Coffee Grounds, Vinegar, Pine Needles and Eggshells Barely Shift Soil pH

… more less Used coffee grounds are near-neutral (~pH 6.2–6.8); fresh pine needles (pH 3.2–3.8) decay to near-neutral; microbes consume vinegar's acetic acid within days. Whole eggshells are CaCO₃ but too coarse to react; only fine powder acts like lime.