I have a four plants growing under a 600 watt MH lamp. Each plant is in a 5 gallon bucket filled with store bought potting soil. Everything was going great until a couple weeks ago when the leaves started to turn yellow and brown and then completely die. Eventually all the leaves came off and the plants withered and dried up. They crumbled to dust even though I watered the hell out of them. What did I do wrong?
I’m gonna go out on a limb and guess that you fertilized your plants to death. It’s a common mistake because lots of people think that more fertilizer equals more buds. So they throw an extra scoop or two in the mix. If you gave them a full dose or more of fertilizer with every watering then the nutrient levels would have quickly built up in your soil until they reached toxic levels. In the end it sounds like the high nutrient salt levels caused a condition called reverse osmosis that actually sucked the water out of the plants. This is why the plants crumbled to dust even though the soil was wet. Next time try fertilizing with a half strength dose every second or third time you water. You should also check for heat stress place your hand over the tops of the plants for thirty seconds if the heat from your lamp gets uncomfortably hot then you will need to raise it a bit.
Don’t beat yourself up too much all growers make mistakes and lose a few plants along the way. All we can do is learn from the experience and try again till we get things right.
Better Luck Next Time.