Most gardeners really don’t understand what soil pH is all about, therefore they do nothing about soil pH and how it affects the growth of plants indoors and out. However, once you know what pH is all about and how it works, you become a vastly superior gardener and the plants under your care grow almost as if they were in Heaven.

Every plant in the world, good or bad, has its own preference for soil pH. The term “pH” simply means the potential of hydrogen in the soil. The more hydrogen, the more acid the soil. The less hydrogen, the sweeter the soil.

We use limestone in its many forms to sweeten the soil, and we use granular sulfur to make soil more acid. We don’t do anything to the soil one way or the other without first checking the pH of the soil.

Once upon a time, gardeners sent soil samples to the Cooperative Extension Service for a detailed analysis of their soil, including the pH. From there, gardeners were able to change the pH based on test results. Today, most gardeners use an inexpensive device, an electronic pH soil tester, to test the pH periodically during the year. Most nurseries and garden centers stock the instrument year-round, at a retail price around $20. As long as you don’t drop the tester, it will last a lifetime.

Testing pH with the instrument is flawless and easy. Always test after it has rained. The soil must contain some moisture if rest results are to be accurate.

Insert the metal prove into the soil its entire length and, in 30 seconds, the digital meter will read the pH. On outdoor plants, you may want to check soil pH bordering two or more areas of the plant, generally beyond the dripline or tips of outer leaves. House plants need only one check of the soil pH.
Once you know the soil pH, you can raise or lower the pH depending on needs of the plant.

To increase soil pH (in effect, making the soil “sweeter” or more alkaline), apply limestone. To lower soil pH, rely on wettable sulfur.

Now that you have a working knowledge of soil pH, we want to walk you through the different classifications (trees, shrubs, flowers, fruits) to report what the pH values are for each plant. On separate data sheets following this one, you will find the following data sheets:

* pH values for shrubs and trees;
* pH values for annuals and perennials;
* pH values for fruiting trees and berry plants;
* pH values for popular indoor plants;
* pH values for tropical plants;
* a potpourri of useful pH values.