TheXriddler
Member
Storing humidity box on top of T5 lights, forgetting it's there when raising the light and spreading seedlings across the room... Thankfully all have come back to growing, but they were pretty shocked by it, as was I 

Big mistake is trying to half ass it. dont waste your time and money on things that wont yield much in the end (aero garden). if your going to take the risk in the first place do it right the first time.
My biggest mistake was showing my girlfriend my grow.
I know more people have mistakes, don't be afraid to share. It's so other people can learn.
I've made a bunch...Used MG nutes (really harsh on the plants), used really hard water to the point of nute lockout, stopped using Nitrogen alltogether in flower (those two together killed all of my fan leaves, man were those buds small), overwatered, underwatered, let a caterpillar eat two young seedlings, harvested early... I'm sure I've done more stupid shit, that's off the top of my head.
I was wondering if everyone could share their biggest mistake they made when they began growing, just so others won't do the same.
I'll Start
One of my biggest mistakes was buying soil from wall-mart.