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How to test your soil pH


In order to get the best out of your garden plants and crops, it’s worth testing your soil pH. In the UK this ranges from 3.5 (strongly acid) to 8.5 (strongly alkaline), with 7 being neutral. Most fruit and vegetables prefer soils that have a neutral to slightly acidic pH.

The availability of nutrients, such as calcium, potassium, iron and magnesium, is influenced by pH. In addition, at a pH of 6 to 7.5 the soil organisms that break down organic matter and release nutrients are at their most active. The soil’s pH can also affect the incidence of certain diseases and cultural problems. Clubroot, which attacks brassicas, prefers acid soil, for example, while alkaline soil encourages scab on potatoes.

For a rough indication of your local soil pH, look at what grows well in nearby gardens. If camellias and rhododendrons thrive, the soil is acidic, while flowering cherries, yew and clematis prefer alkaline soils, such as those on chalk.

Testing your soil is quick and easy - simple pH testing kits are available in most garden centres.

How to do it


It’s important to choose a representative soil sample for testing. Avoid areas that have recently been treated with fertiliser, compost or other materials, as these can affect the reading. Soil pH can vary widely across a garden, so it’s best to test samples from several areas to get an accurate picture.


2 Remove any stones and twigs from your sample and place the required amount in the tube. Add the chemical solution, shake the contents, and wait until the soil particles settle. Once the liquid clears, compare it against the chart - its colour indicates the pH.


Use the results of this test when choosing which plants to grow in your garden. It will save you the disappointment and wasted effort - not to mention wasted money - of trying to grow plants that will never thrive in your soil. 


You can find out which plants thrive in acid or alkaline soil by going to our 'Plants' section. In the 'Plant search' facility you can select the appropriate soil type and you will get a list of detailed profiles on a wide range of plants that will enjoy your selected soil conditions.

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