How to make concrete planters and everything you need to know for making planters at home.
Ready to get started making concrete planters? You’ve come to the right place.
Whether you are a seasoned concrete planter-making pro or a first timer, this everything guide for making concrete planters is filled with lots of information that I hope you find incredibly useful.
By the way, all this information applies to making cement planters, you make a cement planter the same way as concrete planter, the mix just may be slightly different. Here’s an article explaining the differences between the two.
Pocket Guide to Concrete & Cement Mixes For Crafts
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Materials Needed For Making Concrete Planters
- Cement, rapid set
- Disposable bowl
- Disposable cup
- Durable nitrile gloves– I like these because they are so durable, you can rinse and reuse
- Safety glasses
- Safety mask– rated for silica dust
- Drinking straw- for the drainage hole
- Hot glue
- plastic bottles, plastic buckets, plastic containers
- Utility knife
*For details about handling concrete safely, take a look here.
The Type Of Mix Used For Making Cement Planters
Most any concrete or cement mix can be used for making planters. But the best cement for making pots will depend on what you are using as the mold, as well as the size of the planter.
I find Cement All to be the best mix for cement planters because it sets quickly and cures in about an hour.
I also like it because it’s one of the smoothest concrete mixes for planters.
The easiest way to get a planter smooth is by using a smooth mix.
Portland cement is another good cement mix for DIY planters. But you must add sand to it, otherwise, it won’t bind.
Using a smooth cement mix to achieve smoothness in a planter is important. But also keep in mind that you must also make sure to mix the cement or concrete so that there are no lumps.
You will also need to vibrate the wet mix after you have cast your planter.
If you don’t vibrate the mix, you will end up with either pin holes or pock marks (air gap holes).
Another consideration in choosing a concrete mix is color. Some concrete mixes are white, some are grey from very light grey to a fairly dark grey. And some mixes are off-white or even beige.
If you are making a planter and are coloring the mix, then I recommend using a white cement. The whiter the mix, the purer a color you can achieve.
Safety When Handling Concrete For Making Planters
Concrete is a caustic material and needs to be handled with gloves, especially when the mix is wet.
Even the dry mix powder can burn you. Be sure to protect your skin with very durable nitrile gloves when handling concrete and cement.
A thicker glove will help prevent tearing.
Another danger to working with concrete is that the dry mix dust is harmful to your eyes.
Concrete also contains silica which can actually cause cancer with repeated exposure.
Mixing Cement For A Planter
A typical cement pots recipe is two cups of concrete or cement and about half a cup of water. This is the proper ratio for many mixes- if you are making a small planter.
Some mixes require the addition of sand, but most do not. If you are using Portland cement, then your cement to sand ratio should be either 3:1 or 2:1. You can get full details about the what’s the best cement mix ratio in this article.
For larger planters, you will need to increase the cement to sand ratio.
If you are casting a planter with narrow walls, then you will need to mix the concrete to a consistency of a thick milkshake.
This consistency is helpful so that you can pour it in and so that it will get into the grooves. For other types of planters, you will want an apple sauce-like consistency.
The Thickness Of Concrete Planters For Durability
The thickness of a planter needs to be a minimum of ⅜” thick. However, ultimately will be determined by its overall size. The larger the planter, the thicker the wall should be.
A small planter can have walls and a bottom as narrow as ¼” thick.
A concrete pot that is 10x10x10” will do better at a thickness of ⅜” to ½”. And larger than that should be even thicker.
Making A Concrete Planter Mold
Making a concrete planter mold is quite simple.
You can make a mold for a concrete planter by making your own silicone mold, or building a form with wood, or building a form with corrugated plastic.
For larger planters, use wood. Some people like to build plywood forms. I prefer using melamine since it has a smooth surface, which makes the concrete smooth and easier to demold.
The method you choose will depend on the size and shape of the concrete planter that you intend on making.
You can also utilize other materials for making concrete molds. This article discusses all the methods for making concrete molds for crafts.
