There are lots of choices for non-toxic sealants and non-toxic paints for terra-cotta planters and pots in this article that are not widely known.
Almost all of the conventional recommendations out there are for products I would definitely not use. I wouldn’t want that exposure to VOCs and I want my plants to be happy and healthy too.
This article goes over all-natural and non-toxic synthetic sealers for inside and outside the terra-cotta clay pot.
I also take a look at natural and synthetic paints for the exterior of the pot, and sealants for over those paints to prevent the paint from peeling off.
We want to make sure we are providing the environment that the plant needs to thrive in, so some of these sealants will be close to water-proof and others will be breathable.
We don’t need to use toxic sealants to provide any of our sealing needs.
This post contains affiliate links. Upon purchase, I earn a small commission at no extra cost to you.
First, When do you Seal?
Protect Acrylic Paint
If you are using acrylic paint on your terra-cotta pots then you will want to seal the inside before painting the outside to prevent water from migrating through and damaging the paint with time.
Another reason some people seal their painted pots (over the paint) is to protect painted work.
Water-Proof the Saucer
It’s also a good idea to seal the saucer so that the water doesn’t soak through and damage the surface that it is on. Especially if the plant is indoors.
Reduce Permeability of the Pot
By sealing the pot on the inside, the outside, or both, you are reducing the natural breathability of the clay so you will have to find out if that affects the kind of plant you have. Some plants do better with the terra-cotta sealed on the inside or on both sides.
Not all sealants are equal, some make the pots almost waterproof and others leave the pots very breathable.
Plants that do Better with More Permeability
One vendor of ceramic pots recommends leaving the ceramic breathable and replanting the plant into soil for Monstera, Philodendron, Dieffenbachia, Cactus, Ficus, Pachira Aquatica, Hoya, etc.
Plants that do Better with Less Permeability
Terracotta pots, especially smaller ones, can lose quite a bit of water through the terra-cotta walls. If the plants have high water requirements, or don’t do well with the wetting and drying cycle, sealing your terra-cotta pots (inside or out) will be helpful to the plants.
For plants that need a lot of water, they recommend keeping your plant in a plastic pot and then placing it in the terra-cotta pot, or sealing the pot well, for example for Calathea, Maranta, Fittonia, Begonia, etc.
Note: Make sure the terra-cotta doesn’t already have a glaze or sealant on it before you seal it.
Non-Toxic Sealants for Inside of Terra-Cotta Pots
1. An All-Natural Drying Oil
This is the sealer to use if you want to go all-natural and pure + you want a durable but breathable sealant.
Tung Oil is the most durable of the drying oils and will give you the most protection on terra-cotta, it’s definitely the best drying oil for the inside of terra-cotta. You can use other drying oils like Hemp Oil but that one is not as tough. Hemp oil is better suited for the outside of the pot.
It is still somewhat breathable, unlike many synthetic coatings, but this is a tough natural coating.
You don’t need to thin the Tung Oil with solvent for the terra-cotta since it is so porous. Let it absorb and reapply as many coats as it will absorb, typically that will be 2-3 coats. Wait 15 days before potting the plant.
It’s important to note that the terra-cotta has to be unglazed and not already sealed for this to work. The best way to test if this is the case is just with a little bit of water. If it absorbs then it’s unsealed. If it runs off, then it probably has some kind of sealant on it that would prevent the Tung Oil from absorbing.
Any time an oil is applied to the terra-cotta it will darken the color of the terra-cotta, just like when the pots get wet. With oil though, that change will be permanent.
The downside to using Tung Oil for this application is that the oil might seep through, giving you dark spots on the outside. I used Tung Oil to seal small terra-cotta pots and it did not seep through.
I was really happy with Tung Oil as a sealer on the inside of the pots (and on the outside too for another project). More photos throughout the article.
If you want to see my step-by-step on how to seal with Tung Oil and then paint with natural paints see this visual post.
2. A Waterproofing Sealant
This option is the absolute best water-proofer for inside the pots if you need to stop water and don’t need it to be breathable.
