Would you like to know what the number one cause of failure in the marijuana grow room is? You guessed it, its overwatering. An overwatered plant as a seedling will die more quickly than one can believe they also suffer from something called damp-off due to overwatering. Damp-off is when you walk into your grow room early one morning and see that 6 of your twenty seedlings are dead, apparently having died overnight. The adult overwatered plant, although it may not die, will never achieve optimum growth in either the vegetative or flowering stage, it will always seem anemic and slightly droopy. They will often accrue a yellowish tinge, which could mean they are getting chlorotic, due to the overwatering.
Some dangers of overwatering your marijuana plants
One of the main problems with overwatering a marijuana plant is that you are going against its entire approach to growth. Marijuana likes to be watered well and hard, and then not watered for several days in order to process all the nutrients it possibly can from the soil. Allow things to dry out completely before you water again.
Depending on your environmental factors, that can take anywhere from 2 to 4 days. A good rule of thumb is to push your finger into the soil at the top of the pot if you get at least an inch down, and the soil is nice and moist, wait at least one day before you water again. When you overwater a marijuana plant, you flush out all of the nutrients before the pot plant can uptake them.
You never allow the roots to completely dry out. It is essential for the growth and development of both the roots and the rest of the plant structure. Doing so will weaken the plant systemically. Marijuana plants need to have their roots drained fully before you re-water, so ease up on the watering. If your plants are drooping and yellowing, and you keep watering them in response to that drooping and yellowing than you are killing them slowly.
Seedling damp-off occurs when too much water is incorporated into the marijuana plant.
The number one cause of seedling damp-off is overwatering. There is no reviving a damped off seedling, they are done. Overwatering the seedling results in a pathogen forming within your soil. This can kill the seedling in less than 8 hours. Yet one more reason not to overwater.