Nitorgen deficiency - recovery time, amount?

I've had what was diagnosed as a nitrogen deficiency in about half of my crop.(4 weeks into flower)
I'm 5 days into treating them with a nitrogen based fertilizer as advised and was just wondering what sort of recovery i should be seeing if the diagnosis was correct? and how long i should treat for?
The plant that was effected the most seems to be showing no color change in the affected leaves, however new growth seems to be a healthy green.
Will the old leaves recover their color or is it just new growth as i'm seeing that will be ok? How much will this affect the plant/yield for the rest of the cycle?
thanks

 

you are correct that the old effected leaves will not recover much, seeing that your probably about half way though flowering its a common time for N deficiency to happen. you may want to add a small amount of the high N fertilizer in with your regular flowering schedual. it shouldnt be a huge problem for your end yeild but then nothing grows like a perfectly healthy plant.

 

To much N in bloom is counter productive as N can block out the up take of PK and bud will tend to grow thin and stretched not tight and compact. There are two schools of thought on N def in bloom some would say a healthy looking green plant is a happy plant and others would say theres energy in there them leafs and by letting them slowly yellow over the bloom your releasing whats been stored.