How do I fix plaster planters

If they are super heavy, they may be concrete. If plaster, they aren't outside pots and the weather is causing them to flake. Either way, you can buy plaster patch or concrete patch at a hardware store like Home Depot. After the patch, you'll have to paint them with an exterior paint.

Its sounds like your pottery needs to be sealed, that water and weather conditions are penetrating the surface pores and resulting in flaking and damage. Terra-cotta will do this.

I have a great fix for broken pottery repairs and plugging drainage holes, and it repaired my cement dog statue - this product might possibly be your answer. You would have to figure out where to apply this clay like putty as it cures quickly.

I keep it on hand for all sorts of home -craft -indoor -outdoor- wood rot -elliptical pedal -pottery repairs- candlestick- jewelry-concrete dog statue repairs. Too many to list. For me it’s a miracle producing product. Please have a look at it and see that something you would like to consider. Its about $6 a tube at Lowes in the plumbing department.

“Putty characteristics

Steel-filled material, mixes in your hand and hardens in minutes

Suitable for plastics, metals, fiberglass, concrete and ceramics

May be drilled, tapped, filed, sanded, sealed and painted when hardened

Non-toxic material contains no solvents

Will not shrink”

Consider the epoxy putty for your repair needs.

https://www.oatey.com/ASSETS/DOCUMENTS/ITEMS/EN/Epoxy_Putty.pdf>>