Question
Hi Charlotte,
My question is can old sign posts be used to create raised beds? A county employee gives us old sign posts that are damaged to burn in our wood furnace but I'm not sure if they might have been treated with something to make them rot resistant that would get into my vegetables if I used them to make raised beds?  

Answer
Ho Jo;
Treated wood is dangerous to burn too.
You don't want to use treated wood, whether it has been treated with something to resist rots or insecticides, inside for heat, in a smoker or BBq for cooking food, and you don't want to use it to build raised beds for flowers or food planys.
Most treatments will poison the plants and kill them, and of course, burning the wood brings the toxics from the treatments or insecticides into the air you breathe if you are using them for heat.
Touch thing to decide.
Treating for termites is not necessary, just mix cedar bark mulch in with your soi you fill the beds with, and termites will stay out of it.
I made raised beds from landscape tembers ( untreated ) and they have just started to decay. I made them bout 15 years ago.
I am having to change them this year.
Charlotte