Its not true that you should change over to a Flowering formula when switching from Veg.
All they need is an ever increasing amount of fertilizer/PPM.
Hydro Gardens, who have been making Plant Specific Fertilizers since the 70s, says weed needs a ratio of 1-1-2 throughout the whole growth process. This was determined by Tissue Analysis.
They make a base formula of 4-20-39, and then add Calcium Nitrate-15.5-0-0, and then add Epsom Salts. They also state some strains can use a little bit of extra Iron, with the emphasis on some strains, and not alot of extra Iron. Most strains dont need it.
This basically equals out to a 19.5-20-39.. Almost the same as their Tomato formula. Except the Tomato formula uses a 4-18-38 ratio as the base. They also add Calcium Nitrate, and Epsom salts to the base formula.
Going by Tissue Analysis, weed likes 2x the amout of Potassium vs Phosphorus, and Nitrogen.
Its fake news to cut Nitrogen during flowering.
All Nitrogen is to a plant, is Protein. Humans eat Protein, and change it into Nitrogen. If either a plant, or a human doesnt get enough Protein/Nitrogen, we start cannabilizing ourselves. Humans consume their muscles, plants consume their leaves. Thus why athletes try and stay in Positive Nitrogen Balance, and is why athletes, and people in general should eat small, frequent meals, with an emphasis on Protein. Especially Diabetics.
A marijuana plant is going to do the most growing during its life, when its switched to flowering. It makes no logical sense to cut protein, when one is trying to grow, and put on mass. As is stated. All you need to do is keep a 1-1-2 ratio, supply Epsom Salts, and keep upping the PPM up until the last 2 weeks before harvest.
It may beneficial to boost the Phosphorus, and Potassium during weeks 2.5-6 ( Mono Potassium Phosphate ) on an 8 weeks flowering plant, while still giving ever increasing PPM of your basic 1-1-2 formula.
As of right now, Hydro Gardens isnt making fertilzers, because of a shortage of the chemicals they need to make their fertilizers. They make dozens of plant specific fertilizers.
But Id try and find a ratio of 1-1-2, or as close as possible.