After feeding your plants, discard all left over diluted Flourish Plant Food and clean the vessel with soap and warm water. It’s not safe to store leftover diluted Flourish to use at a later time (once diluted, pathogens are able to grow and contaminate the mix much more quickly!) . And the vessel should be cleaned well at each use to avoid any contamination. Always seal the Flourish Plant Food dropper tightly before storing.