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Evergreen PH Levels

Evergreens are generally known for their superior survival skills, maintaining their bright and colorful appearance even in the depths of winter when other plants have gone dormant. However, growing conditions can affect the health of evergreen plants just like all others. For example, many evergreens cannot withstand acidity levels higher than 7.0 on the pH scale.
  1. Effects of High pH

    • The higher on the pH scale you go, the less acidity is in the soil. Soil with a pH measuring above 7.0 is considered alkaline or basic. Highly alkaline soil affects the way evergreens can absorb nutrients through their roots, which can lead to serious problems with the plant. The inability of the roots to absorb nutrients, most notably iron, from the soil results in stunted growth, since the new growth does not receive enough nutrients to really branch out. You may also notice the leaves, spines and other foliage of the plant turning yellow instead of the characteristic green; this is another indicator of foliage lacking nutrients.

    Evergreens for High pH

    • Some evergreens are more tolerant of high pH than others. In general, arborvitae plants and junipers can withstand alkaline soils. Some types of pine, including the mugo pine and ponderosa pine, as well as the black hills spruce tree, will also withstand the higher pH. These plants will show little to no negative effects from alkaline soil.

    Soil Testing

    • Before taking any steps to change the pH in your soil, you should conduct an official soil test. These tests are available from garden centers, nurseries and extension services. Follow all instructions, as different tests may require different methods. In general, you will pick up soil from different parts of the your plant area and send it into the lab to be analyzed. The analysis will indicate the soil pH, as well as other information such as any nutrient deficiencies you may have. Many times, the results will also include suggestions for correcting problems in your soil.

    Lowering Soil pH

    • The product needed to lower the pH in your soil depends on how much you need to lower it. For small changes, such as from 6.8 to 6.5, use fertilizer that contains sulfur urea or ammonium sulfate. The change will be almost immediate. Aluminum sulfate will have a similar effect, but should not be used on any evergreens from which you eat, as it can cause aluminum poisoning. Straight gardening sulfur will cause significant shifts in pH, but can take a number of months to work as the bacteria in the soil turn the sulfur into sulfuric acid. With any of these products, follow all instructions and warnings, as the amount you need will vary by your soil's pH, as well as the size of the area you need to change.