Lime is usually added in winter for annual crops, such as vegetables, just prior to digging, as the lime can take effect over the winter months and will not damage young growth.
Before planting perennial plants like lawns, shrubs, fruit or trees, apply lime if the soil is acid. To find out how much lime is required you need to check your soil pH.
Lime applied to the surface, around established plants for example, can take years to have any effect, so adjusting pH before planting or sowing is recommended.
A soil pH test measures the acidity or alkalinity of the soil. A pH 7.0 is considered neutral. Above pH 7.0, the soil is alkaline and below pH 7.0, the soil is acid. See our page on soil pH testing for more detail.
It is especially worth checking soil pH and making any adjustments before designing or planting a new garden, making vegetable plots, planting fruit or when growth is disappointing.
Testing can be done at any time, but if carried out within three months after adding lime, fertiliser or organic matter, the test may give misleading results.
If your soil pH test comes back at 7.0 or higher, you have alkaline soil, and liming is not necessary. If the pH is above 6.5, or if you wish to grow acid-loving ericaceous plants, you may wish to reduce the pH by adding an acidifying material.