How to make Self-Watering Planters

Here I’ll show you step-by-step how I make my awesome self-watering planters out of 20 gallon plastic storage bins.

One of the best things I ever learned, whether gardening indoors or out, is the value of self-watering containers. I still remember the summer I first converted all of my flower boxes to self-watering. It was so much work, but then the plants just started thriving. We couldn’t believe the amount of growth exploding out of the flower boxes.

A self-watering container simply means that there is a reservoir of water at the base of the container, and a wicking medium which allows water to travel up to the soil. This way, the plant roots aren’t sitting in water suffocating but they can still access just the right amount of water they need.

With this system, you can water much less frequently because there is a large storage reservoir of water. You can turn almost any container in to a self-watering container, but I find these nice 20 gallon bins make for an ultra-efficient gardening space. It can then be used in your indoor tub-top garden (like mine), in hard-to-reach flower boxes, or out on your patio or deck all summer for some mighty fine harvests! Let’s get started!

This is a drawing in color, of how to make a self-watering planter including a cross section of what the planter looks like in action.
Here’s the overall idea…

Items you’ll need:

  • 20 gallon bins with lid.*
  • Section of pipe or tubing approx. 24″ long. Bamboo or copper pipe would be best but I used 1/2″ irrigation drip pipe for mine because it is much cheaper and we have it lying around.
  • At least 2 large plastic containers (such as re-used 32 oz yogurt containers)
  • At least 4 smaller plastic containers (such as re-used single serving yogurt containers)
  • 1 bag (1 cubic foot) of any garden or potting soil like this, especially for raised beds. These go on sale pretty big-time in the fall so you can stock up.
  • 1/2 bag 8 Qt bag of Vermiculite.
  • Weed barrier fabric cut to about 2′ x 3′.
  • Drain sleeve, or really any fabric, cut to about 12″ x 12″.

Tools:

*To help keep things looking tidy, try to pick one container size and stick to one color if you can. You can buy 20 gallon storage containers at any big department or dollar store. However, they usually go on sale right after Christmas at Walmart and you can pick them up for 4$ a piece! Otherwise they’ll run you about 6-8$. You don’t need anything fancy, just make sure you grab the lids too. We’ll use those…

Tools and items you’ll need

Step 1. Mark your reservoir height.

First, measure the height of your smaller plastic reusable containers. Ideally you want them to be between and 4-6″ high. (They will eventually hold up the reservoir floor, so their height determines the reservoir’s depth.) Mine were 5″ high, so I marked at 5″ above the base of the bin on all four sides with chalk. As you can see, this leaves me about 9″ of growing depth for nice long carrot roots!

This shows measuring a 5" depth with chalk on the bottom of the bin.

Step 2. Measure the width and length of the bin, at your determined reservoir height.

Step 3. Cut the lid of your bin, so that it forms the reservoir.

Here is where you need either a box cutter or the heavy duty scissors. Normal scissors will make this a painful job, heavy scissors make it a snap. First mark out your measurements. I used a different color bin lid so that it stands out for pictures, but normally, just use the lid that came with the bin!

Step 4. Cut out the holes for your “wicking pots”, ie. the larger plastic containers.

Trace around your larger plastic containers, here they are reused 32 oz. yogurt containers. Drill a hole in the center to get you started, then cut out the hole using the heavy scissors or a box cutter. Don’t worry if it doesn’t look pretty or isn’t exact.

Step 5. Drill holes in your wicking pots, to make them become wicking pots.

What is a wicking pot? It is basically any medium that allows water to travel from a place where there is water (ie. your reservoir) to a place where there isn’t water (the soil of your container). It is important that the wicking pot is full of soil, with no air holes to prevent water movement. And you need plenty of water to get in to your wicking pot. So, you’ll need to drill lots of holes in the larger plastic containers. This will allow the water to seep from the reservoir, into the soil in those containers, and then to be “wicked up” into the rest of the soil in the bin. You can also buy wicking pots if you feel like skipping this step, but isn’t this a great way to reuse some old plastic containers? Just be careful with the drill…The first time I tried this, I didn’t secure the containers and they spun away violently like little UFO’s! So, this is the way I suggest, to do it more safely. Get a block of scrap wood that will fit into your yogurt container. Stick it in the container to give yourself a steady base. Drill your holes. Turn the container, repeat.

