pH is measured on a scale from 1 to 14. The lower the pH the more acid is the soil and the higher the pH the more alkaline is the soil. A pH of 7 is neutral. Most garden plants prefer a pH of neutral or just below neutral.
What is the result of a too high pH?
Most of the micro-elements (trace elements) are unavailable at a too high pH.
Plants grown in a soil with a too high pH often shows yellowing of the young leaves.
How do you lower a too high pH?
We use lime sulphur to lower the pH.
How do you raise a too low pH?
Dolomitic lime is incorporated into the soil before planting in order to increase the pH.