An organized Witch...

... is a happy Witch! Keep track of your herb shelf in a small notebook. If your cupboard is anything like mine, boxes and bottles are stacked to the rafters and you can only see the "front layer" of your current inventory - and, of course, the rue jar is in the back. If you are keeping a notebook with your "stock" listed, you will know if you need to visit the store, or if you just need to dig.