with any type of firewood green, seasoned or dry as the dogs last Christmas bone! it's just a good idea to sweep the flue whether it's needed or not. it's a good feeling to know it's not plugged. you will thank yourself as well as your insurance co for not having to deal with a bad judgment! fire happens when it's not expected!! for me it's like reading the electric meter..If I have anymore pine trees to come down I will let it age a bit before splitting to see if that helps. How often do you guys sweep the chimney? If I was to burn pine would I need to increase the cleanings (if it was properly seasoned for 2yrs)?