Nitrogen and phosphorus
Nitrogen early signs
lower leaves lighten and tips begin yellowing
Nitrogen mid stage
yellowing spreads upward and leaves turn pale green
Nitrogen late stage
severe yellowing and browning, leaf drop and clear stunting
Phosphorus early signs
darker green leaves with a purplish tint on stems
Phosphorus mid stage
purple deepens and leaves darken with purple tones
Phosphorus late stage
necrotic dead spots, poor flowering and leaves that can die off
Potassium and magnesium
Potassium early signs
yellowing or burn on tips with slight marginal yellowing
Potassium mid stage
yellow or brown edge damage spreads and leaves start curling
Potassium late stage
crispy brown margins, severe edge curl and weak stems
Magnesium early signs
light green between veins on lower leaves
Magnesium mid stage
interveinal yellowing increases and leaves curl
Magnesium late stage
brown crispy spots, severe chlorosis and leaf drop
Calcium
Calcium early signs
twisted or curled new growth with small rust spots
Calcium mid stage
more rust spots appear and new leaves deform further
Calcium late stage
severe deformation of new growth, tip dieback and weak overall structure
Common causes listed
pH imbalance or lockout.
Overwatering or underwatering.
Root damage.
Incorrect EC or nutrient strength.
General nutrient imbalance.