Diagnosing White Spots on Tabernaemontana holstii: Sunburn or Magnesium Deficiency?

Two Likely Culprits

Large white areas on leaves can result from:

1. Water droplets acting as magnifying glasses if you water during sunny hours. The droplets focus sunlight, burning small spots.
2. Magnesium deficiency—common in heavily watered, fast-draining soils where nutrients leach out.

Identifying Magnesium Deficiency

• Green veins with yellowing between them (interveinal chlorosis).
• Leaf tips/edges may curl upward, turn brown and crispy.
• Older leaves affected first, progressing upward.
• Soil pH below 6.4 locks out magnesium; ideal range is 6.5–7.0.

Quick Fix for Magnesium

Sprinkle 3 tablespoons of Epsom salts (magnesium sulfate) on the soil surface of a 16-inch pot and water in. For smaller pots, use 1 teaspoon per 4-inch pot. This replenishes magnesium and can also stimulate flowering.

Preventive Measures

• Water at the base of the plant, not over the foliage, especially in bright light.
• Use a balanced fertilizer with micronutrients, applied at half strength monthly during active growth.
• Monitor soil pH if possible.

Addressing both watering technique and nutrition should restore healthy green foliage.