[sling]

what type of miracle gro soil? Does it say "feeds plants for up to 9 months" on it? It could be lack of nutes if you're using the non-time-release soil (this is easier to fix than if you used the time-release).

That doesn't explain the turning up of the leaf, mine have curled under when that happens. What's the temp like at the top of the plant?

It's curious that the lower leaves are unaffected, that would be the typical nute burn I think, starting at the lower leaves and moving upward?

I'm no expert so please feel free to correct me.