How to build a grow box
A closed grow box system will enable you to create and control your own growing environment such as the sun, rain, wind, air, nutrients and pest control. I have recently decided to build a grow box that measures 5'x2'x2' so it will fit in my tiny apartment. This grow box is to help with my interest and love for exotic plants. My intention of this post is to inspire people with my ideas just as other peoples posts have inspired me. This is my first instructable, long time follower. So, please bear with me and gentle.
Step 1: Basic frame
The first step I took before going out and buying materials, was to determine exactly what I needed to minimize cost by not purchasing any more than I had to. I did this by using a free program downloaded from Google called Google Sketchup. I highly recommend it, because it let me build the box in 3D and to scale using the handy tape measure tool it comes with. The program is very easy to use. It took me less than a day to get a basic understanding of it. The total for all the wood used for this box was $52 at home depot.
2 - MDF sheets. 4' x8' x 1/2" $18.99 each
7 - 2" x 2" x 8' pieces $1.55 each
Optional items (well worth it if budget permits)
4 - Caster Wheels $3.79 each
16 - Bolts, Nuts, Washers (1/4") about $5
That's the entire list of needed and optional items. I already had wood screws. I used 2.5" all purpose screws for the frame and 1.25" #10 wood screws to attach the MDF to the frame. I printed up a template for the cuts needed to be made to the MDF and the dude at Home Depot cut it for me. 6 pieces total, 3 pairs of the same size pieces. Living in an apartment, this would have been difficult, however, I did cut the 2" x 2" pieces myself.
I had originally planned to make the box only 4' tall but wasn't sure if that would be enough room. However, a 4' tall box would only require one piece of MDF almost cutting the price of the box in half.
MDF pieces are:
1'11" x 4'11" (x2) front panels
2' x 5' (x2) side panels
2' x 1'11" (x2) top and bottom panels
As far as the 2"x2" cuts go here they are:
1'8" (19") x12
5" (60") x4
Here is the base assembled. Two of the 2x2's are flush with the edge and the other two have a half inch gap for the front and back panels to rest on. The sides will be flush with the ground. It will make sense if it doesn't now if you see the Sketchup file.
Part of the frame assembled. Depending on how much room you want to leave for the lights determines how far from the top the second cross piece is attached. I will be leaving roughly a foot of space because I want to put a piece of glass to isolate the light from the chamber. I will be giving the light its own ventilation independent of the grow chamber.
Next I attached the two frame pieces to each other.
After that, the frame is ready to be inserted and attached to the base.
Step 2: Inclosing the grow box
The side panels are now ready to be attached. However, I have chosen to put some mylar ($20 for a 25 feet roll at the hydro store) on the panels before doing so. This not only conceals the edges of the mylar, but will secure it too once attached to the frame. I did this by using 3M spray glue ($13 at Home Depot) on the panels and them unrolling the mylar onto the panel keeping it nice and neat.
Someone gave me the brilliant idea of putting wheels on the box for obvious reasons. Anyways, I should have put the wheels on earlier on in the construction but it wasn't a problem. I flipped the caster over and used it as a template for where to drill my holes from the inside. Next I inserted the bolts, washers and nuts and now its mobile! Now attach the sides with a few wood screws and you have a finish a project! I decided to wrap the mylar around the exposed frame just to be on the safe side. Here is the structure.
