Why does your Petunia hybrida Trilogy have yellow leaves? Diagnose the cause and fix it with our step-by-step guide.
Nitrogen is a mobile nutrient in Petunias; when levels are low, the plant moves nitrogen from older leaves to new growth, causing uniform yellowing of mature foliage. This often occurs after heavy flowering periods where the plant has depleted soil nutrients.
Petunias require well-draining soil; excessive moisture saturates pore spaces, depriving roots of oxygen and causing chlorosis. This leads to a pale yellow appearance often accompanied by wilting even when the soil is wet.
If the soil pH rises above 6.5, iron becomes chemically unavailable to the Petunia. This results in interveinal chlorosis, where leaf veins remain green while the rest of the leaf tissue turns bright yellow.
A lack of magnesium can cause yellowing between the veins, often appearing as blotchy patches on older leaves. This is common in container-grown Petunias where leaching from frequent watering has depleted minerals.
Your plant might also be experiencing one of these issues:
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