Burmeseanswered grow question 4 years ago Hey friend, These yellowing leaves are suffered from Nitrogen deficiency.Eventhough plants don’t use much nitrogen in flowering stage compared to vegetative stage, they still need a bit touch of Nitrogen in early flowering days.Showing nitrogen deficiency at week-3 of flower is still early.So you need to add very small dosage of nitrogen to your plant.Don’t over use it, you will be catched by Nitrogen toxicity.Happy growing... ✌️