And this article will tell you how to get your concrete shiny and how to get it matte.
Reusing Existing Items As Molds For Cement DIY Projects
I also discuss this in great detail in my article about choosing the best mold types for your concrete projects.
But the short and quick of it is that you can reuse any plastic container that is straight or slightly beveled.
Different shapes are possible, but keep in mind that if the container has a bevel that goes in and out again, that is called an undercut.
An undercut will make it difficult to remove the cured concrete from the mold. The more simple the form, the better.
Creating Drainage Holes For A Pot Made From Concrete
Cement and concrete planters need drainage holes, even though concrete and cement are porous materials.
You will need a way for water to escape and will need to create a drainage hole.
I much prefer to create a mold for the planter’s drainage hole, rather than have to drill it after the fact.
The size drainage hole you need for a concrete planter will depend on the size of the planter. For very small planters, one ¼” hole should suffice.
For larger planters (7×7”) I may go up to three holes for drainage.
If the planter is very large, like about a foot or more, then either create additional drainage holes. Or make larger drainage holes using a jumbo sized drinking straw.
It’s much easier to make drainage holes during the molding process, rather than having to drill them after the concrete has cured.
So how do you make mold with a drainage hole? First, take a drinking straw and cut it to about 1/4″. This is because it will need to be the thickness of the bottom of the planter.
Next, use hot glue to glue it to the bottom of the mold and fill in the open end of the straw with glue.
To drill drainage holes in concrete planters, use a power drill with a diamond head drill bit and use water while drilling.
Hint: I’ve seen PVC pipe used for drainage holes in concrete planters, but in my experience these have been extremely difficult to remove.
You’re better off filling a plastic bottle with sand to make an open tube and using that. You’ll be able to easily remove it.
You can see a variation of the sand/tube drainage method used here, but in this instance it was used as an interior form.
If you are looking for plants that are great for pots during winter, you can read about those here.
Curing Cement Pots
The length of time you cure concrete planters is going to depend on the mix you are using and size of the planter.
The majority of concrete and cement mixes will take about one day to cure, and then several more days to dry.
These times are a general guide because a tiny cement craft will cure in less time than 24 hours.
However, a large concrete planter box with walls 2” thick, may take longer than 24 hours.
Many brands make a concrete mix that sets quickly. Some quick setting mixes will cure in about an hour.
There can also be mixes that are rapid setting, but not necessarily quick curing and can still take a day to cure.
The reason for having a mix that sets quickly is because some projects do better if their setting time is shortened- like this Cement Balloon Planter.
Wet Curing Concrete Planters
It’s important to note that some concrete mixes for planters require a ‘wet cure’.
Wet curing is simply keeping the cement and concrete moist during the curing process.
The way to wet cure concrete is to mist it with water and then wrap it with plastic after the concrete has been cast (or poured).
If a mix needs to be wet cured, it will typically be mentioned on the bag.
You can run into situations where a cement pot needs to be wet cured if you are working in dry and/or windy conditions, or hot conditions.
These climate conditions will speed up the curing time and may cause the concrete to crack during curing.
Other than obvious climate conditions, there’s not a way to know ahead of time if you will have this problem. Just be aware that the solution is wet curing.
I use Cement All for most of my projects and to date, haven’t run into the need to wet cure any of them.
Making Colored Concrete Planters
The easiest way to color a DIY concrete planter is simply by adding a pigment to the mix.
There are many types of pigments that can be mixed in with concrete.
You can use specially made concrete pigments which come in a powder form. You can also color concrete by adding either acrylic or latex paint to the mix.
Of course, you can always color cement and concrete by painting it after it’s cured.
Painting and staining concrete planters is done the same way you would paint anything. You can use a regular paint brush, a foam brush or a spray can.
Concrete takes well to any acrylic or latex paint. And if you do paint the concrete, I recommend sealing with either a concrete sealer or an acrylic paint sealer.
To get details about each concrete coloring method, take a look at my Concrete Crafts Pigment Tests.
