Nutrient Burn in Hydroponics — Symptoms & Fix

Quick answer

Symmetrical brown crispy leaf tips on otherwise dark-green vigorous plants = nutrient burn, almost always from EC above the crop's tolerance. The cause is overdosed nutrient, evaporative concentration, or accumulated salts. Dilute with RO water until EC sits at the crop target, re-check pH, and no new burn appears within 24 hours.

Symptoms

• Brown crispy necrotic tips on multiple leaves at once
• Symmetric pattern — both sides of the leaf affected equally
• Leaves themselves remain dark green and vigorous
• Tip burn first on the largest fastest-growing leaves
• Slight leaf curl downward on edges
• No interveinal pattern, no spotting [OSU-NUT-01]

Cause

Nutrient burn is osmotic damage at the leaf margin where the transpiration stream concentrates and dehydrates leaf tip cells. The trigger is solution EC pushed above what the crop can handle. Three failure modes dominate. First, the grower follows a generic recipe at full strength when the specific crop needs 60–80% of label. Second, evaporation concentrates the reservoir — a 40 L tank can lose 5 L per week in dry indoor conditions, pushing EC up 12% without any nutrient added [OSU-NUT-01]. Third, top-ups with concentrated nutrient instead of plain water gradually drift EC upward.

Diagnose

The single most useful diagnostic is to measure EC and compare to the crop's known tolerance — lettuce 0.8–1.2, tomato 2.0–3.5, strawberry 1.2–1.8 [UCD-LET-01]. Differentiate from calcium tip burn (inner enclosed leaves, normal EC, low RH/airflow) — nutrient burn hits exposed older leaves at high EC.

Fix

1. Measure EC and compare to crop-specific upper bound.
2. Calculate dilution: if EC reads 2.0 and target is 1.4, replace 30% of reservoir volume with RO water.
3. Top up with RO or distilled water until EC hits target. Stir thoroughly before re-reading.
4. Re-check pH — dilution drops buffering capacity, and pH often drifts. Re-adjust to 5.8–6.2.
5. For severe cases (EC > 2× target), drain the reservoir completely and mix fresh at target EC.
6. Trim burned tips for cosmetic reasons only — they will not regrow but the damage is contained.

Prevention

Measure reservoir EC every 2 days; weekly is too slow in dry environments. Always top up with plain water until EC returns to target, then add concentrated nutrient only if EC is below target — never the other way around. Replace the reservoir every 7–10 days regardless of EC reading; trace element drift accumulates even when bulk EC looks fine [GROWER-LOGS]. Run new crops at 70% of label strength for the first two weeks; ramp up only after observing zero tip burn.