I think the switching to bloom nutrients is a money grab. The main thing is to use a good base of nutrients, and if growing with chemicals, slowly increase the PPM each week. If growing an 8 week flowering strain, increase base nutrients from seedling stage, up until week 6 of flowering, and then start cutting back in weeks 7-8.
Cutting back on Nitrogen in flowering is also a myth. All Nitrogen is to a plant if Protein. When a plant is flipped to 12/12, it will grow more than it ever has, and will also produce more hormones, and other chemicals. It makes no logical sense to cut off Nitrogen/ Protein when you are going to grow the most, and produce the most chemicals in your life. The important thing is the NPK ratio.
In an 8 weeks strain they may benefit from a 0-52-36 MPK boost in weeks 3-4, and in weeks 5-6 may benefit from an Epsom salts boost.
Hyrdo Gardens who makes plant specific fertilizers, and have since the 80s, and fertilizers in general sine the 70s, says going by tissue analysis, they came to the conclusion to use a base formula of
4-20-39
15.5-0-0 Calcium Nitrate
Epsom salts, is the most correct ratio throughout the plants life cycle.
Just increase the PPM as the plants get bigger, usually a small amount each week from seedling- week 6 of bloom, with a boost in MPK at weeks 3-4, and Epsom salts boost in weeks 5-6. They do not change the basic formulation, only the PPM, and a boost of MPK, and Epsom salts in specific weeks.
If the plants are shorter, or longer flowering, adjust accordingly. And some strains may need more Iron, but this is not for the majority of strains.
They say that basically the best ratio of NPK is a 1-1-2 all through the grow. 19.5-20-39.
