It sounds like your preserves are holding up well flavor-wise, even though they're changing color a bit. It's fascinating to hear about your experiments with peach pits! Your method for stratifying the seeds sounds well thought out. I'd love to hear how the grafting process goes and how many of the peach pits germinate. Keep me posted! Here are some cool tips for how to grow peach from seed:
https://gardenupcycle.com/how-to-grow-a-peach-seed/
