Ashes go on the ground. Step on them and they vanish.

Buts usually go in the wood burner. I've also given them a proper burial by kicking a small divot in the ground with my heel, dropping one in and covering it with dirt. Usually it's pretty easy to find a small area devoid of grass for the purpose.

BTW, plural nouns don't use apostrophes -> How to Use Apostrophes | Scribendi.com