Too much light too soon. Clones cannot deal with intense light until they have roots. You can make them really happy by running a tube off a humidifier into the clone tent. Make the humidity 95-100% for the first 3-5 days. They love this and it will usually bring them back if you didn't...
Once a leaf is damaged it will not usually come back. Just make sure its not spreading to more leaves. I find that the height of the fan in relation the the plant is a major factor. If the wind is blowing directly on the plant its not as good as getting the wind to blow mostly just above the...
I have a strain that is supposed to be Jack Herer. I foolishly ran it in half of my room without testing it. At week 4 every single plant (about 30), simultaneously showed stamens, the beginnings of pollen sacks, in the flowers, mostly in the upper sections of the plants. I cut them all down...