This article has information on which colorants were best for retaining their color outside.
Sanding Concrete Planters
You smooth concrete planters by sanding them. There are many ways to sand a concrete planter.
Some concrete and cement mixes are more easily sanded than others.
For most mixes, you can usually get away with using a #100 grit sanding sponge. After sanding with the lower grit, switch to a #220 grit.
For mixes that are harder and not as easily sanded, I like to use diamond grit sanding sponges on planter edges.
Sealing Concrete Pots
Concrete planters do not need to be sealed unless you want to protect the finish.
A concrete finish is natural incredibly durable, but you may want to protect it from stains.
I only seal concrete planters that I have created a marbling effect. I also might seal when using a white cement and want it to stay bright.
Here’s where I mixed latex paint into the mix to make a Green Marbled Cement Planter.
Sealing a concrete planter will reduce its porosity which isn’t necessarily helpful.
The innate porousness of concrete helps keep plant soil from staying too wet and being over watered.
Another reason to seal cement and concrete is if you are potting a plant that requires acidic soil. More on this below.
To seal concrete planters, simply use a foam brush or rag and brush or rub on a concrete sealer after the concrete has completely dried.
Some concrete sealers also come as a spray.
After reading this, you may to check out my detailed tutorial on how to seal a concrete planter. It also has important information on why sometimes you shouldn’t seal your concrete pots.
Cleaning Concrete Planters
Concrete planters can easily be cleaned by either just using a dish detergent and warm water solution. Or for tougher stains, with bleach and water.
A typical ratio of bleach to water for cleaning purposes is one cap full of bleach to one gallon of water.
Concrete Planters And Plant Health
Concrete planters are great for many plants.
But one thing to know is that concrete and cement leach lime which is very alkaline and will cause the soil in the planter to be alkaline.
Plants like succulents thrive in this type of soil, but there are many types of plants that require acidic soil.
It will be important to know which pH condition your plant requires.
However, if your plant does require acidic soil, then there is a very easy workaround.
Simply immersing the concrete planter in water for three days will reduce most of the alkalinity, making it suitable for most plants.
I wrote an entire post discussing the cement and alkalinity issue and how to solve it. For more in depth information, please see Are Concrete Planters Safe For Plants?
Cracking Problems With Concrete Planters
If you find cracks in your concrete planter after you remove it from the mold, then you likely had too much water in the mix.
If you have obvious cracking while it’s curing then it is curing too quickly for conditions and needs to be wrapped in plastic and kept moist.
This in-depth article explains the reasons why your concrete pots keep cracking and how to prevent it.
- Please see the complete materials list near the top of the post.
First, you will choose a mold for your planter.
The easiest planter mold to work with is one that has smooth sides and is either straight up and down or tapers outward at the opening.
You will also need a smaller mold that you will insert inside of the outer mold. This will be the actual cavity of the concrete planter.
Make sure the molds allow for ¼” of space on each side and the bottom when placed inside each other.
To make the drainage hole for the concrete planter, take a piece of a drinking straw that's about ¼” high and use hot glue to glue to the bottom of the container.
Use hot glue to also fill in the top open end of the straw.
Mix the concrete to a thick milkshake consistency and then pour the concrete into the mold.
Fill this to about ⅔ full and insert the inner mold until you feel it hit the drinking straw.
Vibrate the outer mold by tapping the sides of the mold and carefully tapping it on your work surface.
- Let the concrete cure for the length listed on the bag of mix.
If you are using Cement All, then let this cure for one hour.
- Demold the planter by turning it upside down and gently tapping it on the table.
I recommend using a towel underneath to cushion the planter so it doesn’t fall out and chip.
- Pull out the drinking straw to reveal the drainage hole. Use needle-nose pliers if it sticks.
Sand any rough edges with #100 grit or #220 grit sandpaper.
For some great beginner concrete planter ideas, check out:
And for other concrete crafts tips, you can go here.
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