Gardening is both an art and a science. Sometimes, gardeners do different tests to learn about the condition of their soil. One thing they can test for is the soil's pH.
The pH measures how acidic or basic a substance is. It is measured on a scale from zero to fourteen. If something has a pH less than seven, like lemon juice, it is acidic. If something has a pH greater than seven, like bleach, it is basic or alkaline. A pH of seven is considered neutral.
The pH of the soil affects how well plants grow. Different plants like different pH levels. For example, blueberries like acidic soil. Lilacs like alkaline soil. Some gardeners call acid soils "sour." They call alkaline soils "sweet."