If you have tried to improve the quality of your lawn or garden but have not seen the result you expect, it may be time to check your soil's pH. The pH of your soil is important because it affects nutrient availability to plants. If your soil's pH is out of balance, no amount of fertilizer is going to improve the health of your plants until you correct the underlying issue.
The first step to diagnosing if you have an issue with pH is to have a soil test. It is best to never guess what your soil's pH may be, but to let the soil test tell you the pH of your soil. You can send your soil sample to a lab using an at-home soil testing kit or take your sample to your local cooperative extension office. From there, you can begin to correct any pH imbalance that may exist.
What is Soil pH?
pH is the measure of acidity or alkalinity of a solution. You soil's pH is measured on a scale from 0 to 14, with 7.0 considered a neutral pH. Many plants and turf grasses grow best in soil with a pH range of 6.0 to 7.0.
If your soil's pH falls outside this ideal range, the health of the plants you are growing may be negatively impacted. Outside the optimum pH range, the plant cannot use certain nutrients that it needs, leading to unhealthy plants.
Correcting the pH of the soil makes the nutrients in the soil, and any fertilizers you may add, more available to the plant for use. Soil amendments can be added to help correct the pH levels back to the ideal range.
Some plants like Azelas and lilac grow best in soil that is more acidic or alkaline so it is best to know what type of plant you are planning to grow and the ideal pH range for that particular plant before you begin to modify your soil's pH.
Correcting Your Soil's pH
ph less than 7.0: Soil with a pH lower than 7.0 is considered acidic. Acidic soils, also referred to as "sour" soils, are typically found in rainy, wet climates. While acid-rich soil may be suitable for certain plants like blueberries and azaleas, it is not ideal for all plants.
To raise the pH level of acidic soil to an ideal range, lime is often added. Your soil test may also recommend a calcitic lime, which is also known as agricultural lime, or a dolomitic lime. Dolomitic lime contains both calcium and magnesium, and is beneficial for soil that is also magnesium deficient.
ph greater than 7.0: Soil with a pH higher than 7.0 is considered basic, or alkaline. This type of soil is also sometimes referred to as a "sweet" soil, and is typically found in dryer climates. Some plants like lilacs prefer a more alkaline soil, but as with soil that is too acidic, many plant do not thrive in soil that is too basic.
A soil acidifier, gypsum, or sulfur product is often added to lower the pH of alkaline soil to a more ideal range.
How much lime or sulfur you will need to add will depend on the results of your soil test and area you are treating (lawn, edible garden, ornamental landscape beds).
When Should Soil Amendments Be Applied?
Adding these amendments to your lawn or garden is best done in the early spring or fall as it gives them time to work into the soil before the growing season.
Lime is best applied just after it rains so that the lime does not wash off your lawn or garden. And while you can apply lime and fertilizer at the same time, it's best to apply lime at least 3 weeks before applying fertilizer. This will give your soil's pH time to adjust and be able to uptake the nutrients in the fertilizer, making your fertilizer application more efficient.
How to Apply Soil Amendments to Your Lawn
How you apply soil amendments will depend on if you choose a liquid or granular products, and which products you are applying. The video above shows how to apply a granular lime to your lawn.
Maintaining Soil pH
Once you have applied your soil amendment, you'll need to maintain the soil pH over time. Lime and other soil amendments slowly work their way out of the soil over time. This will require retesting your soil and applying additional maintenance applications each year to ensure the pH stays within an acceptable range.