Pine trees come in a variety of species all within the conifer group of plants. Different species have varying sizes of cones and needle shapes. They are identified by the shape and number of slender needles in the needle bundle. Pine trees require a slightly acidic soil to prevent the development of disease.
A soil test determines the pH level of the soil you wish to plant the pine tree in. Soil tests are available in most garden centers. Soil tests are also provided through most university extension services for a small price. The pH determines the acidity or alkalinity of the soil. Tests grade pH on a scale of 1 to 13. Soils with a pH below 7 are acidic, while soils above 7 are alkaline.
Elemental Sulfur and Iron Sulfate
Acidifying soil requires the application of elemental sulfur to the soil. Sulfur is a slow-acting element and takes between three to four months to take effect. Iron sulfate is also available to acidify the soil. Iron sulfate is messy to apply, leaving rusty marks on clothing and property.
Cotton meal seed and ammonium sulfate also lower the pH of soil for pine trees. Water-soluble fertilizers are available that keep acidity at the same level, which are applied according to the packaging instructions. These level off soil pH, but will not lower the acidity. Cottonmeal seed is added as a fertilizer substance. Ammonium sulfate is also added as a fertilizer but will burn plants if added in too large a quantity.
Materials to lower soil pH are added to the soil according to the pH test results. Lab tests from a university usually recommend application rates. Application of elemental sulfur is temporary but effective. Sulfur is never applied at rates higher than 5 to 10 pounds of sulfur per 1,000 square feet, says the University of Florida website. Plants require regular monitoring to determine that the sulfur is being applied at the correct rates and at the right time.
The soil area requires well-draining soil. When planted, a good amount of soil should be transferred with the roots to prevent drying. Allow the sulfur enough time to take effect in the soil before planting. Take soil samples before planting and test using a pH testing kit right before planting to check the soil acidity. Determine the best soil acidity according to your specific pine variety.