Incorrect watering is one of the most common mistakes when growing cannabis. Watering too frequently leads to all sorts of problems, from mould and fungus to root rot and nutrient lockout. Underwatering dehydrates your plant and stunts healthy growth. Water less frequently so the soil can dry out between sessions. Underwatering cannabis is less of a problem. Should a plant temporarily droop from being thirsty, it will usually recover within hours once watered.