Howdy RFheavy, I keep track of germination date, weeks in vegetation or bloom, daily records of times and actions (feeds, drain, changing ice bottles, etc.), water and air temperature, relative humidity, and pH measurements of drainage and feedings. I also keep track of nutrient and supplement usage as well as the amount of water consumed by the plants during the feeding cycle. I also note down any anomalies, bugs, leaf spots, or any other notable occurrences. I'm not as organized as others, I keep notes in a small (3"x5") note pad for the daily stuff and a calendar for the long term planning and record keeping.