How and When to Apply Lime | Lawn & Grass Health

April 12, 2010 | by Fred (email) |

We’re well into the Spring season here in central Maryland, and we’re getting focused on our lawns. In the past, we’ve told you about targeting lawn weeds and when to apply weed and feed, how to prevent crabgrass, and how to choose a garden spreader that’s right for your needs.

Up this week: lime, and specifically: why, how, and when to apply lime to your lawn.

If your lawn is yellow, has dead spots, or just lacks a uniform, green luster, lime may be right for you. Read on for details.

What is Lime?

Lime (a.k.a. Garden Lime or Yard Lime) is pulverized limestone. The primary active ingredient is calcium carbonate (CaCO3). Most liming agents will be at least 95% calcium carbonate, unless you are purchasing lime combined with another product, such as a fertilizer (this is unusual).

Why Apply Lime to a Yard?

You should apply lime to a yard that has a low pH (a.k.a. acidic). Grass will struggle to grow in acidic soil, and lime raises the pH of the soil to a level more suited to grasses (and less suited to, say, mosses, which can thrive in more acidic soils). As a positive side effect, lime also provides calcium to plants, a key nutrient for growth.

What Causes Soil Acidity?

Acidity in lawns can be caused by many things. The soil in your area can be naturally acidic. Some fertilizers will lower the pH in a lawn. And, most notably in deciduous forests, decaying oak leaves will raise the acidity of the lawn each Fall.

In order to determine how much lime to apply to your lawn, you’ll need either a soil test kit, or you’ll need to call a professional. In some areas the local agricultural school will do a soil test for you (Todd @ Home Construction Improvement has an article on this one). We recommend not spreading lime unless you’re certain your lawn requires it, as highly alkaline soil is no better than an acidic soil for growing grass.

Once you know your lawn’s pH, you can consult the bag of lime for the proper amount that should be spread to bring up the pH to the recommend level (between 6.5 and 7.0).

When to Apply Lime?

Lime can be applied year round. We recommend applying it in the early spring, and then again mid-Summer if a test shows it is warranted. Moderation is key, as over-liming a yard will product negative results due to high alkalinity.

Most granule-type limes (called fast-acting limes) will be absorbed into the soil with the first 1/4 inch rain fall. Larger limes can talk longer to dissolve and seep into the lawn and may take several rainfalls or watering applications to fully absorb.

Lime can be applied along with a fertilizer or week killer and will not negatively impact the effectiveness of these products.

How to Apply Lime?

Any type of garden spreader works great for applying lime. We prefer a broadcast spreader to gain even coverage, but a side-effect of this type of spreader is that it’s harder to control next to flower beds.

When applying lime, this is less of a concern since most flowers will also thrive in a more balanced soil, but can be a concern for other products like weed and feed.

Where to Buy Lime?

Lime can be purchased at any local nursery, and is available at most of the big box stores, including Home Depot and Lowes. Expect to pay around $20-25 / bag at the big boxes, which will typically cover 5000 square feet for a moderately acidic lawn.  Lime will also be applied by professionals if you decide to choose a lawn service.  Our pal Amy over at GreenGardenista offers some excellent advice on lawn service pros and cons and advice on choosing one at that link.