nutrients

my white widows are 2 weeks,just want to know when to start feeding them with proper plant food and what would be the best to use,i have been advised to use a+b is this correct?

anybody?
someone help me please lol

Not to sound like a complete asshole but in order for us to help you, you need to help yourself first. What type of nutrients? Lighting? This question has been asked a million different times in a million different ways on this forum a good place to start is searching on the forum, people that try to help themselves typically will get assistance, people that don't typically get ignored.