Organic Hydroponics, Small Scale



Introduction: Organic Hydroponics, Small Scale

About: I am a student at Linn-Benton Community College in Oregon. Learning about botany and horticulture. I enjoy growing plants and building things from stuff.

Before I begin, I would like to shed some background on myself and this project.

I am currently a student at Linn-Benton Community college and soon Oregon State. My field of study is Horticulture.

Ever since I was small I had wanted to be an electrical engineer, but I found a stronger love for plants and all of the fun chemistry that goes on within them. I am attending college to learn instead of just get a degree, as my life goal is to own my own production nursery where I can experiment with any plant I desire and grow tropical fruits locally in Oregon.

Tropical plants intrigue me the most. I currently have two Starfruit trees and a bunch of Cherimoya seedlings (one of them is really cool). One of my favorites is my Mimosa pudica, it's one of the sensitive plants and reacts to touch.

This project arose from two classes that required a project in the horticulture field. To satisfy those I have decided to create this; a small scale, indoor, ORGANIC, hydroponic system.

Despite it being hydroponics it can still be organic, contrary to what some believe. The requirements for this project state that it must follow USDA Organic standards, which are listed online. Every aspect of my project will be organic except for two components: the adhesive and some of the seeds.

*If anything doesn't make sense or if I just didn't say something, ask in the comments. Either I or another Instructables user can answer them. This is for everybody to learn so please, ask away.

** I also take no responsibility if anybody gets hurt. Be careful. Get some help if you don't feel comfortable doing it.

Step 1: Location

I live in a small apartment, so being a plant guy is difficult. That's why last year I built myself a double decker propagation box.

My box is constructed out of a four door wooden cabinet I purchased from Walmart, a few surge protectors, two recycled computer fans, and a 300 watt full spectrum LED grow light (my favorite light so far).

The whole unit is plugged into a huge timer and sits in the corner of my room right next to my desk.

Step 2: What Is Organic?

When you hear or read the word Organic what do you think about? Do you think about not using chemical pesticides or fertilizers? Is that all you know about Organic?

Although the absence of synthetic fertilizers and pesticides, which are very harmful*, is a key point in organic agriculture it is so much more than that.

Conventional agriculture often depends on the use of fertilizers to create a nutrient supply and pesticides to control plant disease. Whereas Organic agriculture relies on taking greater care of the soil so that it can provide the nutrients plants need. The use of pesticides is replaced by practices that promote strong, healthy plants that can fend off pests on their own.

Organic agriculture depends on the soil. The soil is tended and allowed to develop into something that can feed the crops on its own and provide habitat for a number (a large number) of soil-borne organisms. This biodiversity allows many nutrients to be stored in the soil as well as reserves of water and air.

In organic agriculture farmers must not only raise healthy, clean crops without nasty chemicals but also develop a solid business plan that includes ways they can improve.

In order to become certified as organic a farmer needs to follow the rules and regulations laid out by the National Organic Program (NOP).

The United States Department of Agriculture Organic Regulations can be found at

*Although many chemicals used in agriculture are not directly harmful, they often cause changes that lead to bigger problems such as eutrophication in the Gulf of Mexico which is mostly caused by algae blooms that feed off of excess fertilizer flowing out of the Mississippi River.

Step 3: Measurements & Design

I made the hydroponics system to fit inside my grow box. So with that in mind, I measured my grow box and found that I had a roughly 10x14 inch space to work with.

I designed a system that has a footprint of 8x14 inches and stands 8 inches tall. It is composed of two parts: a lower, larger reservoir and a grow bed on the upper level. Both halves are 4 inches tall.

As you can see in the picture, the grow bed is two inches shorter (length wise) that the reservoir.

Step 4: Materials & Equipment

Bill of Materials:

  • At least 5 Dollar Tree picture frames (the amount will depend on how big your design is), or an equivalent amount of glass. I chose these frames because they are cheap, but they are very thin and break easily.
  • A small pump (and a power source for it)
  • Painters tape
  • 100% silicone (food grade prefered)
  • Foil tape
  • Food grade PVC tubing that will fit your pump
  • 1/4 inch diameter food grade tubing (for the siphon)
  • a 5 inch long piece of 1 inch PVC pipe (for the siphon)
  • A cap to fit the PVC pipe
  • Seeds of your choice, Organic prefered but if Organic seeds are not available others can be used.
  • Peat pellets (to start seeds in)
  • Hydroton or equivalent material (hazelnut shells work and are cheap here in Oregon)
  • A timer to control watering schedule (a timer that can be controlled at the minute scale would be best)


  • Saw
  • Drill and glass drill bits
  • A straight edge/ruler
  • A glass cutter or a carbide scribe
  • A sharpie of your color choice (I chose blue)
  • Scissors


  • Adapter flange for PVC

The pump that I used was salvaged from a tabletop fountain I found at a thrift store. I then soldered the pump to an old 5volt phone charger.

