Lime on the Lawn: Find the Right Products

Fast-Acting Lime May Be the Best Choice

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A soil test that measures pH should determine springtime applications of lime. (c) Peter Anderson, Getty Images

Got low pH in lawn soil? If so, you may be on a path to grass frustration and failure. 

When pH is correct, plants are better able to access soil nutrients. Turfgrass, for instance, lives most successfully in pH 6.5 to 7.0. When soil pH is lower, grass can’t readily take in what it needs. The problem is costly. We can waste fertilizer applications on soil with pH too low for turfgrass.

Apply lime after getting a soil test.

 It will recommend the amount of lime. In this article, we'll look at several types of lime. (See this map of the U.S. depicting areas dominated by acid soil.) 

How to choose lime:

1. Different types of lime. 
The most common horticultural products are calcitic lime or dolomitic lime. Both raise pH, but calcitic lime also increases soil calcium (Ca). Dolomitic lime increases both calcium and magnesium (Mg), with the emphasis on magnesium. If a soil test shows a deficiency in either mineral, choose lime accordingly. If there is no Ca or Mg deficiency, either lime can be used--but dolomitic lime is often less expensive. Both forms are compatible with organic growing. 
 

Hydrated lime, also known as builder's lime or slaked lime, is sometimes sold for lawns, but this practice raises some questions. According to Penn State Center for Turf Grass website, hydrated lime products "can cause turfgrass burning; they also stick to shoes and can be tracked into homes or other buildings.” Hydrated lime is not compatible with organic growing. 

2. Different lime formulations. 

Manufacturers package lime in pulverized, pelleted, granular, and liquid forms. Turf professionals often use liquid lime, but keep in mind that they have professional spray equipment. All dry forms can be distributed with a drop-spreader.

Many homeowners prefer pelleted or granular lime because it is less dusty than pulverized.

But pellets, while easier to work with, are slower to deliver lime's benefits. It can take as much as 100 days for conventional pelleted lime to dissolve and begin its work. 

Fast-acting lime is a pelleted formulation that combines the best characteristics of pulverized and pelleted lime--and offers a few more benefits besides.  Fast-acting lime costs more per pound than conventional, but the material goes about four times as far and works faster. Where you need 10 bags of conventional lime, you need only two of fast-acting lime. 

These products boost pH in about six weeks, rather than the 12 to 14 months it takes with conventional lime. They are helpful in spring because they work during the current growing season. Fast-acting lime is spread with a drop-spreader, same as other pelleted products. Products such as Lightning Lime, Encap, Agway, Pennington’s, or Solu-Cal are found in garden centers and large retail chains.

“The key to rapid pH adjustment,” says John Harrison at Espoma Products in Millville, New Jersey, “is to use lime that is milled into a superfine powder prior to being pelleted.” Harrison is a spokesperson for Lighting Lime, a fast-acting product introduced by Espoma in 2015.

 “As soon as the lime pellet becomes wet, pH adjustment begins. The numerous minute lime particles come in contact with a higher number of soil particles," he says. 

Most fast-acting products rely on additional ingredients to facilitate rapid pH changes.

“We add humic acid to finely milled lime because university studies showed that it greatly increases the speed of the pH adjustment,” says Espoma’s John Harrison. 

Humic acid facilitates nutrition uptake by plants. It is a valuable addition to the soil food web. 

3. Optimal timing. 
Lime can be applied whenever the soil isn't frozen but is best in spring or fall. Many turf pros choose to split the application between the two seasons. If a test recommends 50 pounds per 1000 square feet, for instance, they might use 25 lbs. in the spring and 25 lbs.

in the fall. Fall applications have the advantage of percolating through the soil during the dormant season.

Plan of Action:

Soil with acidic (low) pH is found throughout most of eastern North America, as well as the Midwest and a few areas in the west. To improve the lawn, consider these steps:

  1. If a soil test says pH on your property is too low for a healthy lawn, follow the recommendations on the test.
  2. Consider whether a particular type of lime is needed, dolomitic or calcitic. (See point 1 above.)
  3. Decide which formulation is best for your situation, pelleted or pulverized
  4. Choose the best timing. If you want the benefits of increased pH during the current growing season, a fast-acting lime in spring is probably the best choice.