To me, urban farming is about maximizing yield in tight spaces. I think this design does just that. You can see in my pictures a happy, healthy "Wenk's Yellow Hots" pepper plant. This method of growing is fantastic for peppers and tomatoes! I used all readily sourced materials from either Amazon.com or a similar site. The buckets were from the Home Depot, but any 5 gallon buckets with tight fitting lids would work fine (best if "food safe"). The system consists of 3 basic components.
- The base/reservoir. The plant is grown in a net pot in the lid of the bucket, and nutrient solution is held in the bucket itself. The plant actually roots down into the highly aerated nutrient solution rather than soil.
- The light top. This is the bucket where the main lights live. In this design, I used 5 flat Philips LED lightbulbs. The bucket is lined with mylar to make the entire chamber reflective and maximize light distribution.
- The spacer. This bucket is added to give the plant more vertical room to grow. The inside of the spacer bucket is lined with mylar and then with a 5 meter LED strip light (5050 SMD, 12v). This surrounds the plant with light from all sides as well as the light from the top.
Step 1: Gather Your Tools and Materials
You'll need the following tools and supplies for construction of this system. Luckily many of these things you either already have or will be able to use for many other instructables!
Clay pebbles (Hydroton type grow media)
You'll need the following parts to construct a basic system. I've included links to some of the components I used. These are just examples. The system will work with many different types of these basic components.
For the Base/Reservoir:
1x 5 gallon bucket (Black to keep light out. No light, no algae!)
1x Nutrient dripper (includes nutrient level indicator)
1x Aquarium air gang valve (This allows you to split your air delivery if you wish to add additional airstones and/or dial back particular lines. Useful for limiting the flow of the dripper airline for instance.)
3x Small airstones (for additional aeration when used with the 4 way gang valve)
1x Battery backup air pump (If the power goes out, this keeps your nutrient solution aerated so your plant doesn't suffocate! I recommend replacing the small airstone this comes with and using a larger airstone for this pump as well.)
For the Light Top:
5x LED light bulbs 75-100w equivalent (Flat are nice for space savings, but optional. Color temperature isn't super important, but you can mix cool white and soft white bulbs for a more broad spectrum of light.)
1x 120mm AC cooling fan (Used to exhaust in warm interior air to control temperature in bucket.)
1x Black spray paint or black duct tape (Use to cover the outside of the bucket. This will minimize light penetration from OUTSIDE the bucket. This is mostly important for plants that require strict light and darkness schedules.)
For the Spacer(s):
1x 5 Meter 5050 SMD LED light strip with power supply (warm white, self adhesive, waterproof)
1x 80mm AC cooling fan (Used to draw in cool outside air to control temperature in bucket.)
1x Black spray paintor black duct tape (Use to cover the outside of the bucket. This will minimize light penetration from OUTSIDE the bucket. This is mostly important for plants that require strict light and darkness schedules.)
Step 2: Build Your Base/Reservoir
There are a few ways to do this but if you bought the parts I linked to in the previous steps it is fairly simple.
First, install the water level indicator tube.
- Use your ruler to measure up the side about 2 inches from the bottom of the bucket and make a mark. If you have a black bucket, use a piece of tape, if not, use a sharpie (they mark plastic really well). Measure another 6-8 inches up directly above with your first mark. Make a second mark. It's important that this hole is above the height of your max fill line on your water level indicator tube.
- Drill holes where you marked in step one. The bottom hole is the bigger one. Being about 2 inches from the bottom should give room for the grommet surround inside. The hole should be about 3/4 inches, but it's best to use a step bit to get it just right so the grommet fits snug in the hole.
- Drill a second hole where you marked, about 6-8 inches above the first hole. It's important that this second hole lines up with the center of the of the first hole so your tube stands straight up and that it is above your max fill line on your indicator tube. This is a 1/4 inch hole. Again use a step bit to find the right size to get a nice snug fit for the retainer ring.
- Carefully use your utility knife to trim up any excess plastic burr that might be clinging to the sides of your freshly drilled holes.
- Insert the rubber grommet in the lower hole and the retainer ring clip in the top hole.
- Attach the tube to the elbow, then push the elbow into the rubber grommet. Bend the tube as needed to slip it through the retainer ring.
Here is a video from the manufacturer that shows the basic idea.
Second, install the dripper ring and riser tube. Drill holes for air lines.
