This study investigates the effects of Ammonium Polyphosphate (APP) fire retardant on the combustion dynamics and flame spread rates of forest litter, specifically Pine needles (Pinus Roxburghii) and Ashoka leaves (Monoon Longifolium). Experiments were conducted to assess the influence of moisture content by preparing samples in both oven-dried and naturally dried-states. A vertical ignition setup was employed to measure flame spread rates in a controlled environment. The findings indicate that higher moisture content significantly delays ignition and reduces flame spread rates, with oven-dried samples exhibiting faster combustion. APP-treated samples demonstrated a marked delay in ignition and significantly reduced flame spread rates, with complete or partial inhibition of char oxidation and smoldering combustion. The study highlights the critical role of moisture content and fire-retardant treatments in managing combustion dynamics in forest litter, which is essential for wildfire management strategies.