Mature Tree Care

Updated: Sep 21

Learn procedures specific to a routine maintenance program for mature tree care, including tree inspection, mulching, fertilization, pruning, and tree removal.

Tree Inspection

Regular tree inspections can catch changes in a tree’s health before a disease, insect, or environmental problem becomes too serious to address. Ideally, mature trees should be inspected at least once a year to assess four characteristics of tree vitality: new leaf or bud formation, leaf size, twig growth, and absence of crown dieback (gradual death of the upper part of the tree). Growth reduction is a fairly reliable cue that the tree’s health has recently changed. An experienced arborist can look at twig growth from past years to determine whether there is a reduction in the tree’s typical growth pattern. Further signs of poor tree health are trunk decay, crown dieback, or both. These symptoms often indicate problems that began several years before. Loose bark, deformed growths, and conks (mushrooms) are common signs of stem decay. Any abnormalities found during these inspections, such as insect activity and/or spotted, deformed, discoloured, or dead leaves and twigs, should be noted and monitored closely. If you are uncertain about what to do, report your findings to your local ISA Certified Arborist or other tree care professional for advice on treatment options.

Mulching

Mulching can reduce environmental stress by providing trees with a more moderate root environment that has fewer temperature and moisture extremes than the surrounding soil. Mulch reduces competition from weeds and grass and prevents mechanical damage by keeping lawn care equipment away from the tree’s base. Mulches made from plant matter, such as shredded leaves, pine straw, peat moss, or composted wood chips, will add nutrients to the soil as they decompose and help improve overall soil biology. To be most effective, mulch should be placed 2 to 4 inches (5 to 10 cm) deep and cover as much of the root system as possible. (Roots can extend as far as 2 or 3 times the diameter of the branch spread of the tree.) When placing mulch, care should be taken not to cover the actual trunk of the tree. A mulch-free area around the base that is 1 to 2 inches (2.5 to 5 cm) wide is sufficient to avoid overly moist bark conditions.


Soil Management

Soil management is another important aspect of mature tree care. Urban landscape trees often exist in soils that lack the nutrients, pH (acidity or alkalinity), drainage, or pore space (air and water space) needed for growth and development. Proper fertilization based on plant needs can correct many deficiencies that limit growth. Sometimes soil nutrients may be sufficient, but soil pH levels may prevent plant uptake. In this case, soil amendments, such as sulfur, lime, and even some mulches, can alter soil chemistry and help alleviate plant stress. Drainage systems or grading can help correct saturated soil conditions, although trenching or earthmoving activities within the tree’s root zone may cause more harm than good. Compacted soils can be tilled mechanically or with compressed air to increase porosity and encourage root growth. Care must be taken when loosening soil under the drip zone to avoid root damage. When dealing with a mature tree that provides considerable benefit and value to your landscape, it is worth the time and investment to have the soil tested for nutrient content and texture. An arborist can arrange to have your soil tested at a soil testing laboratory and recommend treatments based on the results.

Pruning