pH is a measure of how acidic water or another substance is. As the illustration shows, pH ranges from 0 to 14 where 7 is neutral. pH of less than 7 indicates acidity while pH over 7 indicates the substance is more alkaline or basic. The pH level of your lawn will dramatically affect the overall health of your grass. Optimal pH levels for your lawn are between 6.0 and 7.0.

The most common causes for acidic soil that we see are heavy rainfall which washes away nutrients and acidic parent material which just means the soil is made from acidic substances to begin with. You should think about liming your lawn when you see these symptoms:

1. Fertilizer isn’t working

Fertilizer typically won’t work properly when soil is too acidic because the nutrients from the fertilizer won’t be adequately absorbed.

2. Your soil is sandy

Sandy soil needs to be treated with lime more frequently because it contains less calcium and magnesium than a soil higher in clay and organic matter. Sandy soil also allows water to move through more rapidly and washing away nutrients.

3. Your grass is yellowing

Low pH levels inhibit the availability of nutrients to grass and your lawn will start to yellow indicating a lack of nutrients. A benefit of lime treatment is that your grass will become greener.

4. Weed infestation

If you have noticed an increase in the amount of weeds in your lawn, it may be because your soil is acidic. Unfortunately common and more aggressive weeds tend to thrive in acidic conditions.

5. A test shows your lawn’s pH level is below 6.0

You can measure the pH level of your soil yourself with a simple device like this that can be found at your local hardware or garden supply store. For more extensive testing, you can also take a soil sample to a local Cooperative Extension office where they can analyze it for free or for a small fee. Once you know what elements are lacking in your soil, then it will be easier for you to determine the best time for applying lime or if lime is the right treatment for your soil.

Lime is an essential component of a healthy soil and lawn. Applying lime regularly to your lawn is beneficial because it allows for more efficient nutrient absorption. In the Pacific Northwest, it is common for soil to be more acidic which makes lime an essential treatment for your lawn to help neutralize the Ph.

Wait Until Late Spring to Apply Lime

The best time to apply lime depends on your climate, soil type, and the type of lime you are using but in general, the best time to apply lime to your lawn is in the late spring. You should wait until late spring or early summer to begin application because this is when grass begins growing more quickly as temperatures start rising. Late spring and summer provide optimal conditions for grass growth and therefore make it easier for the composted material coming from lime applications to be taken up by the plants efficiently. In addition, these warmer months result in increased microbial activity which helps organic material breakdown more quickly into usable nutrients that promote healthy growth in plants over time.

Choose the Right Type of Lime

There are two types of lime: calcitic lime and dolomitic lime. Calcitic limestone is made from calcium carbonate, while dolomitic limestone contains both calcium carbonate and magnesium carbonate. Most store bought lime treatments will be dolomitic lime that are more fast acting and work great for most lawn’s needs.

Test Your Soil

As noted above, before adding any fertilizer or amendments to your lawn or garden, it’s important to test your soil first in order to determine its specific needs. Generally the best practice to get an accurate test result is to take samples from at least 3 different areas in your lawn. Then combine your 3+ separate samples into a single large sample so that your results reflect the state of your entire lawn, not an isolated area. Getting a representative sample is important whether you send the soil to your local Extension office or perform a DIY test at home.

Lime takes time to break down the soil and affect the pH. Working with a professional lawn care company can ensure that your lime treatment is applied correctly and safely. Lime powder can be harmful when inhaled, if you are using powdered lime, be sure to follow precautions and wear a proper respirator mask like an N95 to protect your lungs. Lime pellets are often easier and safer to work with than powder and masks are not needed. A spreader is the best tool to distribute the lime evenly over your lawn’s surface. For best coverage, apply half the recommended amount walking vertically then apply the rest walling horizontally. Water lightly after application to help the soil absorb the lime.

When applying lime products, ensure you follow the recommended application amount. Under-application will have minimal or no effect long-term but over-application should be avoided as well. In extreme cases, excessive fertilizer can runoff into nearby water sources and pollute the water. In residential use, more commonly excess lime is left on paved surfaces or plastic which causes erosion. Be sure to keep lime away from plants that thrive in acidic soil like blueberries and azaleas.