Newly Planted Annuals Dying: Fertilizer Burn vs. Root Rot

Newly Planted Annuals Dying: Fertilizer Burn vs. Root Rot

Marigolds, fuchsias, and other annuals dying within 2 weeks of planting after fertilizer application and rain likely suffer from either fertilizer root burn or root rot (Pythium/Phytophthora).

Diagnosis

• Fertilizer burn: Roots brown/black, brittle; soil may have white crust. Caused by excessive soluble salts (e.g., 13-13-13).
• Root rot: Roots mushy, outer cortex sloughs off leaving white central stele; soil soggy.

Action

1. Pull a declining plant; test roots as described.
2. If fertilizer burn: Flush soil heavily with water repeatedly.
3. If root rot: Fungicide (e.g., Daconil) unlikely to help at this stage; replant in well-drained soil with less fertilizer.
4. Check soil moisture: Annuals need moist but not saturated soil.

Prevention

• Use slow-release fertilizer at half rate for new transplants.
• Incorporate compost to improve drainage.
• Water deeply but infrequently after establishment.

Quick diagnosis determines whether to salvage or replant.