Depends on your grow. If you're in coco, you're feeding every time you water. If you're in soil, it'll be every other or every two. If you're working with autos cut their formulas by half or more depending. Feed and Water to runoff, and follow the newer charts on the website not what's on the bottles (they've changed over time). There's a PDF of Flora Trio that has 3 different versions, an aggressive, a medium and a light feed regimen. Each of the different schedules lists a total PPM/EC for the feedings...eyeball that and find the one that matches what you're looking to do or what your plants will tolerate.