Soil pH is a measurement of acid and alkaline within the soil and is measured on a scale from 0 to 10.
7.0 pH measurement is neither acid or alkaline and is referred to as neutral soil
Measurements below 7.0 pH are acidic soils
Measurements above 7.0 pH are alkaline soils
In horticulture, the measurement of 6.0-7.0 pH is known as slightly acidic to neutral pH This is the measurement that the majority of plants used in UK gardens and landscaping projects will happily grow and thrive.
Some plants such as Rhododendron and Azalea will only grow in soils with a good acidic pH
Some plants like Lavender and Geraniums need soils with good alkaline pH.
0 – 3.9 = very strongly acid
4.0 – 4.9 = strongly acid
5.0 – 5.9 = moderately acid
6.0 – 6.9 = slightly acid
7.0 = neutral
7.1 – 7.9 = slightly alkaline
8.0 – 8.9 = strongly alkaline
9.0 – 10 = very strongly alkaline