Investigators say a cigarette that someone put out in a container of potting soil sparked a fire that left a Kansas City home in ruins.

The cigarette and the potting soil smoldered for at least four days before igniting last week and setting the house on fire. No one was injured, but the flames quickly spread through the house and the roof.

Investigators reported their findings this week. Authorities say it’s a good reminder that potting soil is flammable.

An education specialist with the fire department in nearby Overland Park, Kan. says potting soil looks like dirt. But Tricia Roberts says it contains a large proportion of organic matter, such as peat moss, that easily catches fire when it dries out.