Horsetail Hair Rinse I know a few people have mentioned that horsetail strengthens hair and nails, but I didn't see any how-to's (apologies if I missed them!). Here are two simple methods worth trying: Break off a piece of fresh horsetail and rub on fingernails and cuticles. You will notice an immediate difference. This is a great one to use with friends who are still skeptical about the effectiveness of "herbs". Make a strong infusion of dried horsetail. After shampooing, work the infusion through your hair. Do not rinse out. The infusion will keep for almost a week in the refrigerator. Leda Meredith