When you are purchasing seeds or new plants to put into your garden, you might notice labels indicating the pH level of soil in which the plant is most likely to thrive. What exactly does this mean, and why is it important to track the pH level in your soil?

Basically, pH is a measure of the acidity or alkalinity of your soil. The pH values for plant growth typically fall relatively close to neutral values, but there are some plants that prefer soil to be slightly more acidic than others. This is especially true for rhododendrons or azaleas, but many plants have their own preferences with regard to soil pH.

The pH scale runs from 0 to 14. A pH that reads below 7 is considered more acidic, while a pH above 7 is considered more alkaline. A reading of 7, then, is indicative of a neutral soil.

The pH influences the availability of some of the most essential nutrients for plant life found in soil. Most crops are capable of growing in soils that range from 6 to 7.5 (slightly acidic to slightly alkaline), and most garden soils in North America tend to fall in that range. However, there are some plants that prefer more acidic soil. When dealing with these acid-loving plants, gardeners are capable of lowering the soil pH by mixing elemental sulfur into the soil a year before planting the acid-loving plants.

In general, though, most plants will not like a soil pH that falls below 6, and will find it intolerable. If you’re dealing with a naturally acidic soil, you can get it closer to neutral by incorporating materials like ground limestone, which is mostly calcium carbonate and magnesium carbonate.

Determining your soil’s pH level

You might be wondering, then, how exactly you figure out the pH level in your soil. There are several different types of soil pH testers, including indicator test strips, chemical colored dyes and electronic meters. With each of these methods, you take a mixture of soil and water, or a solution provided by the pH tester, and then test the water.

With dyes, you mix them with soil water, and the resulting color gets compared to a chart that shows you the pH level. Test strips are slightly more advanced versions of litmus paper—you place the strips into the soil water and get a reading based on the color. The electronic meters are the most technologically advanced method of determining soil pH. You insert a probe into the soil water, and can then read the pH directly from a display on the meter. This is the most convenient option, but you’ll need to first make sure you’ve properly mixed your soil water.

For more information about the importance of pH levels in soil and the best methods of testing your soil pH, contact Soil Advocates at admin@soiladvocates.ca or 289-221-0164.