We have four blueberry bushes that we wanted to retain the moisture around. A business not far from us has cedar sawdust for free. We got some and spread it under our blueberries. Later, when discussing this with a blueberry farmer, he said that he wouldn't recommend cedar sawdust, but would prefer fir. Also, how often do you put new sawdust down? He said that they tried to do it every four years. Wanted to know what you thought.