PK Boost Timing

I would start right away, 500-1100ppm..

Dr. Bruce did a study on this and has concluded that this industry in general is giving way too much Phosphorus during the life of the plant. However, he did say that during the first weeks of flower to roughly the sixth week, extra phosphorous has helped increase yield. Just be careful as I have seen so many people ruin the plant using too much PK boost. Hope this helps.

Should be providing critical levels of p and k around roots the entire time. There is more than 1 study that shows amping these things up in flower or even the entire time is not actually causing any differences in yield or potency once over a certain threshold. Proof is in the pudding, or lack of proof in this case. P and K enter the plant through active transport more so than the other nutrients. This means when the plant needs it, it grabs it. this is why it's not so much about a high concentration but merely the "right" concentration so that it is easily availble and going above that provides zero benefit. it's one of the many things people have done and repeated without any proof of concept or any attempt to prove it helps, Like the obsessive need to flush before harvest even if the plant is perfectly healthy, that coco coir needs more Ca, 48hours of darkness, burning it, icing roots, etc etc... just a bunch of madness out there.

First 3 - 4 weeks of flowering is the best for P/K boosters.........waiting until the end is too late, as most of the growth has already finished. Start now, personally I would be using it already on these plants.

Hi growmie, for me I would wait at minimum one week before giving her some pk13/14 and have a eye on the leaves if the edges starting the getting light green then i would start with the min dosage .

Phosphorus is more so early seedling stage and early flower. and most potassium mid-end flower. add some silica too for trichome production and calcium and sulfur are going to be taken up more in flower as well.

I agree with asnoriu

Last 3 weeks of flower 8s best time for pk boosts.