It's no secret that I like to build self watering containers from various things, because they allow me to put my own signature on some of the many designs already on the internet - and it's fun, too! With any good weather conditions at all on the weekends, i'm usually outside for at least 8 hours each day tending to things and building stuff of course. It's just what I do, because I just don't watch much television. Anyway, i've been getting several swc's ready for other people as of late, because it won't be long before they'll be needing them to grow tomatoes in. Here's my take on constructing a swc from an 18 gallon tote.....
When possible, I like to construct the entire thing with only one container, because it's much cheaper that way. Also, since you get a lid with the tote anyway - why not use it to its fullest potential? For this project, i'll be cutting the lid into several pieces that will be used to suspend the growing medium above the water reservoir, and also to keep the sides from bulging outward when filled with soil. Construction time may be a little bit long for most people's liking, but I just take my time - while enjoying the opportunity to be outside with the birds singing in the background. Of course I take a few timeouts along the way too, because Jude just has to meet her quota of catching the frisbee at least 50 times. Gosh, that dog sure loves that thing.....Anyway, back to the swc. If you'll follow this construction method, the end result will be worth the effort, I promise.
The perforated barrier that the soil mass rests on is cut out from the lid, and several yogurt cups are attached to it by using cable ties. Getting it cut to a perfect fit is kinda tricky, but I always just set the tote on top of it, and draw a line around the bottom with a sharpie pen. Because the tote gets wider as it goes up, the initial cutout will always need to be bigger - but I just add about an inch all the way around when cutting the pattern out with some tin snips. It can be trimmed to fit perfectly later, so no biggie.... Anyway, the little cups are very effective at supporting alot of weight, and you wanna space them out as shown below.
Photo below - I always cut a notch in each as the picture shows, which allows water from the reservoir to pass freely in and out of it. This way, the space inside the cups is utilized for extra water holding capacity, and it doesn't effect the cup's rigidness. Notice that the cuts are made toward the middle of the barrier. This is because any soil that actually makes it into the reservoir will most likely enter around the outside edges, and might clog the holes in the cups, if not pointed away from the sides.
Photo below - The perforated barrier is then lowered into the tote, and checked for fit. Keep trimming the edges until it fits snugly into the bottom - making sure it rests totally on the cups. This takes several attempts to get it right, and always remove just a little at a time.
Now for the fill pipe. This is a 16" long piece of 1-1/2" pvc pipe. Four holes are drilled into one end with a 5/16" drill bit, which will allow water to enter the reservoir as it is filled with water.
Photo below - See this little fella? It's a foam ball that can be found in the arts and crafts dept. at Walmart, with a 16" long, 1/8" wooden dowel rod stuck into it. I just purchase the 4ft. long sticks at Lowes for 48 cents each, which means you can get three out of one stick. Really cheap, and lightweight, too. Anyway, this will be used as a water level indicator.
Photo below - I wanted to show this picture of the perfect fit for the foam ball into the fill pipe.
Photo below - set the tote onto a level surface, then lower the homemade indicator into the pipe. With the ball completely at the bottom, make a mark around the stick where it meets the top of the fill pipe. This is the reference for "empty", and really all you have to indicate. As the reservoir is filled later, the ball will float upward inside the pipe.
Photo below - Now, I cut some pieces from the perimeter of the lid, and attach them to the four sides as shown in the picture. With the perforated barrier and side pieces in place, you can see that there's not much room at the sides for soil to fall down into the water reservoir later. That's a good thing, and the addition of landscaping fabric on top will only make it even better. Self tapping screws are installed through each from the outside, which will keep the sides/ends from bowing out as the soil is added later.
Photo below - here's the landscaping fabric in place, and you're gonna want to curl the edges up the sides as shown. When filling with the growing medium of your choice, take care to put down the mix around the sides first - which will keep the curled edges in place while filling the remainder of it...
Photo below - I always like to determine what the water holding capacity of the reservoir is, which will also tell me how much soil mass the plants have to grow in. That's what's most important - how much soil is available for the plant roots. Anyway, this one has a water holding capacity of 2.3 gallons, which leaves room for about 16 gallons of soil mix for the plants. To find where the 5/16" drain hole should be drilled, I simply point the end to be drilled away from the direction of the sunlight. This causes a shadow where the perforated barrier is, and the hole is drilled about a half inch below the top part of the shadow.
Photo below - As you can see, i've built quite a few already, and (might) do a couple more if I run out of things to do around here. I've also got an old 34 gallon tote bin that might see some action, because I bet 3 tomato plants could be grown in that baby....hmm...decisions, decisions....
Anyway, I just wanted to show my way of constructing a swc from a single 18 gallon tote bin, and hope you find the information useful. In only 4 weeks, these swc's will hopefully be put into action by their new owners.
Take care, and happy gardening!