Bougainvillea Brown Spots: Overwatering in Cool Weather

Fungal Leaf Spot from Wet Foliage + Cool Nights

Brown spots that kill leaves on bougainvillea in winter are typically fungal, fueled by irrigation that leaves foliage wet overnight in cool temperatures.

Immediate Changes

• Stop overhead watering; use drip or base watering only.
• Water only when soil is dry 2–3 inches deep.
• Remove and destroy spotted leaves.
• Apply copper fungicide if spread continues.

Result

New growth in spring will be clean if moisture management improves.