- Shorten the dripper ring tube as needed to make it fit the inside diameter of your net pot. This cuts easily using your trusty utility knife. My picture shows using a 5 inch net pot. That's about as small as you can go with this dripper ring kit. On a 6 inch net pot, your tube will be around 18 inches, but you're best off cutting a bit longer and test fitting. Trim as necessary so the ring fits inside your specific net pot. Make sure that the holes in the drip ring are facing down.
- Snip out a hole in the bottom of the net pot (close to the edge) just big enough to allow the riser tube through.
- Drill small holes for air lines (about 7/16 inches, again use the step bits to find the right size for a snug fit). You'll need one hole for your main air line, one for your battery backup pump air line (if you're using one), and one for your drip ring. Drill these three holes opposite your water level indicator tube, the exact location doesn't matter, but you'll want them high enough that they will not ever be near your water level.
- Drill another air line sized hole in the bucket lid, an inch or so from your net pot. You'll route your drip ring air line from the outside, into the reservoir then up through this hole to finally attach to the drip ring. You can see that airline in my picture.
Finally, install the air lines and stones.
You can see from the picture that I use the optional air gang valve (so I can actively run multiple smaller airstones in addition to my main airstone) and battery backup pump. If you decide to use the air gang valve, your main air line still goes directly from the pump to the main air stone (bypassing the valve). The drip ring air line will go to the valve as will any other lines to decide to run for extra air stones. Obviously, using the valve affects the length of your other air lines. Keep this in mind. The instructions below assume you are NOT using the optional valve.
- First decide where your air pump will sit. I like to keep mine directly next to the bucket(s) it serves.
- Next, we'll measure the length of our main air line. Grab your flexible tape measure. Measure from the bottom of the bucket, up over the lip and down the outside. Write that measurement down. This is the minimum length you should make your main air line. It should give you about 6 inches of slack assuming you use the air stone from my parts list and that your air line holes are a couple of inches from the top of the bucket. Keep in mind, that you need enough air line to get to where ever you plan on putting your air pump. Like I said, I like to keep my air pump right next to the bucket so this measurement works for me. If you need to, feel free to add length to this.
- Next is the air line for the drip ring. It's best to test fit this line to find your length. Feed a long length in from outside the bucket, route it up through the hole you drilled for it in the lid. Make sure there is enough slack in this line that it doesn't kink on any of the sharp turns it has to make. Don't attach this line to the ring yet. Once you're confident that you have enough length to get to your air pump location, go ahead and make your cut.
- If you're using a battery backup pump, I recommend that you use another air stone identical to your main air stone and the same length of air line as your main line. You can see from my picture that I use the clip on the back of the battery backup pump to hang it on the handle of the bucket.
- Now that you have all your lines cut to length, attach your air stone(s) and route your lines out of the bucket and to your air pump(s). Route the drip ring air line, attach it and install the lid.
Optionally, install the fill tube.
- Stand your PEX/PVC tube up next to the bucket. You'll want the tubing to be about 6 inches taller than the bucket. Cut to length with your PEX/PVC cutter.
- Drill 1 inch hole (ensure it is a snug fit with your PEX/PVC tube) in the side of the bucket with your 1 inch hole saw bit and clean up the hole with your trusty utility knife. The most important thing is that the hole is above your maximum water height. You can tell what that mark will be based on your already installed water level indicator tube. Insert your fill tube and angle the tube downward to the bottom of the bucket insert rubber stopper to keep debris out of your reservoir.
Optionally, create a light blocker disc (Used to stop algae growth on the surface of your grow media.)
Doing this gets you a head start on the next step as you're going to use the bottom of the bucket you use for the Light Top.
- Grab one of your white buckets that you'll be using for a Light Top. We're going to cut the bottom out of it. I like to get this started by drilling a small hole at the edge where I want to start cutting. We're going to cut the bottom out but leave the heavy, hard edge. You'll use your utility knife to do the actual cutting. Take your time, wear some Kevlar gloves if you have them. It may be helpful to drill multiple holes around the edge to give your knife (and your arm!) some relief along the way.
- Once you've cut out the bottom, we need to measure out a circle about 7 inches in diameter. Grab your ruler/tape measure and measure 3 1/2 inches from the nipple in the center of the bucket bottom (mine has a nipple with a 2 inch circle around it). Mark that with your sharpie. Do it 6 or 8 times (more if you want a nicer circle) around in a circle from that center point. Connect the dots and you should have a 7 inch circle (more or less). You will cut this disc out with your utility knife. I recommend making several cuts NEAR your line and then trimming it up afterward to get a cleaner circle.
