Permanent plant labels

Thank you all. I posted because permanent markers have invariably let me down of late, so will definitely look into your suggestions.

That’s a coincidence, I bought some posh large black birch ones yesterday which came with a white oil pencil. It says that the marking is permanent until removed with white spirit. They were £8 for 10 labels, but the pencil will last ages so I will use it on other labels too. Mine were from the National Trust shop in Corfe Castle, but they must be more widely available, the manufacturer is Sting in the Tail England.

I use black plastic ones and use a fine silver permanent marker (IIRC from Amazon) to write on them. They last for years

Use a permanent marker pen on plastic or wood. Alternatively buy some copper labels which are expensive and etch or scratch on.