Problem: Overwatering your marijuana plants
Symptoms: Leaves curled down and yellowed; the top layer of soil is constantly wet, fungal growth, slow growth.
Solution: If the saucers under the pots still have water standing in them, the marijuana plants shouldn’t be watered. Water standing on the roots of marijuana prevents oxygen from reaching them, so the plants will suffocate. Let the plants dry out a bit between waterings and they’ll be fine. In my basement growing operation, I didn’t have saucers under the large tomato cans I was using as pots; rather, the water simply drained out of the cans’ holes and was collected in containers under the growing bench. Thus there was no way that the roots could be flooded. A final test is to poke your finger into the potting soil. If the soil is wet by the first joint down, don’t water. That’s a finger joint I’m referring to.