Step 3: Ventilation in the Light Chamber
I did a lot of looking around for fans. The fans that I found should work nicely for such a small grow box, they are computer fans. The fans specs are: Dimensions: 80 x 80 x 25mm Fan Speed: 2000 RPM Air Flow: 26.8 CFM Noise: 21 dBA Power: 12V, 0.12A I am planning on using one fan for the light and two for the grow chamber. I picked these fans up for only $4 each! Both fans together will replace the air in the grow chamber 3.35 times a minute, or once every 18 seconds. Since the minimum is once every 5 minutes, this should be more than enough. The one fan in the light will replace the air at twice the rate compared to the grow chamber, or every 9 seconds. A picture of the fans that I will be using Now that I have the structure finished it is time to install the ventilation and lighting. First, I will install the ventilation for the lighting that will be added later. I cut two holes for the fans to go into. I used a 1" hole saw drill bit in the shape of the fan and cut out the notches with a saw. There are way more efficient ways of doing this, but it worked with the tools I had available. In the end, the fans fit right into the holes. Any spaces left over will be filled in or covered up. The fan fits nicely. I wired them to a universal power adapter I bought at the Depot for $12. This stepped down the voltage from the wall preventing me from blowing any more up. (I had to try it once.) Just like the movies, a pop and a cloud of smoke. Typically 15 amps come out of the wall and the little fans only require .12 amps. Here is a picture of the power adapter that I wired the fans to, to be on the safe side, and to keep the fans from blowing up. I have added a few pictures to help show the rewiring process. I just cut the tip off and spliced it to the fans using an RCA cable. The RCA cables work nice because it has two conductors inside, just like the fan, keeping things neat. I also attached some RCA cable to the fans to give me more length so the two fans can be connected around the back. It was pretty easy to connect, just keep it consistent. I connected the red to white, and black to the shield and it worked great. Then the other.. Then I wrapped it all up in electrical tape to keep it all secure and resistant to moisture. In the end, I put the intake in the back lower corner and the exhaust in the front upper corner since heat rises, that's the best place to remove it. There will be a piece of glass separating the grow chamber and the lighting chamber. The following picture shows the grow chamber and the two locations of the ventilation. I connected the two fans together, then a wire to attach the two connected fans to the power adapter. A couple safety features to protect against me in case something gets pulled on for some reason.
Step 4: Light in the light chamber
Now it is time to put up the light fixtures. It only took two screws to install the MH fixture. Next was the HPS. I installed the fixtures so I just need to remove the bulb when I'm not using the other. A picture from the bottom of the box looking up to the lights Q When should I use a Metal Halide (MH) Plant Grow Light? A Metal Halide (MH) lamps produce a balanced light spectrum closest to natural light. Plants can be grown from start to finish using metal halide plant grow lights. MH is the best type of light to be used as a primary light source if little or no natural sunlight is available. Metal Halide's balanced spectrum contains the common blue and red wavelengths needed for rapid foliage growth. Q When should I use High Pressure (HPS) Plant Grow Lights? A High Pressure Sodium is 10-15% more energy efficient than Metal Halide light but does not have a balanced spectrum. HPS emits an orange/yellow light similar to the sun's spectrum in the mid day. HPS is best used as supplemental light and is particularly good at promoting flower growth. Next up will be the air filter and ventilation for the grow chamber.
Step 5: Air filter and ventilation for the grow chamber
First I picked up some heavy-duty chicken wire at the Depot. $5 for 2'x5'.
Next I used a little math to figure out how big to cut the chicken wire. I needed a cylinder that measured 2.5" and another one 3.5" to accommodate my setup. The formula is (PIE x diameter)=length of chicken wire.
Then I zip tied
Tested and made sure it fit which it does. Then I made the outer cylinder and tightened up the zip ties. Checked them out and it looks good. Useful Tip: use a closet rod or something similar to round out the chicken wire after you zip tie it. Wrapped them in some panty-hose to hold the activated carbon in place
I am going to use two of these fans. The intake is on the side and the exhaust is the rectangular part. I am going to attach the two opposite ends of the PVC to the intakes of the squirrel fans, sucking the air through the filter and exhausting out the box. Then I am going to use dryer hose and run the two exhausts to the attic via the ceiling. No one will notice due to the drop ceiling in my apartment.
I went to home depot and did some more shopping. I picked up some Caulk Saver to use as a spacer for the filter. It was about $5. I cut off a piece big enough to wrap all the way around the bottom to hold the center screen in place. It worked perfectly! Nice and snug too! Then I bought some activated carbon at Petsmart for $20.
I ended up only using a third of the carbon and filled most of the filter up leaving room for more spacers and the PVC joint. Then I capped it off and almost done. All I need now is to duct tape it to seal the ends and force the air through the middle to ensure it passes through the carbon.
Now I have the fans attached and will place them in the grow chamber where it will not disrupt the light from the top. I wanted to mount it along the side of the box to keep it low profile and prevent it from blocking the lights in any way
To install the air ventilation, first I cut the holes for the squirrel exhausts to fit into snuggly. The first hole is cut, and this one will be used as a reference for the next. The second hole was a little tricky. I had to hold the filter and fan together to find the right position, remove the filter and trace the exhaust, but it worked out in the end.
I decided to run the wires out the same holes to keep things neat inside. The squirrel fans will be wired like the computer fans, which were shown in steps earlier. The following picture shows the finished wiring jobs from the fans. The next step was to make all the holes in the box airtight with duct tape. Especially around the filter to prevent any unfiltered air from escaping the grow chamber. I also taped the inside just to be certain no air can escape without being filtered.
