I bought 2 ferts from my local flower store, one with NPK: 5-6-8 and another with:8-8-6. Or I can mix both (1/2 part of each) to get a NPK of: 6,5 - 7 - 7 Which one should I use for flowering?
I would tend to think the latter of the two, but the nitrogen amount is the same as the phosphorous. You usually want a higher phosphorous percentage, but you really don't need as much nitrogen when flowering. It's kind of a toss up between the two. I'm sure they'll both work fine. Maybe mixing them is your best bet.