Soil pH And What It Means To Your Plants

Soil pH is a measure of the acidity and alkalinity in soils. pH levels range from 0 to 14, with 7 being neutral, below 7 acidic and above 7 alkaline. Although ever plant, including turf grass, requires a particular pH range in order to take full advantage of the nutrients available in the soil, the optimal range for most plants is between 5.5 and 7.0.  Just like our bodies, each nutrient plays an important role in a plant’s health. If the soil pH falls outside of this range, a plant’s heath and growth will be less than optimum.

Soil pH 101

Getting Soil Tested For pH

The first part of the process is finding out your soil’s pH. This can be done using a testing kit or soil probe purchased at your local garden center, or by submitting a soil sample to an accredited lab or local extension service. The most thorough method is through a lab or Soil pHextension service. These results will usually also show the nutrient make up of the soil and how to improve it.

A list of soil testing labs is available at this link: Soil Test Labs.

How To Take A Good Soil Sample

A good soil sample is required for testing. Simply use a clean hand trowel (stainless steel is preferred), insert it into the soil to a depth of around 3”-4”, insert it again at angle in order to get a slice of soil. Next, remove any grass blades, stems, thatch stones and other organic matter from the sample. Fill the sample bag up to the fill line.

Some Favorite Plant pH Requirements

Each plant has its own requirement of what pH range is ideal  for it. Some plants, such as asparagus, prefer a pH closer to neutral or even a little alkaline. Others, such as azalea, prefer soils more on the acidic side. The chart below shows the optimal pH ranges necessary for some favorite plants and turf grass species.

Soil pH

How To Adjust Soil pH

Your soil tests have come back from the lab and your soil pH is not in the optimal range for what you want to grow. What do you do? That depends on the results.

If the pH is too acidic (low), you can add lime to the soil to make it less acidic. The test results should indicate just how much lime to use to get it in an acceptable range.

If you are growing acidic loving plants and the pH came back too high, you will need to add sulfur to the soil. Sulfur is used as either elemental lime or aluminum sulfate. Again, the test results should indicate just how much lime to use to get it in an acceptable range.



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