Soil pH

• The acidity or alkalinity of soil is referred to as its pH. A low pH -- below about 6.5 -- is generally considered to be acidic. A pH of about 7.0 is neutral and anything higher is alkaline. Acidic soil occurs in areas all over the country, and is one of the problems most commonly faced by gardeners.
  
  

Causes of Acidic Soil

• A number of factors can lead to soil being acidic. The decay of plant matter over time naturally leads to acidic soil, and the parent material of soil also plays a role. Soil that was formed from acidic rocks or minerals like granite, for example, will be more acidic than soil formed from limestone. Increasingly, acid rain is also a cause of acidic soil.
  
  

Solutions

• Incorporating crushed lime into soil is the most common and effective way to fix acidic soil. Lime raises pH by neutralizing acid. Calcitic agricultural lime and dolomitic agricultural lime are two materials specifically used as soil amendments. Alternative liming materials, such as ground oyster shells and wood stove ash, are also useful, but must be used in higher quantities. If you have alkaline soil and need to make it more acidic, incorporating organic materials like peat moss will acidify the soil over time.
  
  

Plants for Acid Soils

• If you have acidic soil, another solution is to simply choose plants that thrive under these conditions. Blueberry bushes, azaleas, flowering dogwood trees, sugar cane and many pine species grow well in acidic soil. Most garden vegetables, however, prefer neutral to slightly acidic soil.