- Drill out the center just inside the 2 inch circle in the middle. Use a hole saw bit for this, 1 1/2 - 1 3/4 inches, your choice. The plant will grow up through this hole and the stem of the plant will need room to grow thick.
- Wrap the disc in black duct tape or black spray paint for light blockage.
The Base/Reservoir bucket is now complete!
Step 3: Prepare Your Light Top
In my pictures, you can see I went with a more DIY option on my light sockets and wiring. It's a lot more work to wire them up like I did, but you end up with a single power cable rather than the bundle you end up with otherwise. I'll stick to the easier setup for this instructable.
Drill your holes for your lamp holders:
- Put the lid on the bucket and measure about 1 1/2 inches below the bottom edge of the lid. Mark this point in 5 equidistant points around the bucket. You can use your flexible tape measure to get this exact, or eyeball it. Be aware that if the points aren't evenly spaced you might have trouble fitting all 5 light bulbs in without them touching each other.
- After you've marked your evenly spaced points, drill holes for your lamp holder sockets at these points. Use a 1 1/2 inch hole saw bit for this. The holes need to be about 1 5/8 inch in diameter, though 1 1/2 inches will get you a snug fit with a little help from your old friend the utility knife.
Cut the bottom out of your bucket:
If you made a light blocker disc in the last step, you already did this part. Go ahead and skip to the next part (cutting the fan hole).
- Pretty self explanatory. I like to get this started by drilling a hole at the edge where I want to start cutting. We're going to cut the bottom out but leave the heavy, hard edge. You'll use your utility knife to do the actual cutting. Take your time, wear some Kevlar gloves if you have them. It may be helpful to drill multiple holes around the edge to give your knife (and your arm!) some relief along the way.
Cut a fan hole in your bucket lid:
- We're looking for a 120mm hole directly in the middle of the lid. To do this, use the little plastic nipple left over from manufacturing that is directly in the center of the bucket, measure 60mm out from that in 6 or 8 places. Then connect the dots.
- Place your fan directly over that circle you just drew and mark out the screw holes. Set the fan aside.
- Drill our the screw holes and a starting hole and break out your utility knife. Time to do some more cutting.
- After you've cut out the fan hole, set the lid aside.
If you've used my shopping list, this bucket is white and therefore pretty well reflective inside. If you have any other color bucket, you should consider stopping here and either painting the inside with some white spray paint or lining the bucket with some mylar sheets and spray adhesive like I did with my orange Home Depot buckets.
If you are growing photo period sensitive plants, this is also the time to paint the outside of the bucket black (or cover it with black duct tape for even better light blocking properties.
Step 4: Assemble Your Light Top
At this point its time to start putting the pieces of your Light Top together.
- Screw your fan into the lid (or use zip ties as I did) being sure that the airflow is pointing up or away from the bucket lid. You can tell the direction of the airflow based on a small arrow on the side of the fan. Put the lid securely on the bucket.
- Round up your lamp cords. Install them through the holes we cut earlier and tighten down the retainer nut. Not too tight, the lamp holder should be a snug fit even without the nut. The nut is just insurance.
- Group the cables up nicely to one side of the bucket allowing some slack on all of the socket ends (especially on the opposite side from your grouping). Bundle the cords together with zip ties snugly (but not too tight) every 6-8 inches. Plug the ends into your power cord splitters.
- Plug the lid fan into one of your power cord splitters.
Your Light Top is complete!
Step 5: Build Your Spacer
This bucket is designed to be used as your plant grows too tall to fit in a single bucket. You can use a full height bucket here or cut your bucket down to size, your choice. The key parts of this spacer are the cut out lid and bottom, the light strips and the intake fan. Lets get started by cutting the bottom of the bucket out.
Time to cut up another bucket:
- This is the same process as before with the Light Top. Drill a hole in the bottom of the bucket at the edge to help you get started. Cut the bottom out with your utility knife.
- Now we'll cut a hole in the side for an intake fan. This is optional but recommended. Measure about 5-6 inches from the bottom of the bucket and make a mark. This is your center point for your fan. Using your 3 inch hole saw drill out a hole for the fan at that mark. Clean up the edges with your utility knife.
