Q: Many large hickory trees drape over my concrete driveway. When the nuts fall, they leave a stain that can be best compared to an ink stain. Is there anything that will remove the discoloration?

A: Tannins, the broad class of chemicals that make up the staining juice of hickory and walnut nuts, have been used as colorfast dyes and inks for thousands of years. Once they stain cloth, fingers or concrete, little can be done to reverse the process. Applying bleach or hydrogen peroxide will lighten the stains but won’t completely eliminate them. Consider having your driveway professionally stained so the marks of the crushed hulls are less noticeable.