Like any plant in your yard, trees require a complex suite of nutrients to thrive. Only some of these nutrients are produced via photosynthesis, the rest must be available in the soil. 

1. Weak Growth  

Weak growth from a lack of fertilizer can come in several forms. The most common is stunted or slow growth on young trees, as these have the shallowest roots but the highest nutrition needs. In some cases, a tree may respond to a lack of nutrients by putting out suckers around the base of the tree or up the trunk in an effort to produce more leaves for collecting nutrition from the sun. Fertilizing can help make the growth much more robust.

2. Discolored Leaves

Leaves can discolor at any time during their growth cycle due to a nutrient deficiency. Your tree service can even use the hue and pattern of the discoloration to pinpoint which nutrients are deficient. Yellowing foliage, for example, is commonly a sign of nitrogen deficiency. Nutrient-related discolorations can range from solid yellow to spotting in shades of black, brown, red, or yellow. In some cases, only the leaf veins or the margins discolor.

3. New Leaf Issues

Tender young leaves should be bright in color with a glossy surface. If the color is more yellow than green or if the color seems dull, then fertilizing is needed. The leaves may also come in small and stunted, with few reaching their fully mature size. Deformity on new leaves is also common if there is low nutrient availability, but fertilizing each year in early spring should solve the problem. 

4. Root & Tip Dieback

Growth becomes inhibited when there aren't enough nutrients available. Calcium in particular affects root growth, and the tips of new roots will dieback if there isn't enough available. A weak root system leads to poorly anchored trees that are unable to absorb enough water from the soil. Branch tips may also begin to wither due to a lack of nutrients in the soil, as well as in response to the shrinking root system. 

5. Premature Leaf Loss

Deciduous trees drop leaves in the fall, while evergreen trees may experience the bulk of the old leaf loss in the spring, summer, or fall. If a deciduous tree loses leaves out of season or an evergreen is losing leaves and needles without replacing them, then there may be a nutrient deficiency. Magnesium is often to blame when leaves fail to thrive, but verify that there are no other concerns, such as disease or drought causing premature leaf shed.

Contact a tree and lawn care service to set up a tree fertilization schedule suitable for your landscaping.