Use our calculator to determine how much material you'll need
When gardeners talk about "lime" or "limestone," they mean either calcium carbonate (calcite or calcitic limestone), or calcium-magnesium carbonate (dolomite or dolomitic limestone). Of the two forms, dolomite is preferred as it provides magnesium as well as calcium. Both are mined from open-pit quarries, then crushed and screened to the appropriate particle size. Our calculators refer to either of these materials.
Other forms include true lime (calcium oxide), and slaked, builder's, or hydrated lime (calcium hydroxide). True lime is highly caustic making handling for gardeners not worth the trouble. Hydrated lime is sometimes sold to home gardeners, but it has more neutralizing power than limestone meaning you should apply about two-thirds the recommended amount. It is less caustic than true lime, but is powdery so awkward to apply.