How to make DIY concrete planters in geometric shapes using a cardboard mold.
Hey, Brent here! Today I am sharing these geometric concrete planters I made this past weekend using cardboard molds. You may have noticed things were a little slow around the blog last week. That is because Courtney and I spent the past week in San Francisco! We had a great time exploring the city.
Unfortunately, Courtney caught a cold on the way back home so while she was resting this weekend I took it upon myself to start a new project that was inexpensive and quick to put together (if you don’t count waiting for the concrete to dry).
I had fun experimenting and making these DIY concrete planters to display around the house.
How To Make DIY Concrete Planters
- Cardboard (I used a moving box)
- Clear Packaging Tape
- Quikrete Crack Resistant Pro Finish Concrete Mix
- Plastic bucket
- Box Cutter
- All-Purpose Mixer (attached to a drill)
- Electric sander
FREE TEMPLATE DOWNLOAD
Want to make this diy project? Download Our Free Concrete Planter Template
How to Build the Outside Mold
1. The first thing I did was measure and trace seven triangles on cardboard and then cut out each individual cardboard triangle with the box cutter. At the end of this post I have included a PDF of the pattern I created for our geometric concrete planters to download if you are interested in making your own.
2. I cut out seven triangles of equal size and then arranged them into the pattern above.
3. Next, I taped the inside seams of the triangles together.
4. Once the box was taped on the inside and assembled into the three dimensional form, I added tape to the outside to strengthen the mold.
How to Build the Inside Mold
5. To create the inside mold, I cut out two more triangles and three squares.
6. I assembled these pieces and covered all the seams in tape to create the three dimensional form.
How to Mix the Concrete
7. First, I prepped my materials which included the bucket, water and the concrete mix. I made sure to have twice as much water than needed on hand.
8. Then I poured the water into the bucket and mixed in the concrete mix with the mixer attached to a drill. I continue to add the dry concrete mix into the bucket until the mixture was thick and evenly mixed with the water. To test for the right consistency, I dug a little hole in the mixture. When the mixture didn’t fill in the gap, I knew it was ready to use.
9. Once the concrete mixture was ready, I filled the bottom of the outer mold. Then I placed the inner mold into the outer mold. The inner mold acts as a plug and creates the hole in the planter for the plant.
10. When you mix concrete it traps air bubbles inside of it so after I poured the concrete into the mold I used an electric sander to vibrate the concrete forcing the air bubbles out which gave me a smooth finish.
11. I let the concrete sit in the mold for several hours and then I removed it from the cardboard. I found that depending how long you leave the concrete in the mold, you get different textures on the concrete which I like because it makes each planter unique.
12. You can see the difference in the photo above. For the planter on the left I let the concrete dry in the mold for approximately 18 hours which gave me a smoother texture. The planter on the right was the first one I made and I only let it dry in the mold for around 3 hours which gave me a rough cinderblock like texture.
I planted succulents in them and placed them on the nightstand in our bedroom. These were so easy, inexpensive and fun to make that I am sure I will be making many more to add throughout the house.