- Hold your fan up to the hole you just made, line up the fan and mark holes for the screws holes with your sharpie. I like to mount the fan with zip ties rather than screws. This is your choice. It's not crucial that the fan makes a tight seal against the side of the bucket (it would be pretty hard to do that without deforming the bucket).
- To drill a hold for your LED lights power connector, measure about 1 1/2 inch from the bottom of the bucket. Mark that point with your sharpie. Drill it out with a step bit to just the right size that allows you to pass through the power connector of your LED light strip. You'll feed that power connector out through this hole later.
- Grab the lid now and measure about an inch in from the inside of the lip on the top of the lid. Mark it with your sharpie. Do this every few inches around the lid and then connect the dots. You're going to cut this out now. Same process as cutting the bottom of the bucket. Keep in mind that your light top will rest on this ledge that you're creating. So while you want to keep it close to the edge to allow more growth space for your plant, you also need enough of a ledge that your light top has some place to rest. After you've removed the middle of the ring, you can optionally cut the ring that's left in half. This way, if/when you need to remove it with a fully grown plant in the middle (handy when pruning and cleaning up debris), you don't have to pull it up over the whole plant. Just pop off each side.
At this point, if you've used a white bucket, you can move on. Otherwise, just like the Light Top, you'll want to either paint the inside white or line it with mylar. This is also the time to paint the outside black or cover with black duct tape if you are planning on growing photo period sensitive plants.
Mount the LED light strip:
- The LED strip from my parts list is self adhesive. If you bought that one, its easy enough to mount it inside your bucket. I recommend that you put the power connector through the hole and hold it in place with a piece of tape temporarily while you work. Working from the bottom of the bucket to the top, slowly remove the backing tape to expose the adhesive and press fit the led strip in a spiral around the bucket. When you reach your fan hole, keep going. it's okay if you run your lights in front of the fan a bit. You want to shoot for less than an inch between your rings to get good coverage, but you don't need to be too precise with this and its definitely okay to stretch that to 2 inches as you pass your fan hole for less air flow blockage.
- When you reach the top of the bucket, if you have left over strip, you can cut off the excess. Just keep in mind that the cut mark will not be waterproof, so you need to cover that end with some tape or clear nail polish.
Connect your parts:
- Press on your freshly cut lid ring.
- Connect the power brick to the LED power connector that's hanging out the side of the bucket and plug the power brick into one of your power splitters.
- Attach your fan to the side of the bucket making sure that the airflow indicator arrow is pointing toward you bucket. Plug the fan into one of your power splitters.
Your Spacer is complete!
Step 6: Assemble the Pieces and Start Growing!
If you start your seeds with the paper towel method, they're easy to transfer directly to a moistened rockwool plug, nestle that plug down into your hydroton and turn on your system. Some tips to get you going:
- NEVER turn off your air pump. Your plant will suffocate quickly without the air being pumped into the nutrient solution. This is especially crucial later as your plants roots grow down and become submerged.
- On the topic of roots, once your plant grows sufficiently that your roots touch the top of your nutrient solution, you can turn off the drip ring air line and hook up an additional airstone if you'd like. At that point the plant can directly pull from the nutrient reservoir and you'll see rapid growth begin as the roots start to grow and FILL the reservoir. Remember, healthy roots = happy plant. My picture shows what healthy roots look like.
- Don't let your Reservoir run dry. Initially, you won't have to add nutrient solution very often. But as your plant grows, you'll need to add to the bucket more frequently. With a full grown Wenk's Yellow Hot pepper plant (what I was growing in these pictures), I typically had to refill the bucket once a week. This is easy with a funnel stuck into your fill tube.
- Start with just your Base/Reservoir and Light Top buckets. Keeping the main lights closer to your seedling is crucial to a fast start.
- It's a good idea to always have your exhaust fan (on top) running, but you might find that the intake fan is only needed periodically depending on your plant and the room your bucket is sitting in. Some plants like warmer conditions, some cooler, some like warm days and cool nights. The intake fan helps in some of these scenarios.
- If you put your bucket on a WeMo switch, or similar device, make sure that your air pump is NOT connected to it. Remember, your air pump must ALWAYS be running.
That's pretty much it. Always follow the instructions on your nutrient bottles. I strongly recommend using nutrients that do NOT have a lot of sediment in them. If you do, you'll have to periodically flush out your Reservoir. The easiest way to do that is to have a second Reservoir ready to go and move the entire plant and light top to that clean Reservoir. Or avoid that entirely by using clean nutrients like the ones I linked to in my parts/supplies list.