New growth is usually a brighter green. Lower, older leaves will be darker unless they're not getting light in which case they'll wilt and die. Best to snip those off at the base of the fan leaf and let the remaining stem fall off on it's own. I get discoloration on the tips when feeding too many nutrients. Not sure why she isn't flowering yet. Might want to change the light schedule in case it isn't an autoflower.
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