste. So I rebuilt the rig with around 220W of a combination of warm and cool LEDs. Nutrient uptake (and hence growth) was around 10% higher. These results are in line with some others also. Essentially white LEDs are *much* better for growing plants.