This is my first ever grow and I have 2 bag seeds growing in potting mix. About 8 weeks old under fluorescent lights and I’ve just started hardening them off to be outside for the summer. I just started giving them fox farm big 3 nutrients after feeding them miracle grow plant food while waiting for the fox farm in the mail. They have both developed light brown/gray and brittle spots on lower sets of leaves. Although one plant is definitely worse than the other, the both have it. After reading some of Ed Rosenthals “marijuana garden saver” I suspect a possible potassium or calcium deficiency. Is my hunch accurate or could it be something else? Pictures are attached. Any/all advice is appreciated!! Thank you!
Welcome to Percys mate, I say it was caused by the Miracle gro, that stuff isnt good for cannabis plants, very strong. But you should stop using it now the fox farms is here though right? She should start picking up now, but only give her water for a few feeds, dont add any food to it at all. Let the plant eat whats in the medium first 
@macky Thank you!
yes, miracle grow is out. Should I defoliate the effected leaves or just leave it be? Hopefully she Bounces back, there’s definitely a learning curve at play 🧐
@goennersgreens I definitely would not defoliate anything at this point. If the leaf is damaged to a point of being useless the plant will drop that leaf by itself. The leaves still have usable surface to help capture energy. If you remove them the plant won’t get that energy plus it will need to replace them costing time and extra energy. Just change the feed like macky recommended, the plants will handle the rest right now.
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