Which fertilizer type is beneficial for annual flowers in their planting hole?

The inclusion of slow-release fertilizer in the planting hole for annual flowers is beneficial because it provides a steady supply of nutrients over an extended period. This gradual nutrient release aligns well with the growth needs of annual flowers, which may require consistent feeding throughout their blooming cycle.

Slow-release fertilizers are designed to break down over time, allowing plants to absorb nutrients as needed rather than being overwhelmed with a sudden influx. This helps prevent issues such as nutrient burn, enables healthier root development, and supports sustained growth and flowering.

The other options are not as optimal for this specific application. Fast-release fertilizers, while providing immediate nutrients, can lead to rapid growth that may not be sustainable over time and can increase the risk of nutrient burn. Liquid fertilizers generally offer quick results but require more frequent applications, which may not be practical for established plants. Organic compost is excellent for improving soil structure and enhancing its nutrient content, but it may not deliver the immediate nutrient availability that annual flowers benefit from during their crucial early growth stage.