Espoma Organic Soil Acidifier (30 lb) Review

Our Verdict

This is the standard home-garden route to lowering soil pH, and the reason to read the label rather than a rate you found elsewhere is arithmetic. Colorado State's guideline for ELEMENTAL sulfur is about 650 lb per acre to move pH one unit — roughly 15 lb per 1,000 sq ft. Espoma's own label asks for 12 lb per 100 sq ft for the same one-point reduction, which is about 120 lb per 1,000 sq ft, or eight times the extension figure. Both are right for what they describe: CSU is dosing pure elemental sulfur, and this bag is a blend of elemental sulfur and gypsum. Carry the extension number onto this product and you will apply roughly an eighth of what the label asks for and conclude the amendment does not work. The label also carries the same texture correction the lime guidance does — 15 lb rather than 12 on heavy clay — which is the buffering that makes clay resist a pH change in either direction. Two honest deductions. Espoma does not publish a guaranteed analysis on its own product page, so the sulfur percentage that would let you reconcile the two rates is not available without the bag in hand, and for a product whose entire function is a chemical rate that is a real gap. And none of it matters at all if your soil contains free lime: do the vinegar test first, because in calcareous soil this bag is neutralising carbonate rather than moving your pH, and CSU's word for that attempt is impractical.