pH--LOWER

Before modifying the soil pH, make sure to have a soil test to determine the current pH.
To lower the pH (or make more acidic) by one pH point, supply roughly 15 pounds of garden or elemental sulfur per 1000 square feet, depending on soil type. More sulfur would be needed for clay soils; less for sandy types. Incorporate the sulfur into the soil or spread on top of the ground. Water
well.
It may take a year or two for the soil pH to reflect the change.
The use of pine needles and peat moss will also acidify the soil, though it is difficult to state accurate amounts needed.
See: pH , pH -- Raising , pH Plant Requirements.