Here's the engineering bit witches have known for centuries: Phytochemistry peaks with the photoperiod. St. John's Wort. Lavender. Mugwort. Calendula. Chamomile. Their compounds are literally at their highest concentration when harvested at the solstice. In Wales they call Litha 'Gathering Day' for this exact reason. The folk knowledge was right. The labwork just took longer to catch up.