This shows the drill set to the drill setting.
Don’t forget to set your drill to the “drill” setting. Works better.
A close up of the wicking pot with holes.
The “wicking pot”!

Step 6. Create a hole for your watering tube.

The point of this hole is to allow passage of a tube to get water into the reservoir. Figure out where you want the hole, drill a starter hole. Use your heavy scissors to make it the right size, stick your pipe through it!

Step 7. Assemble your bin.

Place your small reusable plastic containers in the bin to help hold up the lid, then plop your modified lid into the bin, with the larger containers in place.

This shows the bin with the false bottom in green, two "wicking pots" ready to be filled, and a tube where the water will be added.
Assemble the unit…it’s ok if there are some holes and leaks. We’ll fix those.

Step 8. Fill the holes where dirt might fall.

I use Drain Sleeve over the yogurt pots/wicking pots. I like them to have the best chance to absorb water but still keep dirt from falling through into the reservoir. The Drain Sleeve really coats them nicely while still allowing great water flow. Then I cut the weed stop fabric to place over the entire new “floor” of the bin. That way very little soil gets down in to the water reservoir.

Step 9. Fill the wicking pots with soil heavy in vermiculite, and pack it in good.

The wicking pots cannot have any air holes in them or that will disrupt the wicking properties of the soil. Mix garden soil and vermiculite almost 1/2 to 1/2, then fill the wicking pots and press the soil down firmly. Then, fill the rest of the tub with normal soil (with only about 1/6 vermiculite mixed in).

Step 10. Drill the “overflow” hole. Don’t neglect this step!!!

The last thing is to measure your reservoir depth (ours in this example was 5″) on the outside of the bin. This is the line where the water reservoir ends and the soil begins. Your roots are potentially just above this line and you never want them to be in standing water – that can suffocate them. So, you drill a good-sized hole here to make sure that if you fill the water reservoir all the way, the extra water will spill out, and therefore never leave your roots in standing water. This final step makes these the perfect little planters for your crops!!

Now you can add some amendments like a handful or two or organic bone meal, and start planting!! Enjoy!

Your “raised” garden bed, ready to go!

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How to make your own self-watering planter out of a 20 gallon storage bin. TubtoTable.com

Turn a 20 gal plastic storage bin into an awesome self-watering planter!

Tools & Supplies

  • 20 gallon bins with lid

  • Section of pipe or tubing approx. 24″ long

  • At least 2 large plastic containers

  • At least 4 smaller plastic containers

  • 1 bag (1 cubic foot) of any garden or potting soil

  • 1/2 bag 8 Qt bag of Vermiculite.

  • Weed barrier fabric cut to about 2′ x 3′.

  • Drain sleeve cut to about 12″ x 12″.

  • Tools
  • Drill with 3/8″ drill bit

  • Heavy Duty Scissors

Directions

  • Mark the reservoir height,
    ideally between and 4-6″ high.
  • Measure the width and length of the bin at that reservoir height.
  • Measure and then cut the lid of the bin to fit.
  • Trace and then cut the holes for the larger plastic containers (the “wicking pots”).
  • Drill holes in the wicking pots.
  • Create a hole for the watering tube.
  • Assemble the bin, placing the smaller plastic containers under the reservoir lid to help support it.
  • Fill in the holes where dirt might fall with landscape weed fabric or drain sleeve or both.
  • Fill the wicking pots with tightly packed soil + vermiculite.
  • Fill the remainder of the bin with soil. Add amendments as needed.
  • Measure the height of the reservoir on the outside of the bin.
  • Drill a drainage hole just under the line.

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