Yes, over-fertilization can occur if Plumeria receives an excessive amount of nutrients. Over-fertilization can lead to salt buildup in the soil, causing root damage and inhibiting the plant’s ability to absorb water and nutrients properly. This can result in leaf burn, wilting, and overall decline in plant health. To avoid over-fertilization, carefully follow the manufacturer’s instructions for the fertilizer being used. It’s better to slightly under-fertilize than to risk causing harm to the plant. Regularly flush the soil with water to help leach excess salts from the root zone.