Introduction: $78 Grow Light - Full-Spectrum, 22 Watts, No Heat

Picture of $78 Grow Light - Full-Spectrum, 22 Watts, No Heat

Growing plants indoors enables a level of precision not available outdoors. For this reason, it's well-suited to growing a wide variety of crops and making data driven decisions on yield, timeframes, energy consumption, etc. A current project involves producing food under a queen bed lofted five feet up (this creates 167 cubic feet of space). Inside of a grow tent, I’m first adding trays of produce. This requires sufficient quantity and quality of light for optimal production.

Most grow lights are very expensive, energy hogs, and emit an insane amount of heat. This heat requires more energy for intake and exhaust fans to keep an ideal ambient temperature for the plants. Although LED lights emit only 60 lumens per watt consumed, half of High Pressure Sodium lights at 120 lm/W, the low cost and long lifespan of LEDs make them much more efficient.

This DIY version consumes less than 22 watts of energy (half as much as a laptop) and can be run for less than $12/year*. The lights are barely warmer than ambient temperature, eliminating the need for massive input and output fans . This light uses easily accessible materials, takes about 15 minutes to build, is lightweight, durable, radiates practically no heat and is very inexpensive.

*22 Watts × 8765 hours (one year) = 193 kWh (kWh = W × hr / 1000). US Average Price of 12 cents/kilowatt-hour as of May, 2015. 193 kWh * $0.12 = $23.16/year. If you run the lights 12 hours/day, this is $11.58 annually or less than a dollar a month.

Step 1: Gather Materials

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Hot glue, drill, metal snips, old extension cord - not included in price

Baking Pans - $1/each

E27 Socket (This is the most common size of sockets on the Edison Scale that runs from 4-40) - $1/each

Plug - used old extension cord Wiring - $0.25

Ikea Dioder - $20

***TaoTronics 3 Band LED Grow Light - $27/each.

Total Cost: $78.25

***430, 460, 630 and 660 are 4 peaks wavelength of growth spectrum for maximum ChlorophyII A and B production.

Blue 400~470 nanometers light is good for photosynthesis; and helps induce Chlorophyll and Carotenoid. Blue light is best for healthy leaves.

Red 610 ~ 720 nanometers light (660 nanometers is the peak wavelength) for photosynthesis and photoperiodism. Red light is best for blooming and fruits.

Step 2: Cut and Drill Holes in Both Baking Pans

Picture of Cut and Drill Holes in Both Baking Pans

Cut holes in two baking pans. The top pan should allow the bulb to pass all the way through up to the rim. The bottom pan should allow the bulb to rest on top while not blocking any of the lights from shining out.

Trace around the lights for the top pan. Place on top of bottom pan and trace another circle with a diameter a half inch shorter.

Drill holes that allow the cords to pass through to power the LED strips.

Step 3: Hot Glue!

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Hot glue the top pan onto the bottom pan, sandwiching the bulbs in between.

Step 4: More Hot Glue!

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Hot glue LED strips onto bottom of glued unit. Thread wires through the holes and connect power to led strips.

Step 5: Attach Wiring

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If necessary, wire together the two lights in parallel and the power cord to either one.

Step 6: Grow!

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I’ll have more data in the next instructable on which plants perform best when factoring yield, market price and maintenance. I’ll also show how to create an easy frame (just pvc and hot glue) for multiple lights and plants. Finally, I’ll be testing soil vs. hydroponics vs. aeroponics.

Please favorite above and comment below!


user4556 (author)2016-05-30

Hi Martin,

Thanks very much for sharing this project. Apologies for my ignorance I am quite new to electric wiring but could you tell me what are the green lid kind in step-5 photo ?

Ultimate Warrior (author)2015-07-14

What are the Ikea strips for? What wavelength are they emmiting?

godsdog69 (author)2015-05-17

Just passing thru interesting project ....found this dont know if it's the same

amclaussen (author)2015-05-13

Another quick thought: Most LEDs produce light that is composed of narrow peak wavelenghts, thus, it has a discontinuous spectrum. On the other side, so called "full spectrum" fluorescent, high color quality lights, while not truly "continuous spectrum" have a much better light production across the visible and near UV wavelenghts. It is posible that plants respond better to such wide spectrum light instead of the very narrow peaked light the LEDs put out.

My sister has had a long history with "SAD" (Seasonal Affective Disorder), a kind of disorder that is aggravated when the patient passes seasonally through long months with fewer sunlight hours, and discovered that very modern LED lights do not help her at all, but quite the contrary. But high quality fluorescent lights (of the type used to work with paint mixing and color matching at night) truly helped her mood. FWIW.

Xonk61 (author)amclaussen2015-05-16

a simple means to see what spectrum profile your lights have would be to reflect the light at an angle off of a CD into your eye, and you will see the brightest colors which are split apart by the "grooves" on the CD. Full Spectrum light will have a fairly even transition through the spectrum, whereas an RGB source will show specific spectra of the primary colors, with perhaps a little blending between the "peaks"

amclaussen (author)Xonk612015-05-16

Very clever! (using s CD to check spectrum...) Thanks for this info Xonk61, never though of that. That way, one can quickly check if a given light source is mostly continuous or the contrary. Amclaussen.

steven4872 (author)amclaussen2015-05-14

"Most LEDs produce light that is composed of narrow peak wavelenghts, thus, it has a discontinuous spectrum"

Single color LEDs are narrow specturm. About +/- 5nm from the specified wavelength. The most common blue wavelength available is 465nm while the most common read is 625nm.

