Ratch33answered grow question 3 years ago If the problem starts at the top of the plant it’s an immobile nutrient deficiency. If the problem starts at the bottom it’s a mobile nutrient deficiency. Immobile nutrients are often referred to as micro nutrients and mobile nutrients are sometimes referred to as macro nutrients.
Light and heat over saturation can often be mistaken for deficiencies so be sure to check that off the list before making any drastic changes.
Once you figure out where the issue is coming from you can address it. Many times immobile nutrient deficiency is due to improper VPD and not a lack of nutrient in the growing medium.
Foliar feeding can be a great way of administering micro (immobile nutrients).
Mobile / macro nutrients = Nitrogen, Phosphorus, Potassium (NPK)
Immobile / micro nutrients = Calcium, Magnesium, Iron, Sulphur, Manganese, etc.