Stonerdanswered grow question 4 years ago You are indeed correct!! this is a Phosphorous (P) deficiency which is normal during the flowering stage *This doesn't mean you can ignore it*. Try increasing the flowering fertilizer (usually contains PK) by around 20-30% and see if it makes any difference, if it does help but not completely then increase it a bit more. If nothing changes then check the pH levels of your irrigation solution if its acidic (low), ideally you'd want 6.0-6.5 when growing in soil.
Other than the deficiency grow looks amazing! keep it up!
Happy growing :)