Nineteenth-century German farmers practiced a trick if they had a rather sad looking horse they wanted to sell. They collected nettle seeds and fed a handful a day to the horse for two weeks. The horse’s coat would brighten up, and the horse would shimmer with new energy and life. After a couple of weeks with the new owner, the horse was back to its sorry self.
To collect nettle seeds, cut off whole nettles around now, when they are loaded with seeds still green. Hang them up upside down, two at a batch, so they will dry out and the many insects, spiders and who-all-else on them will find new places to hang out. When they are dry enough that the stalks break rather than bend when folded, put on a pair of gloves and scoot the seeds off the rest of the plant. Now, still wearing gloves, press the seeds through a sieve. This removes the stinging hairs.
Your nettle seeds are now ready to eat. Raw. For example on a salad. Or in some soy yoghurt. Or out of the palm of your hand.
A tablespoon or two a day for a human corresponds to a handful for a horse.