Ashes to ashes

On an outing to drop off stuff at a local charity shop, I spotted a big plant in a pot standing outside, complete with label.
ash1

Then I realized it was not a label. Instead, it was an instruction or warning sign.

Dangerous plant? No.

Don’t water the plant? No.

This is not an ashtray? Yes!  Now look a little closer:

ash2

Well, it made me laugh.