Hi David, A Southern German folk herbalist, as well an US herbalist (I sadly don't remember who it was or I would have asked them), stated that nettle leaves shouldn't be picked/used anymore after the summer solstice. Since I could nowhere else find any supporting information for that, and my grandma whom I learned my share of folk herbalism with used nettle leaves as spinach-like food all year round, I didn't give it much thought anymore and wrote it off as an old folk tale. Now I was revising the nettle's MM sheet and found your note "Avoid gathering older Nettles leaves as they contain crystoliths (calcium carbonate) which can irritate the kidneys and GI tract.". From your experience, would you say that this could be the reason for the advice to not gather nettles after the summer solstice, because those are then the "old leaves"? Does this apply only for medicine making and would cooking the leaves as a food render the crystoliths innocuous? If you would cut the nettles around June and then pick only the upper four to six leaves of the new growth, could this be used to make medicine with like from the spring growth? Thank you.

From your experience, would you say that this could be the reason for the advice to not gather nettles after the summer solstice, because those are then the “old leaves”? yes, I believe that is the case Does this apply only for medicine making and would cooking the leaves as a food render the crystoliths innocuous? NO If you would cut the nettles around June and then pick only the upper four to six leaves of the new growth, could this be used to make medicine with like from the spring growth? yes, we discussed this in class, if you cut the plant back, new growth can be used