Problem Solver

Calcium deficiency

Rusty brown spots and twisted, crinkled new growth. Common in coco and with soft or RO water, and often an uptake problem caused by pH or humidity swings.

Iron deficiency

The newest leaves go pale yellow with green veins. It's almost always pH too high, not a lack of iron.

Magnesium deficiency

Yellowing between the veins of older leaves while the veins stay green. Very common in coco and with soft or RO water.

Nitrogen deficiency

Lower leaves fade evenly pale, then yellow and drop, while new growth stays green. A little lower-leaf fade late in flower is normal.

Nutrient burn (overfeeding)

Yellow, then brown, crispy leaf tips that spread inwards. The feed is too strong or salts are building up. Cut back; don't add more.

Nutrient lockout and salt build-up

Several 'deficiencies' at once that don't improve when you feed more. Usually pH out of range or salts building up in the medium.

pH drift

Feed or run-off pH creeping outside 5.5–6.5. Slight drift inside the window is fine; outside it, uptake suffers and lockout follows.

Phosphorus deficiency

Dark, dull or bluish leaves, purple-red stems and slow flower development, often worse when roots are cold or pH is high.

Potassium deficiency

Edges and tips of older leaves go yellow, then brown and crispy, with weak stems. Check pH and EC before reaching for more feed.