I would like to say that if you chose to use dollar tree frames, buy extras. I broke several before I got down the method for cutting glass. They are also very thin (about 1/16 inch). Any other glass will work, stainless steel could even be substituted if you have the tools and know how to weld.

Step 5: Building the Glass Part

Cutting The Glass

This for me was the hardest part, mostly because I kept breaking glass.

First you need to cut out all the pieces.

  • One 8x14 inch piece (for the bottom of reservoir)
  • One 8x12 inch piece (for the bottom of the grow bed)
  • Two 4x14 inch pieces (for the reservoir sides)
  • Two 4x12 inch pieces (for the sides of the grow bed)
  • Four 4x8 inch pieces (for the ends)

I recommend using an extra frame and practicing scoring and breaking the glass.

Use a solid flat surface for the glass work. I used a board on my floor but a table or countertop will work just fine.

To cut the glass you need to first measure and mark the length of your piece with the sharpie. Next you will need to hold the straight edge on your line firmly. Then, holding it perpendicular to the glass and applying firm pressure, use the scribe to score the glass along your guide line using the straight edge to, well, to keep it straight. Its best to just do one straight score, multiple passes can cause chips to occur.

Once the glass is scored you have to break it. I found two methods that worked well on this scale.

The first method is to flip the glass over (so the score is face down) and place it on some cardboard or a similar surface and press down on the score with your fingers until it breaks.

The second method is to simply hold the glass in your hands (score side up) with your thumbs and forefingers, then simply bend the glass at the score until it breaks.

If your score was clean and straight enough you should get a nice break.

Now repeat those steps until all the pieces are cut.

If you have trouble Google "Cutting Glass", that's what I did.

Drilling The Hole

I did not do this because I changed the design halfway through, but be sure to drill the hole for the siphon in the 8x12 inch glass piece before gluing it in place.

To drill the hole grab a glass cutting bit and a drill. Mark where you want the hole to be. Then place the glass piece on a flat sturdy surface. Hold the drill bit perpendicular to the glass and apply a small amount of pressure. Start the drill and hold at a steady speed (about 200-300 rpm). Occasionally stop to clear the hole of glass dust. Once the glass is punctured move to an area that will allow the drill bit to go through cleanly.

If you are using thicker glass you might be able to hold the piece over a sink and drill it.

I highly recommend practicing on some scrap glass before hand. I broke several pieces of glass before I got it down. Even then I still fractured my glass in several places.

Assembling The Pieces

I chose to hold the pieces together with tape while I glue them. Start with the bottom reservoir piece and tape the two long sides and one of the ends. (There is an example drawing of how the pieces go). After they are all taped firmly run a bead of silicone along each corner to glue them together

After the first three sides are mostly set, roughly 20-30 minutes, place the grow bed bottom (the 8x12 inch piece) on top, tape and glue it.

Once the whole bottom piece is set you can attach the other end piece with silicone then tape it to hold it steady.

Repeat this process for the top section.

Once the silicone has set you can remove the masking tape.


To reinforce the seams run a bead of silicone along them and then cover that with foil tape.

Using the silicone on this step is optional, but I recommend it for extra protection against leaks.

Step 6: The Irrigation System

For my water circulation system I chose to use a small pump in the reservoir and a bell siphon in the grow bed.

I will start with the pump. The pump is a 3volt mini-aquarium pump. I have it soldered to an old motorola phone charger that puts out 5volts. I would recommend using the same voltage that your pump requires. This one works fine running on 5volts but is significantly louder than 3volts.

Glue your pump to the bottom of the reservoir with silicone. Don't use too much. Use just enough to cover the surface of the pump that is being glued.

On the outlet of the pump is the 1/4in PVC tubing. Cut a piece of tubing around 10 inches long, or long enough to run from the pump and over the wall of the grow bed and down into the grow bed. My pumps' outlet is just larger than the inside of the tubing so I simply pushed it on for a nice friction fit.

After you have your tubing cut, glue one end in one of the front corners of the grow bed leaving about 3mm of space between the end of the tubing and the bottom of the grow bed, this allows the supply line to siphon the water back down once the pump has turned off.

While the tube is setting you can assemble the bell siphon. This siphon consists of: a larger piece of pipe that has a cap on one end and notches cut in the other, a smaller piece of pipe attached to a coupler, and a tube inside the smaller pipe.

While you can build the same thing I did, I wouldn't recommend it. I had different plans and changed halfway through. To make your siphon simply take your piece of pipe, put the cap on one end and cut some notches in the other end. The notches shouldn't go more than 1/4 inch up the pipe. Then take your tubing and push it through the hole of the grow bed about 1/2 of an inch and glue it in place. The tube must extend down below the bottom of the grow bed to create enough suction. The top of the tube is as high as the water will go, so cut the tubing where you want your water to drain. My tube is long enough to allow the grow bed to fill with 2.5 inches of water. After the tube is set simply apply a thin layer of silicone to the bottom of the pipe and set it on top of the tube so the tube is inside the it.

