Reader Mail on Cleaning Mushrooms, Whiteboards, and Pfaltzgraff Dishes

Mary Hunt clears up a misconception of how mushrooms are grown.

The compost used in mushroom farming is scientifically formulated and contains various materials such as straw, corn cobs, cottonseed and cocoa seed hulls. Dmytro Ostapenko/Shutterstock

Dear Mary: In a recent column, you suggested to not wash mushrooms but to simply brush them well with a vegetable brush or clean towel. While I agree with you 99 percent of the time, on this one I had to write. Did you know that mushrooms are usually grown in manure? You must wash them. I use a commercial veggie wash and brush, too. —Patricia

Dear Patricia: Contrary to popular belief, mushrooms are not grown in manure. Mushrooms are, in fact, grown in a pasteurized substrate. Yes, this does contain manure, but once the whole process is finished, it is not even close.