The basic needs for plant life are air, water, sunlight, and nutrients. These nutrients are utilized in many different metabolic and physiologic functions. They are needed in various amounts and come from a variety of sources. Under ideal growing conditions, the local environment provides a plant with all the nutrients in sufficient quantities to grow and thrive. Oftentimes, trees growing in urban areas are in less than ideal growing conditions and supplemental nutrition is necessary.
There are two types of nutrient supplements for plants in the landscape - ones that are applied as part of a maintenance program, like regular fertilizer applications, and ones that are applied to correct a specific deficiency. Nutrient deficiencies can show up in many ways. Yellowing foliage, chlorosis, tip dieback, and lack of vigor are common symptoms and can be clues as to what nutrient the plant may be lacking. While specific nutrient deficiencies can be determined by symptoms alone, a soil test can help with confirmation and diagnosis.