All the holes and wires air taped up and the wires are secured to the box.
Here, I didn't have to cut the end of the power supply that connects to the squirrel fans because I got it to work without having to. It saved me a little time and the hassle of using any connectors. To reduce the stress on the squirrel fans, I made this sling with zip ties to support the opposite end. A close up of the sling in action.
I just need to seal the PVC and the squirrel fans to make them air tight and its done as far as mounting them goes. I ended up mounting the squirrel fans too close together but it was an easy fix. I just sanded the PVC until it fit the way I wanted it too. I am also going to screw a piece of wood underneath the lower squirrel fan for a little extra needed support.
One very cool feature about this particular power supply with the selectable voltage, it acts as a variable speed control for the fans!
Step 6: Lighting in the Grow Chamber
After I got the wiring of the fans done and made them airtight, I installed some CFL's that are only going to be used for the early stages of growing. I picked up two cool socket splitters by mistake thinking they were the socket adapters for the outlets. Luckily I found a good use for them. I mounted two power strips on opposite sides of the box. I screwed extra screws to the sides of the box giving me the option of adjusting the height of the power strips later on if I need to. Here's the setup, A power strip - $3 Adapters - $2 each CFL's - $7 for two The finished product I do not have any specs on this final product, but each bulb is 100 watt The weight of the two lights looked like a bit too much for the socket adapter to handle given how it is mounted, so I used some zip ties to secure the lights and prevent them from falling out. Here is what the box looks like now. All I need is glass and intake holes for the grow chamber! I just added up all my receipts and had a grand total of $334.17 for the total money spent on the box. Here are the CFL's in action. As you can see, I used two bulbs of the higher spectrum up top and one of the lower spectrum just underneath to broaden the range of light. I could easily add more bulbs but this should be enough for the one or two plants I will be growing for the first two weeks before I kick on the HIDs.
Step 7: Puting it all together
The wiring was pretty simple for both the fans. I just connected the two wires from the RCA cable to the power supply. The particular power supply I used was two pronged and I used it solely to step down the electricity coming from the wall. The power supply has two leads as well just like the RCA cable. For the computer fans, I just cut the tip/connector from the power supply off which left me with two leads. I just attached the two leads from the fans to the power supply and that was it. The fans didn't spin when the wires were attached wrong so I tried the other way and it worked. Just make sure the fan is spinning the right direction before you seal up the connections with tape. With the squirrel fans, I managed to get them working without having to cut the tip off like I did with the computer fans. Since you're dealing with such low levels of electricity, there is plenty of room for trial and error. Just don't plug a fan directly into the wall. I used the caulk saver specifically as a flexible spacer. I am not using it as a liquid repellant and I just used duct tape to seal the ends. That was the easiest way to make the ends airtight, forcing the air to get sucked through the carbon. I actually have two power supplies powering two fans each. The computer fans use hardly any power at all. I have been considering using one power supply per squirrel fan but currently I have the two hooked up to one and that works too. I was considering using independent power supplies for the squirrel fans because they use up 10 more power (1.2 amps compared to .12 amps of the 'puter fans) than the computer fans and they don't seem to be running at full capacity. I made the platform about 6" short of reaching the back. Then I lined the area underneath with black plastic sheeting to help absorb light. On the right side of the box, I put strips of duct tape on the areas where I was going to staple the sheeting to the box to help reinforce it and prevent the plastic from tearing. It seems to work pretty well. I did the same on the left side but with screws so I can remove and replace the plastic when I want to take a look. I found a spare hook and did the same thing with the bottom center of the plastic sheeting that I did when I stapled the sheeting to the box. This allows me to remove the sheeting when I want and keeps the hole intact from opening it up everyday. With this ventilation modification, I keep the fan on low in front of the box and it blows air in the bottom, and up through the back inside. It works really well because when its all sealed up, the plastic poofs up a telling me that air is definitely being pushed inside. With the bottom lined with the black side of the plastic sheeting, it seems to prevent light from getting in while allowing air to get in. This hardware store down the street from me at the time cut custom pieces of glass. Just told them what size and they had it a couple days later. I believe both pieces were 1/8" thick and non-tempered (cheaper) and it did the job. The size I got cost me just under $20 a piece. With this basic construction of this box, making any adjustments or adding any items would very easy to install.