Understanding Soil pH

Successful gardening requires a minimum understanding of soil chemistry. pH levels are used to measure acidity and alkalinity in substances, including soil. Certain plants require specific soil pH ranges to do well, and knowing what pH levels mean can help you choose the right solutions to get that soil into the right range for your garden’s needs.

Successful gardening requires a minimum understanding of soil chemistry. pH levels are used to measure acidity and alkalinity in substances, including soil. Certain plants require specific soil pH ranges to do well, and knowing what pH levels mean can help you choose the right solutions to get that soil into the right range for your garden’s needs.

In organic chemistry, pH stands for potential of hydrogen. This essentially means a measure of how strong or weak the hydrogen particles are in a given solution and how their activity can affect the acidity or alkalinity of the solution—although that’s more trivia fodder than anything you need to remember. What you should know is that the pH of a substance is ranked on a scale of 0 to 14, with 0 being acid, 14 being alkaline and 7 being neutral, or balanced.

You don’t need to be a chemist to check your soil pH. Fortunately, today’s technology does most of the difficult part for you. You can find soil pH test strips at any home and garden store, and checking soil pH is as easy as mixing soil with distilled water and inserting a strip. The strip will change color based on the reaction it has with the soil, and you can match the color to the chart included with the test kit to determine the pH level.

For most plants, a soil pH level between 6.0 and 7.5 is ideal. This is a range between slightly acidic to slightly alkaline. Many garden soils naturally fall within this range, and correction is only necessary if the pH levels are beyond either end of this range.

If your soil falls outside the acceptable pH range, adding compost or other organic matter will help to neutralize it. If you need to make the soil more acidic, sulfur can help to lower the pH level. On the other hand, if you need more alkaline soil, add lime to raise the soil pH. Fertilizers generally make soil more acidic, and this is why over-fertilizing can “burn” plants.