Once all the silicone has set you can attach your pump to its tube and put some water in for a test run.

Perform your test run over a sink or someplace that can get wet.

To test, simply fill the reservoir about 3/4 of full, power up the pump and let it flow. Look for any leaks.

Step 7: The Herbaceous Selection and Grow Bed

Mmmmm, Plants

To find what you want to grow, start with what you know and try to find organic varieties. Herbs are very popular and very easy to grow.

For something this small I find it easier to use plants that don't get very large but can still fill the area.

It is possible to grow almost anything in a stable hydro system; I chose to use some herbs.

My selection included Sweet Marjoram, Summer Savory, Fragrant Chives, Curled Chervil, and Anise.

Although the seeds I used were not 100% certified organic they were organically grown.

To start the seeds first soak your peat pellets (if using a different starting material follow its instructions). Once they are fully saturated you can plant the herb seeds. A good rule to follow for seeding is to plant the seeds 2 to 3 times their width in the soil/substrate. So if you have big seeds that are 3mm wide they can be planted up to 9mm deep, and depending on what they are they can be planted deeper. Very small seeds can be sprinkled on the top and lightly covered.

The Grow Bed

Before putting anything in the grow bed be sure to wash it. If you are using hydroton rinse it thoroughly as the dust that comes with it can clog your pump. Hazelnut shells should be rinsed as well.

After your media is clean you can fill the bed with it. I ran out of hydroton so I mixed hazelnut shells in with it.

Step 8: Plant Nutrition

To supply the nutrients my plants so desperately need, they were kept in the peat pellets too long, I will use a compost tea made from certified organic compost I bought from the store. I simply filled a jelly strainer bag (cotton) about halfway with compost and then set it in the reservoir to steep. Once the plants start showing signs of deficiency it's time to replace the tea. It's good to know about how long a given amount of compost will feed your plants. It's even better to replace the compost in the bag before it is deprived of nutrients.

Over time I will experiment with adding different amendments to the tea to make a more nutritious mixture.

Experiment for yourself as well, you might find something that works better for your plant selection.

*I would like to say that you should not drink your compost tea, it is good for plants. It just might make you sick.

Step 9: Final Thoughts & Considerations

If I ever build one of these again I would use thicker glass and higher quality bits. I would also use a newer pump.

The next one of these I build will be larger so that I can raise fish and do Organic Aquaponics (maybe a future instructable?)

I hope you found this at least mildly educational.

I will update this periodically with pictures of my plants' growth.

I also would be very glad to hear any constructive criticism and will gladly answer any questions you may have, just post it in the comments.

Step 10: My Grow Box (Bonus Material)

The box is made from a Mainstays Storage Cabinet purchased from The light is a Galaxy Hydro LED light bought from Amazon. The fans are recycled 12 volt computer case fans powered by a recycled 12 volt wall wart (AC/DC adapter). All of which is powered by two power strips glued inside the box near the top. The power strips were cut and wired together, then plugged into a 6 foot extension cord which leads to a timer plugged into a surge protector. I lined the box with some white plastic and foil tape.

Tools required: screwdriver, saw, pliers, drill, or a leatherman and a drill

The steps to make the box are:

1 Assemble cabinet (if not already) and glue the power strips to either the ceiling or the walls near the ceiling.

2 Cut holes out of the back of the box (the thin cheap particle board) the size of your fans, as well as one or more holes near the bottom for air intake. Note the size of the box when choosing fans. Try to get fans that will evacuate all of the air within the box in less than ten minutes. This insures adequate air flow.

3 Insert fans and anchor how you see fit. My fans are simply friction fitted in (ask me why in the comments).

4 Wire fans to wall wart and plug that into one of the power strips located inside the box.

5 This one can be handled different ways. The LED light comes with wires attached to hang it from a single eye bolt. But this wire is long and using it will put the light somewhere in the middle of the box, which is just ridiculously close. So I cut two pieces of paracord and made my own hanging system. I put 4 eye bolts into the ceiling and threaded the paracord through. This allows me to hang the light as close to the ceiling as possible.

6 Once the light is installed its time to plug everything in and turn it on. Check everything to make sure it works.

7 Either line the interior with a reflective material or paint it white.

8 One thing you could do that I have not is to line the door with something to keep light leaks down. The foam used for insulating doors and windows would work. Otherwise the small gap between the doors and the box allows air to flow through and makes for an interesting light effect.

Links in case above does not work:

Mainstays Storage Cabinet

Galaxy Hydro LED Light

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