Terracotta Flower Pots Mosaic Warning

Terracotta flower pots are highly susceptible to freeze damage because the material is extremely porous. Moisture seeps into the tiny pores, freezes and expands, and then the surface flakes off as shown below. However, it is possible to use terracotta as a mosaic base provided the mosaic is mounted correctly and the artist understands the limitations of the material.

Terracotta flower pots are highly vulnerable to freeze damage because they are soft and porous. The damage could have been minimized by sealing the pot inside and out with a tile and grout sealer.

Minimizing Damage To Terracotta Flower Pots

Freeze damage can be minimized by sealing the flower pot inside and out with a tile and grout sealer from a local building material store. Tile and grout sealers are silicone products that plug tiny pores and prevent moisture penetration. They can also interfere with bonding, so we recommend sealing the flower pot AFTER your mosaic is complete. Note that even if you do seal a terracotta pot very well with multiple applications of sealant, it still won’t last as long as a concrete pot would.

Concrete Pots Are Preferred

A terracotta pot might be an acceptable base for an abstract mosaic quickly made from random colorful tile, but detailed mosaic designs take more time and effort than that, and they deserve a more durable base. Concrete flower pots and planters are available at most lawn and garden centers, and whatever extra cost is well worth it. A single winter of hard freezes can totally destroy a terracotta flower pot left outdoors. Also terracotta is also easily broken and cracked during normal use.

Sure you might already have terracotta pots at home that you could use for free, but how much money are you saving if the mosaic doesn’t last six months? Once you take the time to mix up mortar and attach the tile, you’ll be glad you took the time to find a concrete base, even if your design is just random tile.

Use Mortar Not Glue

The tiles should be attached with thinset mortar instead of glue. White PVA adhesives such as the Weldbond we sell are water resistant when fully cured, but there is a difference between water resistant and water proof. Flower pots are containers full of damp soil, and that means the back of the mosaic will be continually subjected to moisture and acids from decaying organic matter. The acidity of the leach water means that flower pots may be a more extreme environment for mosaics than pools and fountains.

Thinset mortar can also be used to grout your mosaic. Both grout and thinset are powdered portland cement products, but the thinset is stronger and more adhesive. If you are going to have to purchase a powdered cement product to make the mosaic, get the better product (thinset), and use it for everything. You can even reinforce the inside of a terracotta flower pot by plastering it with thinset.


9 responses to “Terracotta Flower Pots Mosaic Warning”

  1. Molly Avatar

    Thanks– great info to spare us time on using terracotta. I’ll use a concrete base instead.

  2. Gabriella Smith Avatar
    Gabriella Smith

    Hello. Query from England.

    Does this hold true for indoor pots. I have a window sill full of them and would like to mosaic them. Can I use the tacky PVA I use on my indoor MDF bases if they are not going outside?

    Many thanks

    1. Joe Moorman Avatar
      Joe Moorman

      Hi Gabriella,

      There wouldn’t be an issue with freeze cracking, but moisture can migrate though the terracotta and weaken the glue. You can minimize if not prevent that by sealing the inside of the pot with a silicone-based tile and grout sealer. You can definitely use PVA and MDF for dry indoor mosaics.


      1. Gabriella Smith Avatar
        Gabriella Smith

        Brilliant! Thanks. I’ll have a go :0)

      2. Krista B Avatar
        Krista B

        What about using ge silicone II on a terracotta pot, grouting, & then sealing on the inside and out?

        1. N Moss Avatar
          N Moss

          Hi Krista, yes you could use GE Silicone II as the tile adhesive.

  3. Karen Smith Avatar
    Karen Smith

    Can I mosaic a flower pot that has already been glazed?

    1. Joe Moorman Avatar
      Joe Moorman

      As long as you test the glue or thinset to make sure it sticks, you can. We recommend thinset mortar instead of glue for outdoor projects.

  4. Susan Avatar

    so could one coat the entire pot with a modified thinset, would it grab on and stay put?
    I so appreciate you excellent articles and info.

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