pH is a measurement of the acidity or alkalinity of your soil. It is determined by the amount of lime (calcium) contained in your soil, and the type of soil that you have. In general, British soils range from about pH 4 to pH 8. (The word pH is a boffins term, it stands for “potential Hydrogen ions”). As well as affecting your soil acidity, it is worth remembering that lime is the fourth most important plant food.
Why is it important?
Some plants are very sensitive to soil pH. Probably the best known examples of this are (the majority of) Rhododendrons and heathers which will not tolerate lime in the soil. On the other hand are Clematis and Daphne, which prefer a lime soil.
It is not generally known however that many plants are sensitive to pH levels. The plant pH preference lists will help you to see which plants prefer to grow at particular pH levels. For many plants a deviation of 0.5 is permissible, and several will grow at deviations of 1.0.
How pH affects plant foods
Finding out your pH
Raising your soil pH - to make the soil more alkaline
Lowering your soil pH - to make the soil more acid
Types of lime explained.
Plant preference lists - for different pH levels