Understanding Acidic Lawns

• Although many gardeners think to care for and feed their lawn, they sometimes forget that the health of their turf is directly related to the soil in which it is planted. The acidic levels of your soil greatly affect how strong and vigorous your lawn grows. Just as with all other plants, grass prefers a certain type of soil and will look sickly and eventually die if not given that soil. If your turf is looking less than its best, take a little time to test your garden soil and amend it, if necessary.
  
  

Checking Soil pH

• When you test your soil's pH, you're taking a measure of the soil's alkalinity or acidity. This is easily accomplished with a soil test kit available at gardening centers and hardware stores. Follow the manufacturer's directions carefully. If the soil's pH level is above 7.0, the soil is alkaline; if it is below 7.0, the soil is acidic. For most grass types, a pH level of between 6.0 and 7.0 is preferred.
  
  

What Causes Soil to Become Acidic?

• When potassium, calcium and magnesium leach from the soil, it becomes acidic. This may happen if there is a lot of rain that washes nutrients away, or if you apply nitrogen fertilizers frequently. If your tap water is acidic, your garden soil will also eventually become acidic when you water your lawn. In addition, if you allow organic matter--like leaves--to sit and decompose on your lawn, the soil may also become acidic.
  
  

The Consequences of High Acidity

• When soil becomes too acidic, it is difficult for your grass to absorb the nutrients it needs, including nitrogen, potassium, phosphorus, sulfur, calcium, molybdenum and magnesium. When the grass cannot get these nutrients, it loses color, becomes less vigorous, has trouble recovering from drought and heat and may become more prone to disease.
  
  

How to Correct the Problem

• If you find your soil is too acidic, the most common way to resolve the problem is to apply lime to the turf, following the packaging instructions carefully. (Lime products for grass are available at gardening centers.) Lime is full of calcium or a combination of calcium and magnesium, which aids the soil by neutralizing the acid in it.
  
  The best time of year to lime your turf is in the spring or fall, on a cool day. Applying lime when it's warm out may result in a burnt lawn. Do not fertilize at the same time you apply lime.