Diagnosing Dahlia Decline: Fertilizer Burn, Watering, and Fungal Issues

Brown leaves and buds on dahlias indicate one of three problems:

1. Fertilizer burn (synthetic fertilizer on dry plant).
2. Too dry between waterings.
3. Fungal issues in wet, cool weather.

Stop fertilizer. Water deeply (soaker hose 1.5+ hrs) and wait until soil is dry 3″ down. Spray Serenade (organic fungicide) if fungus suspected. In hot 90s, judge by soil moisture—clay/organic soil holds water longer. Deep soaking encourages deep roots.