Does anyone know of a fireproofing spray that can be applied to mulch. I have a property whose mulch seems to catch on fire 2 or 3 times a year due to residents throwing cigarettes off their decks. If there is no spray can anyone think of an alternative to mulch. This is a college town so rocks won't work because along with the cigarettes getting thrown off the decks, so do beer bottles. Thanks for your help.