AFM DynoSeal is a non-toxic waterproof sealant used on the inside of planters and pots.
If you need a really tough thick coating inside the pot, this is the way to go to prevent water and moisture from seeping through. Once it is cured it is considered safe for the plants even if they are edible plants.
It will provide the best protection against water seeping through to your paint on the outside.
Buy DynoSeal from the Green Design Center.
What not to use inside the terra-cotta pots/planters:
- I like to avoid the higher VOC options like 511 sealer.
- Avoid masonry sealants with toxic PFAS.
- Almost all water-based sealants like acrylic sealants or acrylic paints cannot hold up inside the pot with the moisture content there.
- Shellac cannot hold up to water immersion or being under the soil. It will lose its bond to the surface with time.
Non-Toxic Sealants for the Exterior of the Terra-Cotta
There are a number of options to seal the exterior of the pot. We don’t need to worry about constant wetting from the soil which breaks down many water-based sealants and we don’t usually need the exterior to be as waterproof or durable.
We can use natural oil-based sealant here, non-toxic penetrating sealers for an invisible look, or acrylic sealants and paints.
1. Invisible Look, 0-VOC Sealant
This is the best sealant if you want an invisible look penetrating sealer that is totally non-toxic.
AFM Penetrating Waterstop is an invisible look sealant that is zero-VOC and close to odorless. It’s water-based and the ingredients are listed as water, silicone solution, and potassium hydroxide.
If you want the outside of the pot to still look like the original terra-cotta then this is the sealant to go with.
It also leaves it somewhat breathable which is good for some plants. It’s a great replacement for toxic penetrating sealants.
ECOS Stone and Tile Sealer is a similar sealant. The ingredients are water, silicone, and a sodium salt.
Buy Penetrating WaterStop from the Green Design Center.
2. All-Natural Penetrating Oils
Tung Oil is my top pick for an all-natural option that is still durable, and if you don’t mind the darkening effect.
If you like the darkened look of the oils, Tung Oil is an all-natural, totally healthy option to seal the outside of the terra-cotta pots.
But if you want the toughest possible natural sealant, stick with Tung Oil!
I used Tung Oil on the outside of some of my terra-cotta pots (pictured above) and was very happy with it. I painted over the Tung Oil sealant (on half of the pot) with natural Linseed Oil paint. The step-by-step process is documented here.
Buy tung, hemp, and walnut oils from The Real Milk Paint Company.
3. Shellac, A Natural Wax
This is the best all-natural option if you want it to be shiny, you want a lot of water-proofing, and the pot will be used indoors.
For an all-natural shiny look on the outside of your terra-cotta pots, shellac is definitely the best option. It’s usually not used outdoors so it would be best suited to indoor potted gardens.
Shellac is a natural wax that comes from a beetle mixed with alcohol. If you want to go for the purist option, you can buy real shellac flakes and mix them with a high alcohol percent ethanol.
I also use Zinsser shellac which comes premixed.
Buy both types of shellac via Amazon.
4. A Clear Sealant
This is the top clear sealant to provide a lot of protection on your bare or painted exterior pots.
If you want a clear synthetic coating that is tough and can be used on outdoor pots, use Safecoat Poly EXT for a clear coat look. It’s not an invisible look – you will see it as clear-coated.
You can also use this non-toxic sealant over your water-based paint, to protect your paint job on the terra-cotta.
Buy Poly EXT from the Green Design Center.
Non-Toxic Sealant for the Saucer
You can use one of the following to seal the saucer: Tung Oil inside and on the outside of the saucer to limit water migration; AFM Poly EXT clear synthetic coating (but if you often have water sitting in the saucer that will break down this coating with time); or use the super hardy AFM DynoSeal on the underside of the saucer (because it’s a weird dark color that you probably don’t want to see on the top).
One additional solution to the water soaking through and damaging surfaces below is to add felt or cork pads as coasters under the saucers. (I find cork to be a little smelly due to the glues, just a warning for anyone super sensitive).
