Hydrated Lime

Gardeners use lime to increase the pH of soils, making them more alkaline or sweet and less acidic or sour. Alkaline soil is typically found in dry climates, while acidic soil is associated with wet climates. Ground limestone — calcium carbonate sold in garden supply centers as garden lime — is most often used to adjust soil pH, but you can also use hydrated lime, or calcium hydroxide, which is more finely ground and more caustic.