Earthtrainers. He uses two containers to make one self watering grow box. My modification does the same thing, but it doesn't destroy one container by cutting it in half and wedging it into the bottom of the other container. I just cut two wick holes out of the bottom of one, attach two pond filter baskets to the holes, and set that inside the other container. This gives double the space for soil and water capacity, and doesn't completely destroy any containers. I'll post more detailed plans if someone wants them. A 32 gallon grow container costs $25 to build. It's getting pretty late to start though.
I'd be interested in that. One could definitely put some later growing crops in one.
The stuff you need is in bold. The instructions are in green below, if you want to skip right to them.I may not have accounted for every possible issue with these things, but they are performing nicely so far. The above mention of mold made me think that could be an issue with young plants barely using the water, which is sitting in the bottom now going on two weeks. The $25 does not include soil, and you can accessorize with after market products as much as you want. Mine are in the Mojave so they are wrapped in reflective windshield protectors to keep the soil from overheating. I'm thinking of rigging a toilet float in the reservoirs so they automatically refill to three inches.
The basic grow box requires the following items to construct:
Two containers, 30-32 gallons preferable.
Something like these basic ones is fine. Rubbermaid costs more but supposedly has better UV protection. Which didn't matter to me because I wrapped mine for extreme heat conditions.
I bought 12 32g units @ 8.99 ea @ Kmart to make six grow boxes.
Two 8 or 9 inch pond filter baskets (plant baskets)
Home Depot had these for 1.99 each.
I used the square 9 inchers, but the smaller ones would be fine. I was a little over concerned about water usage in the desert and these baskets provide the space/size of the reservoir. So I went bigger.
A drill.
I used a cordless hammer drill and a wood screw for the bit.
A way to cut the plastic.
I used a circular saw, carefully. A strong carpet razor cuts through with two passes, score it deeply once then got over it and you're through with a little tapping.
8 plastic ties or some heavy gauge galvanized wire.
I used wire because it was on hand. The Earthtrainer instructions use plastic ties. You can get a package of 20 8" ties that will do the job for 2.99 at Ace.
You're at $24.95 before tax.
And that's all you need.
I bought the 12 containers planning on following the Earthtrainer pdf instructions. I cut off the bottom portion of the first container (a hassle) as instructed and stared at the whole project for about an hour with my little wheels spinning. I've grown hydroponically for a decade, never in containers like this but with similar concepts, and I had issues with those instructions. I was also feeling a little lazy and unhappy with the fit of my particular containers. They are all shaped a little differently and mine did not do what his did when I inverted and wedged the cut off bottom into the other container. So I put the cut up one to a different job (growing exotic mushrooms in donkey dung) and got a replacement for hopefully a better, much simpler idea. I'll explain why I think so after the instructions.
Anyone (especially you Earthbox people) -- feel free to question and troubleshoot these if you're following along and see an issue.
Instructions:
Inner Container
The bottoms of my containers were exactly 24" long and 13" wide. With a crayon I divided the bottoms into two 12X13 halves. I then drew 3.5" squares
in the center of each half and cut them out. The exact math will differ per container sizes, but it's simple enough to figure out. These holes are for wicking moisture from the reservoir to the soil. So...
You have to attach a basket to each hole on the
outside bottom of the container. The container should stand raised and level on the attached baskets. Centering each basket over a hole, drill four holes in each corner through the basket edge and through the bottom of the container. I taped the baskets centered to the bottom holes to keep things lined up as I drilled the mounting holes.
Since I used wire run through the holes and twist tightened, I drilled the holes in opposing corners and used one long wire for each basket, fed up through one hole down through the next until they met at the first hole -- tightened it up and snipped the ends. This was fast, simple and really strong when tested. So I drilled a total of 8 holes, four per basket.
If using plastic ties, you drill two holes in each corner an inch or so apart and cinch tighten four ties to each basket. That's sixteen total holes, 8 per basket. It's more work and probably not as strong.
The inner container is now complete. It will be set inside the outer container.
Outer Container
Real easy. My wick baskets are 6" tall. You want a pocket of air between the water level and the soil. So decide where you're going to add water to the outer container (the rim is exposed from the inner container being lifted so you can water where you please all the way around). Measure 4" from the bottom below the fill site and drill a hole. You could just drill a small hole, but I drilled a half inch one that I can close with wine cork. When you add water it will drain out of this hole when "full" thereby providing a two inch pocket of air.
The outer container is now complete.
Set the inner container inside it. The grow box is complete and only needs sunshine, the potting soil, mulch, and plants of your choice, and water.
Some pros to the modification:
Really quick and easy to construct.
As mentioned, cleaned up, baskets removed and with a cardboard liner in the bottom of the inner containers, all containers can be taken down and stacked in storage or used as actual storage containers if wanted, so save the lids.
If you put a flashlight on most of these type of containers, you'll see some light get through. This is bad for things like algae and mold and some other nasty possibilities. Stack one container on top of the other and hit it with the same light and none gets through. So my method blocks more light than the Earthtrainer method. It's not perfect as the reservoir has only one wall, but it is improved, and mine are blacked out by the wrap I mentioned.
Earthtrainers and Earthboxes both hold about 14 gallons of soil, and about 3 gallons of water. My modification allows for six gallons of water, double the reservoir space, a bigger air gap (more oxygen to the roots) and 32 gallons, more than double the space for soil. Professional growers will tell you anything under 10 gallons per normal tomato plant will stunt the plants and lead to root rot destroying late season yield. The other two have 7 gallons each for two tomatoes, mine has 16 each, allowing for much healthier plants. I could and am growing three heirlooms in one container having just over 10 gallons of root space per plant. One common complaint in one forum on topic is how often they need watering.
These haven't used their initial 6 gallons of water in two weeks time. The tomatoes are happy, the soil staying evenly moist through very hot dry days. I used a homemade potting mix that is mostly sterilized leaf compost (60%), some bark (15%), perlite (15%) and a heathy dose of fully composted sterilized horse manure (10%). I also sprinkled a little time release fertilizer on the top and worked it in the top two inches.
As an experiment, on two of them I laid landscape fabric deep inside the inner containers just over the top of the compost filled baskets to prevent roots from getting into them. On two others I wrapped the fabric around the outside of the baskets to keep compost particles from getting into the reservoir. On one I did both; on another I just filled the baskets with potting soil along with the containers. They all seem the same so far.
My intention was to mimic a successful desert test garden and use reflective mulch, but the way these things are conserving water, so far, no mulch. I may drill drain holes in the very bottom to empty the reservoir. That water has to be pretty stinky by now. I just haven't decided if it's necessary and if the cork method is safe or how to seal them while put together.
Another feature is that it is possible early in the season to lift the inner container out of the outer container and drain everything. My guess is that sucker weighed about 120, so prepare to hoist. But this could come in handy for a variety of reason other than just draining. The oxygen charge alone should be great for the young plants.
I'm tired. GL