There are two types of white LEDs phorphor and RGB. RGB LEDS have one red, one blue, and one green LED in a single package. The mix of these three colors will create what appears to the human eye as white light. White phosphor have a blue LED coated with phosphor. The Phosphor used today is typically full spectrum or very close to it. The best way to know if you have a full spectrum white LED is to look at its color rendering index. The scale is 1 to 100 with 100 being full spectrum. Most good quality white (Sylvania, fiet electric, and Cree LED lamps have a CRI of 80 or higher.

As to Seasonal Affective Disorder I would recommend a vitamin D supplement. most vitamin D in our bodies comes from UV light hitting the skin. A little comes from food. Most people in the US are deficient in vitamin D, especially during the winter months. fluorescent light create UV light and then use phosphors to convert the UV to white. White LEDs creat blue light, not UV. So a fluorescent lamp will have some UV leak out while a white LED will have no UV.

mart33n33 (author)amclaussen2015-05-14

Good thoughts. I'll try testing a full spectrum vs. narrowly defined spectrums and see what plants respond best to

aperkins01096 (author)2015-05-13

nice instruct able. Wondering what plants you're growing. I had great luck with lettuce, some luck with cucumbers.

mart33n33 (author)aperkins010962015-05-13

Unsure what the final mix will be. I'm thinking small, expensive produce that grows quickly -- sprouts, microgreens, etc. Will definitely post an update on which plants are most efficient

steven4872 (author)mart33n332015-05-14

There is one plant you might want to consider, duck weed, A very small plant that floats on ponds. Its not a food plant but with sufficient nutrients in the water and adiquate light it will grow very fast, Under idea conditions one plant will become 2 in a few days. then 4, 8,16.... It might be useful to quickly compare the lights and then switch to ordinary food plants.

JesseD8 (author)steven48722015-05-16

I remember reading in an article that Duckweed is a great thing to grow if you have an an aquaponics system because it can be used to feed the fish. It multiplies quickly so you get a good supply of it coming in continuously and you don't have to buy fish food so it's more input in the system that makes it sustainable. Also Black Fly Larvae was another thing you can feed to the fish and chickens that are also another option.

aperkins01096 (author)2015-05-15

re:duckweed - Don't know of what to use it for other than using it for fertilizer / compost (and possibly feeding to ducks). While it can be edible (see, I don't know if I'd go out of my way to grow it as a food.

hhill8 (author)2015-05-13

Just a quick note... Blue LED rope lights are ALL that is needed for growing leafy green-type veggies. Red and orange LED's do growing and fruiting. (Ie. for producing Tomatoes, flowers/fruits. Do a little research, and find the lights you need for the type of veggies you are growing. However, if you wish to have multiple types of veggies under the same lights, you will be best off with the full spectrum lights. Farmtek has MANY different types of lights, the staff are wonderful at answering all of your questions and problem-solving, not to mention ALL of their GREAT products! AND, they TEST all of their products themselves, so they are able to use their real-life knowledge to help you out.

I have a fodder system that I bought from them to produce organic feeds for my multitude of animals (horses, chickens, ducks, geese, turkeys, pheasant, quail, etc.) I can also use this system for microgreen production during the summer months when fresh greens are plentiful.

It is very nice to be able to produce, AND HAVE CONTROL over ALL environmental factors, fresh feed/food for both myself, my animals, and local restaurants.

Thank you for this tutorial! It is nice to check out many different ways to make hydroponic/aquaponic systems.

mart33n33 (author)hhill82015-05-14

Thanks! Great suggestion. I'll test red/blue/white vs blue/white for the microgreens and report back to you

sbsch (author)2015-05-13

fascinated by your lighting knowledge. I grew hydroponically using t5 HO's - how do they compare in your view

mart33n33 (author)sbsch2015-05-14

Thanks.. it's a great light. This one on Amazon is a really good value -- -- it outputs 20k lumens at 230 W, producing about 87 lm/W

cellihwd (author)2015-05-12

Great Idea!! I'm not particularly handy, but I believe I can do this. Thanks.

ac-dc (author)2015-05-12

You have a few misconceptions for indoor grows in otherwise climate controlled areas (in other words if you have A/C room cooling to keep temperature fair for humans).

1) Fluorescent tubes are still more cost effective when you include both initial cost and lumens per watt. Futher 22W of LEDs is not much to bother with and would only be good for roughly 2 sq. ft. if that. You can't claim lower power consumption is a good thing if it just means the plants don't get as much light for optimal growth.

