I respectfully disagree completely. And you better be SURE when you say that I am wrong because you are actually giving misinformation about some guys plant and he doesnt know what to believe. Anyways.
Iron starts on the apical meristems, aka the center of the tops, and turns the foliage BRIGHT yellow/white.
also pay attention to the picture dude, the underside of the plant has bright yellow leaves from N def. it's spreading to the canopy.
Im well aware of how to diagnose nutrient problems. And the OP has nitrogen deficiency. You aren't looking at the pic close enough, and it being a top-down shot doesnt help. But it's working it's way up the plant.
THIS is iron deficiency. It yellows where the apical meristem is. Not all spread out like OPs.
http://www.growweedeasy.com/sites/growweedeasy.com/files/iron-deficiency-yellow-new-leaves-sm.jpg
He is using a really light soil and feeding really light nutrients. And he did confirm he's in veg still.
If your soil is correct your plant will take what it needs in nitrogen during flower. Other then that just don't. It's not that it cause extra growth or inhibits flower formation. I would love a source on that.
Sigh.... this is cannabis 101 dude. Less N in flower, more N in veg.
These are what excess nitrogen cause
" Adding too much nitrogen in the flowering stage can cause nitrogen toxicity even when you can see yellow lower leaves. Nitrogen toxicity in flowering results in smaller yields and airy cannabis buds, so make sure to watch out!"
The fact excess N makes the plant want to grow vegetation literally translates to the plant focusing it's energy away from bud growth in order to acomplish that. In flower the plant spends ALL its energy on buds. So if it wants to grow veg, that's going to be bad for flowers.
Source: Every grow guide on planet earth, every grower who has experienced it, and myself who has seen it first hand.
