DIY Geometric Concrete Planter Pots Using a Silicone Mold

This post shares how to make a DIY geometric concrete planter pot using a silicone concrete planter mold.

DIY geometric concrete planter pot

Today I’m sharing my project for DIY at Home this month—the theme is $20 DIY decor. And it’s a project that originally started as a DIY fail. What was the fail, you asked? Well, I’m working on an upcoming post about how to use a heat gun to pop air bubbles in resin. For that post I am making epoxy resin planters.

I’d originally purchased the silicone planter mold I’m using in this tutorial for that project. However, I didn’t realize the mold was a matte silicone when I ordered it online, so it made the normally shiny resin look dull once it cured. And a little bumpy. Yuck.

Determined not to waste even a few bucks on a silicone mold, I decided to try it out with concrete. I love working with concrete and even made some cute little concrete planters a few years ago, as well as some chic concrete coasters, and some concrete candlestick holders. And I already had a little box of concrete powder in my garage—the kind you just need to add water to.

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Rapid Set Cement All (Concrete) Mix
Geometric silicone mold
Disposable cup and stirrer
Water

And here’s how I made my DIY geometric concrete planter pot.

Step 1: Mix the concrete

First I mixed my concrete. I mixed it in an old tumbler Mike was throwing out, so I wanted to give it one last chance to be useful in life. You can just use a plastic cup if you’d like. The ratio for my concrete was 4:1 powder:water. I usually tweak this a bit.

I added just a tad more water to this mixture to get that nice wet sand consistency. If the mixture is too firm, it won’t fill all of the crevices of the mold. I didn’t worry too much about mixing up more concrete than I needed because it’s so cheap.

I didn’t mind throwing the extra away, but I definitely didn’t want to not have enough. What’s that they say about being better safe than sorry? That’s my motto with concrete, especially because it sets so quickly.

If you jump the gun and add too much water, you can always add in a bit more powder and stir until you get the perfect consistency. Don’t dilly-dally, though. Concrete sets fast! Also, don’t fret if stirring is a bit difficult. I used a paint stirrer instead of a smaller popsicle stick so I could really man-handle it. Once it’s sufficiently mixed, stirring will be a breeze.

mixing concrete to a wet sand consistency

Step 2: Fill the silicone concrete planter mold

I did not grease the mold, but you can if you’d like. A kitchen oil spray will work fine. For what it’s worth, my molds all came out fine, and I made three.

Immediately after mixing the concrete (do not wait!), pour it into the mold. Fill the mold about halfway full and then quickly tap around the sides using your stirring stick. This will help “shake” the concrete down into all of the crevices. It’s another reason the paint stirrer is great. A popsicle stick might not have had enough force. Then immediately fill the rest of the mold.

Once the mold is totally full, use your stirrer to again tap in quick succession all the way around the mold. Do not skip this step. It forces the air bubbles to the surface so they can pop. This helps the concrete settle while drying and gives the finished piece a much smoother look. Use the stirrer to skim excess concrete off the top for an even base. See the video in this post for this step in action.

Okay, I know I said not to skip the tapping step, but that if you want a more rustic, industrial look to your concrete, you can skip the tapping step. You’ll just have bubbles in your finished product, which sometimes is kind of cool.

Step 3: Let dry, pop out, and sand

Let everything dry for a few hours. When it feels dry and hard to the touch on top, give it another hour or so. The bottom are (which is actually the top once the project is finished) could still be fragile and could break when you pop it out.

Once you’re confident it’s dry, simply pop the planter out and admire its beauty. If necessary, polish up any rough spots around the base with a very fine-grit sandpaper.