2) Heat is not all that bad. Using fluorescents you often WANT their heat to stay in the area to heat it above the ambient room temperature more comfortable to humans, to rough 85F to 95F to improve germination rate, particularly for certain hot weather loving plants like peppers, okra, and more, but it will speed up germination of just about anything. However, once sprouted it is best not to subject things like herbs to temperatures over 80F as it will cause much sooner bolting to seed.

3) Fans are desirable! They help to dry the top soil surface to drastically reduce fungal growth, mites, aphids, whitefiles, etc infestations. They also slightly move the plants around encouraging them to grow thick healthy stems which is particularly helpful to make them more wind resistant if they were to be moved outside later, and encourage a little bushier shape instead of leggy but this also depends on amount of light and available space.

4) $78 for 22W of LED is not inexpensive. My DIY CFL (daylight hue) enclosure has a 6 + 2 pack of 14(?)W bulbs (over 7000 lumens) and everything else was scrap/salvage so it only cost the 6 pack of bulbs, about $18 at the time. Yes it uses more power but the light to total power ratio may be nearly as good and it would take many years of spring use to recover the savings from a > $200 cost conversion to LED bulbs.

txoutback (author)ac-dc2015-05-12

I agree with ac-dc and want to add this link to a solar powered hard drive fan:

steven4872 (author)2015-05-11

I built about a a year and and a half ago a red and blue grow light for my orchids. I also targeted the red and blue ABSORPTION wavelengths of Chlorophyll A and B. The results were mixed two did OK while 4 did nothing but grow more roots. doing more research. I found out the ACTION spectrum of plants. Unlike the ABSORBTION which shows the wavelengths most absorbed, The ACTIION spectrum shows which wavelength the plant actually uses to grow. Scientist that studied the action spectrum found that most plants actually do make use and green and yellow light.

With that knowledge I built a new grow lamp that focused more on white light with a suplament of 465nm blue and 660nm red. The three of the 4 orchids that didn't do much with the red and blue grow lamp quickly flowered. most of the others are showing growth.

So if you find a plant that does not appear to do that well you might want to retry the experment with that pant but under white light.

LoeS1 (author)steven48722015-05-12

Thx for that PDF-file... very interesting.

I use two T5-tubes with 6400K a 23 Watt as growing light for my seedlings.

Unfortunatly i made bad experiences with the lifespan of retreofit-growing-LED-bulbs and changed it back to tubes.

mart33n33 (author)steven48722015-05-11

Good call. The Ikea LED strips are only 2700k and don't outshine the red and blue lights, throwing off the natural ratio. I think adding one or two 6500K CFLs would likely double growth rate. Will test and report back. Thanks!

vmod32 (author)2015-05-12

I wish electricity in the North East was 12 cents per kwh. It's over double that right now. :(

starphire (author)2015-05-12

Just a few thoughts:

60 lumens/Watt is actually pretty lousy as LED light efficiency goes. IKEA's LED lights in general have lower efficiency and quality than name-brand bulbs because they are so price-oriented. You can easily get 90-100 lumen/Watt LEDs but not at rock-bottom prices (maybe $25 per bulb instead) - energy savings will easily make up for it in the long run, though. It makes me sad that IKEA puts on such a "green" front with their exclusively LED bulb line, but makes such a horrible compromise to match consumers' expectations of being a bargain source. In the case of LED bulbs, marketing wins over logic and consumers are being misled.

The kicker is that PAR-type LED bulbs are also pushing the envelope for heat in a package that size (that's an industry problem, but also an excellent reason to go for the highest lumens/Watt you can get for LED bulbs in this style). Those fins are ESSENTIAL to keep the tiny LEDs from cooking to death (just because you're not feeling the heat from a big hot bulb does not mean the poor LED chips are not literally at the boiling point of water). They normally rely on convective airflow past those fins. Which is partially blocked by the aluminum pans that contribute nothing to them (ALL of the LED light is already focused downward by the optics in the bulbs, in contrast to older styles of PAR bulbs). Fortunately the fins are still exposed to fresh air on the back side, I'm just noting that the pans are doing them more harm than good as assembled.

The LED strips get some benefit from the reflective pan since they are wide angle. So as a packaged light the pairing probably looks nice and works for the plants, but you could put some substantial ventilation holes in the pan near the LED bulbs and lose none of the light, that is the one thing I would suggest as an improvement.

tailslide (author)2015-05-11

Great idea! Fwiw I have found that white makes a better light reflector than mirror finish.

Ledtheone (author)2015-05-11

Very cool, how much distends Duse a light cover. Can't wait to see your other posts

seamster (author)2015-05-11

This looks like an excellent setup!

I think your image in the last step would make an excellent cover image for the intro! :)

mart33n33 (author)seamster2015-05-11

Thanks for the suggestion! Updated and added a few other pics I had from the build

seamster (author)mart33n332015-05-11


About This Instructable




Bio: Seafood is my specialty but my love of food justice, self-reliance and productivity knows no bounds. I grow food under my bed.
More by mart33n33:36 Cool Indoor Garden Ideas to Grow FoodBoquerones: Vinegar and Oil-Cured AnchoviesGrow Light and Irrigation Hood - 54W, 3300 Lumens, $18
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