Dave's got you covered. You "use" whatever will maintain the leaves in a healthy condition until harvest, and most "bloom" foods won't guarantee that. In fact, the use of bloom foods during flowering usually works against you.
There was a time when I would have disagreed with Uncle Ben on the bloom foods, and I guess to a slight degree I still do. I used to believe in them wholeheartedly. Then I started having a problem here and something odd happen there and I started backing off on them a fair it. I will still use them but sparingly.
After wondering why that was happening I thought about the strains it was happening with and came up with a very rudimentary purely assumptive theory. The strains were basically mutts, Heinz 57 Variety strains, ones that were made up starting with pure landrace strains used to make crosses that then were used to make crosses and triple crosses that then went into other crosses and sometimes more triple crosses until finally they were released as being the latest and the greatest. The landrace strains were from differing parts of the world where they would have evolved under very different conditions to exist in soil that had very different nutritional elements, mainly as in differing amounts but in some cases just different.
It made me wonder if in strains that have such amazingly varied genetics in them, that would bring with them differing needs for optimal health and growth and production, that possibly we are reaching a point where a one size fits all fertilizer for vegetative growth and another for flowering just won't or don't adequately meet the plants needs and that might, at least in part, explain some of the oddities and problems people see now and then and cannot explain because going my what people have been taught and going by instructions everything should be cool and the gang.
Some people have been going all Lady Gaga over Super Lemon Haze. Take a look at it's lineage and think a minute about how with all that variety of genetics in it, or something along those lines, might it not have nutritional needs that will differ from what we can pick from column A or column B?
Maybe I am just high but at times I wonder if some breeders are not getting to the point where they are creating Frankenstein s monsters that could turn out to be real pains in the pains in the butt given what we have to chose from for ferts.
With experience, you're gonna find that if you've doing fine during veg, your troubles begin about the 3rd week into the flowering response. Remember, I told you so.
I have another theory about that one Uncle Ben, one that if correct I used to be guilty of. Sometimes people really pour on the ferts in veg trying to get all the growth they can. I used to use them heavily enough that I would look for the very slightest bit of tip burn and then back off just slightly and figured that I was then giving my plants the maximum they could use.
Like you said three weeks into flower, even though I switched to flowering nutes, I would at times see problems. I think a buildup of vegging nutes occurs and even though someone switches to flowering nutes there is still a fair bit of vegging nutes left to be used up and the combination results in various different problems. I am fairly sure that is why people will see 'the claw' in flower. That's from excess nitrogen and even with lower nitrogen flowering nutes if there is a buildup of vegging nutes left behind the person is unintentionally giving their plants excessive amounts of nitrogen. With the leftover ferts it throws the entire balance off of what plants need while flowering, at least until they are used up or unless someone waters enough to in essence have performed at least a partial flush.
It is just a theory of mine but it seems to fit with problems I have seen in the past and has been enough for me to alter some things I used to do and since then things flow a lot smoother for me.
Doing well brickman...... Hope it's going good for you too. Happy Turkey Day!
I'm glad to hear you are doing well, and I hope the same goes for Auntie.
With Christmas not all that far away I hope the two of you are planning on spoiling yourselves a bit more than normal now that you have a couple more quarters in your pocket and a few more green pieces of paper with pictures of presidents on them lying around than in the past.
Life is short Unc, so live it up a bit! You can't take it with you and you don't win a prize for leaving the most most behind .. so enjoy!