Hydrated Lime This is fast acting, but does not last well in free draining soils. It is very effective to produce a fast change in pH level, and suitable for all types of heavier soil. It is also the “strongest” form of lime generally available, and some sensible precautions should be taken to keep it out of your eyes and off exposed skin. Sensitive skin may be at risk of irritation or burns. Ground Limestone. This is natural limestone which has been ground to a powder. Its speed of effect and persistence in the soil will depend on how finely it has been ground. Generally it is less strong than hydrated lime, needing about 30% more to raise the pH by the same amount. It is also usually cheaper than the hydrated lime, and because it woks more slowly and lasts longer, it is more suitable for use on light sandy soils. Ground Chalk This is very similar to ground limestone, though it is often more readily available in some parts of the country. Mixed Lime This is usually sold under a brand name. It contains a variety of particle sizes so it will give some immediate effect then go on for a long period. The strength is usually between hydrated lime and grounds limestone.

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How pH affects plant foods  | Finding out your pH |  Raising your soil pH  | Lowering your soil pH | Types of lime explained.  | Plant preference lists

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