Non-Toxic Paint for Terra-Cotta Pots
Most people find you do need to seal clay pots on the inside and outside before painting them due to the water pressure that comes through the pots. If you don’t use a proper sealant on the inside (and sometimes on the outside under the paint as well), synthetic paints will bubble, crack, and peel.
However, when we are using natural products, there are some exceptions to this.
1. Milk Paint (All Natural)
This is the most natural option with the least odor (no odor in this case). It will give you a beautiful matte look.
Milk Paint is made of 100% natural ingredients with no additives or preservatives. It leaves a beautiful natural matte painted look on terra-cotta. This is the purist option.
I love the milk paint colors myself and how the finish looks. I used it on my terra-cotta pots.
It comes in a powder form that you mix yourself – that is how you know it is free of preservatives and biocides.
If water does soak through to the outside, the milk paint will not be damaged by this. It will temporarily change the color of the paint, and you could damage the paint job if you touch it while it’s wet, but if you don’t touch it it will go back to normal after it dries.
To paint your pot with milk paint, you can do a solid color or a design on the outside. Use 2 coats of The Real Milk Paint brand paint for best coverage. Optionally you can buff it with a soft cloth or scrubby pad if you wanted to make the paint velvety smooth.
(Many colors of milk paint are not food grade, so don’t use it on the inside. You can check which colors are food grade here).
For the most protection, you would protect the paint by applying Tung Oil to the entire pot, sealing it inside and outside over the milk paint. If you are painting with a lighter color of milk paint, you can use Hemp Oil over the milk paint because it doesn’t change the color of the paint as much.
You can also leave it without a sealant on the outside (which is what I did above). You don’t have to have a sealant on the inside to use milk paint on the outside of the pot.
You could use AFM DynoSeal on the inside of the pot to completely protect the paint from water migration.
You can also use a clear coat over it.
Buy milk paint in 56 different colors from The Real Milk Paint Company.
2. Acrylic Paint (0-VOC)
These two brands below are the top picks for zero-VOC acrylic paints. These could be used on indoor and outdoor pots.
Acrylic paint works perfectly well on clay pots like terra-cotta and it is what most DIYers use. Make sure you have a sealant on the inside to prevent water from soaking through and damaging the paint on the outside. That is a must in this case.
ECOS paints is also a great zero-VOC paint for terra-cotta. It’s the favorite paint brand for the chemically sensitive.
You can also use AFM paints. They recommend DynoSeal on the inside of the pot for a super durable coating to stop water migration there, then you can go use their Transitional Primer as your sealant and primer on the outside (super hardy), followed by their Exterior Satin paint. This is the best combo if you want to go with acrylic paint.
3. Linseed Paint (All Natural)
This is a good choice if you want something natural but with more durability than milk paint and you don’t mind Linseed Oil odor.
A totally natural paint like Allback’s Linseed Oil paint works well on porous materials like terra-cotta.
If you do well with the natural odors of Linseed Oil, this is a unique all-natural paint.
I used this on the outside of some of my terra-cotta pots (pictured left, documented here). The best part of this paint is that it can go over an oil finish (like Tung Oil). I had finished the inside and outside of the pot with Tung Oil before painting it, to reduce porosity of the terra-cotta.
Linseed oil paint is not totally food safe (because of the Manganese driers and some of the pigments like Chromium), so don’t use that on the inside of the pot.
Buy Allback linseed oil paint via their website Sage Restoration.
4. Spray Paint (Low Odor Options)
If you need an aerosol spray paint for your terra-cotta projects, water-based spray paint is the way to go to get the least toxic option.
A lot of people use spray paint on their terra-cotta pots.
Most spray paint is solvent-based and is not non-toxic. Though I do review some solvent-based spray paints here, pointing out when they come to a complete cure.
There are also a lot of water-based spray paints that will work well on terra-cotta and these are far lower in odor and cure faster as well. I mention those brands in the post on non-toxic spray paint.
Buy Montana Water-Based Spray paint and many other brands via Amazon.
Corinne Segura is a Building Biologist Practitioner with 8 years of experience helping others create healthy homes.