Pines

• Pines are typically easy-care landscape trees, preferred as specimen or accent trees and as borders or windbreaks for large yards. They require minimal fertilizer and need little pruning. Thorough soil preparation before planting is the surest route to success with pines, which have very deep taproots and are harder to influence with later changes to the soil. Pines benefit from thick mulch applied above their root zones, to conserve soil moisture.
  
  

Acidic Soil

• Pines are fairly adaptable conifers that grow in all parts of the United States, though not all species do well in every locale. Each pine has its own particular requirements, though most do well in fertile, well-drained soils. In general, evergreens do grow better in soils that are acidic. Nutrients that are present in the soil and applied in fertilizers may be unavailable for the tree's use when soil is too alkaline. Get a reliable soil test done to find out how alkaline or acidic your soil is, and whether you need to add specific nutrients.
  
  

Adding Sulfur

• Rapidly lowering the pH of alkaline soils is difficult, and can't be done permanently in high-calcium soils. Adding elemental sulfur to the soil is the temporary solution, especially if there are already pines in the ground. Encouraged by soil warmth and moisture, soil microbes transform elemental sulfur into sulfuric acid, which neutralizes alkalinity. Using iron sulfate is another option, and is quicker. Either way, the effect is temporary. Soil pH rises again once soil bacteria exhaust the sulfur supply, so repeated applications are required. Using too much sulfur, or using it too frequently, can injure or kill plants. Consult with a local Master Gardener to get specific guidelines for your area.
  
  

Soil Conditioners

• Soil can be acidified organically with the addition of large amounts of acidifying organic matter such as peat moss and composted oak leaves. Popular organic fertilizers, such as cottonseed meal and fish meal, are available in bulk, and help acidify the soil as they break down. These changes typically longer-lasting.
  
  

Mulch

• Also consider the long-term soil acidifying potential of the mulch you apply. In a natural forest pine needles, twigs, bark fragments and other forest duff accumulate on the ground as natural mulch. This acidic forest layer slowly decomposes, returning nutrients to the soil where microbes break them down for reuse. Mulching with pine needles-starting with the ones that fall every year-as well as pine bark and other acidic natural mulches, can alter soil pH over time and also steadily feed the trees.