Spruce trees growing on one's lawn have the unexpected side effect of lowering the pH level of the soil beneath them, effectively raising the acidity of the ground. Certain grasses will find this change difficult to handle. This change in acidity can inhibit your others plants' biological processes and they may be unable to grow.
All soils are classified scientifically by their density, texture and acidic levels. The pH levels in soil is influenced by the chemical make up and can change depending on the substances that come in contact with the material. While some plants will grow well in alkaline soil, others need more acid. Typically grass seeds require a balance between the two, or a neutral pH, to effectively grow and develop.
The pH scale ranges from 0 to 14, with 7 being neutral. The lower the pH, the more acidic the soil, while the higher the pH, the more alkaline. A soil's pH levels will affect a plant's ability to successfully absorb nutrients and water from the ground. Without proper hydration and nutrients, a plant will become unable to continue its natural biological processes and will die.
Spruce trees are evergreen trees whose needles will lower the pH level of the soil as they decompose. As the soil pH levels fall, grasses and plants within the area begin to lose their ability to absorb nutrients and slowly degrade. Symptoms include browning leaves and poor growth rates even with proper fertilization and hydration of the soil.
Imbalances in pH levels can be corrected by the addition of lime to the soil. Liquid or powder lime is available at most gardening centers and will gradually increase the alkaline nature of your soil. Manufacturer guidelines should always be followed when applying lime to one's garden as plants and the environment as a whole will suffer from improper use.
Spruce trees will attract various wild life and pests to the surrounding areas. Certain birds and squirrels build their nest within the pines of spruce tress, and deer often feed off of the seeds found within the pine cones. Pests like spider mites and aphids, along with fungi, are attracted to the tree and can spread to other plants within the garden.