Passion fruit trees prefer slightly acidic soil, with the optimal soil pH range being 5.5 to 6.5. Within this range, the roots of the passion fruit can better absorb nutrients, promoting healthy growth. If the soil is too acidic (pH below 5.5) or too alkaline (pH above 6.5), it may affect the development of the plant, such as excessive acidity leading to stem base rot, which requires lime adjustment. When planting, it is recommended to choose loose, well-drained sandy loam soil, and maintain a slightly acidic soil environment by adding materials like leaf mold or sulfur powder.