growdiaries.com/diaries/244831-chocolate-kush-bruce-banner-sativa-hybrid-grow-journal-by-novc01 (Day 20 Last three photos)
I added 1/64th tsp water soluble P & K to my existing flower side mix last grow. Besides what I said below, it also hastened the grow
"PK Boosters are nutrient supplements that encourage plants to hit the flowering stage earlier by producing a chemical change within the plant. They contain both Phosphorus (P) and Potassium (K) which together will ensure increased flower size, potency and will speed up growth.
https://ghedirect.co.uk Let's Talk About PK Boosters)."
So adding these to your mix is dicey. A very small amount can push your plants towards toxicity. Stalks and stems start to turn red, some leaves yellow and brown spot. Toxicity, the stalks will redden and begin frothing.
Plants can still recover from this stress. From what I researched if your gonna do it, do it at the end of your third week. Don't wait until you're way into flower.