Tomato Yellowing Then Browning: pH, Fertilizer, or Water Diagnosis

Yellow-to-Brown Tomato Leaves: Not Just Overwatering

Leaves turning yellow, then brown and crispy—especially if drying up rather than wilting—suggests pH imbalance or fertilizer toxicity, not excess water (which causes yellowing with limp texture).

Diagnostic Checklist

Immediate Safe Actions

1. Test soil pH (target 6.2-6.8 for tomatoes)
2. Flush containers with 3× volume water if salt crust visible
3. Apply balanced organic (4-4-4) at half rate if deficiency suspected
4. Remove crispy leaves—won't recover, reduce disease risk

Soil Replacement Caution

"New soil around roots" risks further root disturbance. Better: top-dress 1 inch compost + worm castings, water in. Roots grow into it naturally.

pH and EC meters ($15-20 each) eliminate guesswork. Test before treating.