Cigar Ashtrays

[DeeDubya]

I've always wondered, how long does it take a cigar butt to break down in soil or compost?

They fall apart as soon as they get wet. Breaking down into basic organic (usable) compounds will take between 47 and 116 days if kept moist. About the same as other large stemmed plant leaves.

Try this. Pitch about 10 butts in a can of water. Let them soak overnight. Then drain and chop into fine pieces. Spread them on your lawn in about a 20" circle, work them down into the grass and water them in. You won't have to mark the spot, because in about a month you can easily see the dark green and extra growth.

Edit to add: I omitted composting for the lawn application because, your lawn has it's own built-in compost layer called "thatch", a thin layer of clippings and other organic material that builds up over time beneath the turf. You should never let the thatch layer get too thick. But, under normal conditions it will decompose mulched clippings and introduced lawn mulch.