Build Your Own Self-Watering Containers/Earth Box DIY

If you don’t have a lot of space to garden, you don’t have a lot of energy to garden, you don’t have the time to water daily, or you just want to add some plants right outside your kitchen door for convenience, then you might want to consider container gardening. In my last home, my garden was almost exclusively in containers. I’ve grown everything from lettuce and herbs, to tomatoes and pumpkins, and even carrots and radishes in containers.

I recommend Ed C. Smith’s container gardening books on what plants to grow in which sort of container. He says that even though he grows crops on acreage, he always keeps a container garden close to his door.

Here’s some good news: Rather than spending $60 or more/unit on commercial self-watering containers, I was able to make 5 containers that each held 2 full-size, indeterminate tomato plants for right around $60, including the fertilizer. (I also grew 2 very successful pumpkin plants out of one of my containers.) While some flowers and veggies are not happy with consistent moisture, and herbs fair (and taste) far better when they are allowed to dry out between waterings, most veggies grow bountiful in self-watering containers. My tomatoes thrived.

Here’s one corner of my container garden in standard pots (not self-watering). I’ve got chives, lemon thyme (amazing on chicken!), lemon balm (great as a tea for an upset stomach), and petunias. The big leaves camouflaging the pots are squash leaves.

Here’s another cluster of pots that I had right outside the door. You can’t see them all, but in addition to the flowers, I have parsley, basil, mint, and oregano.

The required parts for one self-watering container:

2- 18 gallon plastic totes– They don’t have to be exactly that size, but close is good. Get the lids.
1- 20″ or so of  food grade tubing–I found some at Home Depot. You want it to be about 5-6″ taller than your tote.
1- 5″ or so pond basket. I couldn’t find any in the water feature section of Home Depot, but I did find some pond lilies in baskets. It was late in the season, so they were on sale for $1 apiece. I discarded the flowers and used the baskets.

Required Tools:

Really good, heavy duty scissors. We didn’t have luck with a hand saw or our cheap electric saw. The scissors worked best.
Pen or marker for marking measurements

Here are the parts, unassembled.

I built these back in 2008, and had checked many sources before building them. Most of my tips, and my main directions came from I’ll share the basics directions here, but he goes far more into depth. I used Ed Smith’s guide for the potting mix, and the Earth Box’s plant and fertilizer placement guide.

Here’s what the box looks like assembled, before adding the soil mix.

Building the Box:

1. Measure from the bottom of “tote A” the height of your pond basket, and draw a cutting line all the way around the tote. (The pond basket is the black square basket with holes in it in my first picture of the parts. Yours may look different.) Mine was 5″, so I had a line 5″ high going all the way around my first tote (“tote A”). Cut all the way along your line. Discard the top part (the part that’s open on both sides) of the tote. You can plant potatoes or something in it later.

2. Still working with “tote A”, trace the top of your pond basket onto the center of your now cut piece (the bottom half) of the tote. (You’ll see the square cut out of the tote in the first 2 pictures of the parts. Yours may be a different shape.) Cut that piece out.

3. Also trace the top of the food grade tube onto the top of “tote A” in one of the corners, and cut out the hole. Make sure the tube fits tight.

4. Drill lots of holes into the top of the same piece of “tote A”.

5. Place the pond basket into “tote B”, and then place “tote A” into “tote B” over the pond basket. Make sure the pond basket is centered before pressing down tightly in the center and all corners.

6. Drill a hole into the side (or front) of “tote B”, just below the top of “tote A”, making sure it goes through both totes. For instance, if “tote A” is now only 5″ tall, then measure about 4.75″ up from the bottom of “tote B” and drill the hole there. This is your drainage hole that will prevent you from overfilling the tank you have created at the bottom of your container. It will also tell you when your tank is full so you don’t have to guess. About a 1/4″ hole should do. Make it no bigger than 1/2″. I don’t have a picture of this hole, but if you refer to the directions link I gave you, there is a picture there.

7. Cut all but the rim away from one of the lids. (See the last pic of the final product, with the plants.)

The soil mix is half high quality potting soil from a local nursery (it’s Family Tree for the KC folks), and half compost, mixed together.

Filling the containers:

You can find many tips on what works inside the container. I used a combination of Ed Smith’s tips, and the Earth Box planting guide. Here’s the formula, though I can’t tell you exactly how much it took. I just kind of eyeballed it, though you could be mathematical about it and figure out how many cubic feet your container will hold.

1 part organic potting mix
1 part compost
3 cups of organic fruit and vegetable fertilizer

Mix the compost and potting mix together, but do not mix in the fertilizer. The fertilizer will go in a strip at the front or center of your container, depending on what you plant. It’s all in the Earth Box’s plant and fertilizer placement guide.

And here we are with the baby tomato plants.

I wish, I wish, I wish I’d taken a picture of the tomato plants fully grown. I can’t believe I didn’t. I used 6′ fence posts, and trellised them. They grew all the way up, and then a couple of feet down the trellises.

I did, however get a pic of a typical summer day’s harvest.

And here’s one of the squash blossoms from a pumpkin plant. You can see the self-watering container in the background. We got about 6 sugar pumpkins/plant! These I did not trellis, because they were “bush variety”. Yeah right! They ended up growing all over the patio!

Do you have a container garden? If I’ve inspired you to start one, be sure to let me know! If you’re in the States, it’s not too late to get started! If you blog about it, feel free to post links in the comments.

Edited to Add: Charlie, I’ll loan you my book. He addresses converting a regular, decorative pot into an SWC. ~Daniél


5 thoughts on “Build Your Own Self-Watering Containers/Earth Box DIY

    • That’s a good question. I suppose it’s not necessary. Some people use pvc. There were so many different piping options, and I had no idea what sorts of chemicals were in each one, so I decided to go for the food grade.


  1. Is it possible to get food grade plastic totes? Or, if I really want to do organic gardening, should I just buy the ones from Earthbox? Or make them out of wood with the water section line with food grade plastic?

    • You know, I’m not sure about that. I would ask at Home Depot, or a garden center. The same technique can be used with food grade buckets, so if you can get your hands on some of those at a reasonable cost, that would be another way to do it. Making them out of wood, or lining the totes with food grade plastic sounds like a great option! I gave all of mine away when we moved recently, and plan to make more. I think I am going to look into this as well.

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