HOW IMPORTANT IS A LIMESTONE TREATMENT FOR YOUR YARD?

MML Staff_Erin H EXPERT April 13, 2008

The short answer is that it depends largely on where you live. In the eastern US and some parts of the southeastern US, the soil tends to be acidic, and limestone is beneficial. In the Midwest and West, where soils are alkaline, limestone is harmful.

Here's some background. The pH is the measure of acidity and alkalinity, on a scale of 0-14, with 7 being neutral (that's the pH of pure water). The pH of the soil determines whether soil nutrients are in a form plants can readily absorb. For most plants, the ideal range is about 6.5 to 7.5 (blueberries and azaleas are among the exceptions -- they need a more acidic soil).

Unless you've had a soil lab (preferably one affiliated with a university) test your soil pH, you can't accurately know the pH. You can pick up a soil sample kit for free at some garden centers or at the local office of the Cooperative Extension Service. You collect the sample, send it to the lab, and in a few weeks they send you the results. The cost of the test varies from state to state, but $30 is typical.

If you're talking about fertilizing your lawn instead of your garden, you have much more leeway. The main nutrient in lawn fertilizer is nitrogen, and its availability is less pH-dependent than many other nutrients. Unless the pH is very acidic (less that 5.5) or alkaline (8.5), nitrogen availability is about the same.

If your soil is so acidic that lime is necessary, it's important to follow the application rates and timing from a soil testing laboratory, because different soil types react differently to limestone. And it's not uncommon to spread the applications over a 3-year period to avoid making too drastic a change at one time.

If your lawn care company cannot explain their limestone application plan to you in great detail and in a way you understand, consider hiring a different company.