I built this for my fiance, for growing herbs. We live in southern FL so It is really just an experiment to see if it works better than or equal to growing outside. Potentially this build is very customizable. You can use whatever you can find around the house and you could grow anything you like with it and expand the system as you like by adding more LEDs or different planters. You can also use bigger or smaller net cups. I will add some more pictures as the plants mature to prove it's functionality. I was inspired by seeing an aerogarden kit at the store and thought to myself that I could build that even better and cheaper. I am very happy with my results so far and I am looking forward to seeing how well the system performs.
I used 3 watt 6500k cool white LED stars because I have a bunch leftover from building an aquarium hood...I figure if they can penetrate water and make plants grow like they do, then they would work just fine for regular plants. I included a pic of the aquarium just to show how well they work for underwater plants.
Step 1: Items Needed
1) Large Plastic Coffee Can
2) 2" Net Cups
3) Black Spray Paint
4) 4x 3 watt 6500k Cool White LEDs mounted on PCB Star
5) 12 volt power supply rated 1.5 amp or higher
6) Aquarium Air Pump
7) Air Line Tubing
8) Air Stone
9) Plant Starter Plugs
10) Fertilizer Mix for Hydroponics
Step 2: Optional Items
Ok, let me start off by saying this project can be done with or without the following items. I happen to have a 3D printer so I designed my own net cups and a light fixture using 123D Design. This being said, you can use whatever you have on hand to make the light fixture. A small square of wood or aluminum suspended by a string over your plants will work, just epoxy the LED stars to it, solder the wires and it will work. 2" Net Cups can be easily purchased online as well. Part of keeping costs down is re-purposing stuff you may have lying around and being creative in your building process.
1) 3D Printer
2) Design Software
3) Small Piece of glass or plexiglass
4) Cheap 110v mechanical timer
5) 110v Power Strip
Step 3: Design Your System
Ok, I did not come up with the plastic coffee can hydroponic system. I found it online and improved on it, by adding the lighting system to it, hence the name "indoor hydroponic system".
Design your system on paper before you start, it makes building a lot easier later. As I said before, you can build the light fixture however you like, with whatever you want as long as you wire the LEDs properly. I used 123D Design to create my own net cups and light fixture parts and if you have a 3D printer I would highly recommend you design your own because you can customize it to your liking and it is a great way to hone your skills in designing your own printable items. I designed my own net cups because I wanted a stronger more re-usable cup that would print relatively easy. I will include pictures of my 3D parts so you can get an idea of how I did mine.
Step 4: Getting Started - Build the Planter
Drill three holes in the coffee can lid so your net cups drop in easily but don't fall through the lid. I used a hole saw and a cordless drill. You can use a razor knife or scissors to cut out the holes. Make sure the net cups drop in the holes easily. You don't want gaps where light can shine through the lid on the sides of the net cup so cut carefully ensuring the lip of the net cup covers the hole edges.
Step 5: Paint the Planter
This step is important, you don't want light to hit the water inside, as this will grow algae and rob the plants of nutrients. I used black spray paint but you can use any opaque paint and/or use a paint brush.
Step 6: Drill a Small Hole for Airline
Drill a hole so your airline can enter the lid, you want a snug fit. I suggest using black airline but I didn't have any on hand when I built this project. Thread the airline tubing through the lid with enough tubing that the air stone will rest on the bottom of the coffee can when you secure the lid. Put the air stone on and connect the other end to the aquarium air pump. Use a check valve if you plan to place the air pump below the water line of your planter.
Step 7: Drop in Your Net Cups and Fill With Water and Ferts
Ok, drop the net cups into the lid, secure the lid on the coffee can, mix your ferts with distilled or reverse osmosis water using the directions given with the fertilizer. I mixed mine in a gallon jug, I only did 1/3 of the recommended for starting my seedlings. Fill with the fert mixed water so the water line just barely touches the bottom of your net cups. fire up the air pump and your planter is done.
Step 8: Plant Your Seeds
Plant your seeds in the root plugs, I used Rapid Rooter plugs because they fit perfect in the 2" net cups. You can use any starter plugs you like, using 1 cm sized clay hydroton pellets or pea gravel around and under them in the net cup. You can also use rockwool, again it's your choice to use whatever you prefer. Drop your seeded net cups in the coffee can lid.
It will take a few days to weeks for your seeds to sprout, depending on the germination time that should be written on the seed's package, so you have time to build your light fixture.
Optional step, pour a small bit of hydrogen peroxide on the starter plugs after you drop them in and they have absorbed water. This helps prevent mold from killing your seedlings. I tried using sponge for a starter plug the first time and mold wiped out my seedlings.
Step 9: Build Your Light Fixture
You can build the fixture as simple or as complex as you like, I wanted mine to look nice so I designed it and printed it out. I used the plexiglass (or glass) as a moisture shield and I highly suggest this to prevent moisture from corroding your LEDs!
For this part you'll need to scrounge around your house to find a 12v power supply, I found one from an old DSL modem that fit the bill perfect. Each 3 watt star LED will need about 250 milliamps or .25 amps to operate so find a power supply rated for at least 1.5 amps or more.
Build your fixture, then arrange the LEDs in the fixture so you can see how much wire you will need for connecting them. Mark the placement in the fixture, 2" or more in between the LEDs. They give off some heat so you don't want them too close to each other.
I cut the small connector off the end of the wire and cut off enough wire to use to connect the LEDs. You will need to wire the LEDs in series for this to work. So use a voltmeter to determine the (+) wire on the power supply, solder that to the first LED's (+) side. Next solder a small wire to the (-) side of the first LED and solder the other end to the (+) side of the second LED. Continue this till you get to the fourth LED where you will solder the (-) wire from the power supply to the - side of the LED.
Verify that it works by plugging it in, if you made the connections properly the LEDs should be blindingly bright.
Now use epoxy or gel superglue to attach the LEDs to your fixture.
Step 10: Put It All Together
Place your light fixture so it is shining directly down on the net cups. If placed anywhere besides directly above, the plants will grow in the direction of the light.
Plug the light into a simple timer set to give 16 hours of light and 8 hours of darkness.
I am using mine to grow herbs but you can use it to grow anything from herbs, lettuce, tomatoes...if growing larger plants use the system to get your plants off to a healthy start then transplant them outside. I chose to use 2" cups but you can use one large net cup instead of three small ones, it all depends on what you prefer. I am also using two planters under one light, again this is up to you. You don't have to use coffee cans either, any plastic container with a lid will suffice.
Use your imagination, the whole point of this build was to grow plants...so no matter how you decide to build it, and no matter how fancy you make it, really doesn't matter as long as it works and grows plants... My seedlings are off to a great start and this was a really neat project that I learned a lot from.