PEGSMOR is an acronym used to help arborists explain the different stages of tree care management a tree may go through.

Trees do go through several stages of development during their lives.

  • Planting
  • Establishment
  • Growth
  • Structure
  • Maturity
  • Over Maturity
  • Replacement

PEGSMOR AND Care of Maturing Trees

Urban foresters use the concept of PEGSMOR to understand the needs of a tree over its lifespan. PEGSMOR stands for planting, establishment, growth, structure, maturity, over-maturity, replacement.

Planting: 0-2 years

Tree must be planted evenly with the topsoil. This is a huge mistake in tree planting with most trees planted too deeply.

[hs_form id=”6″]

Mind over head electrical wires and structure. Tree species is not a commodity so plant the best tree you can afford. Mature transplants need to be handled with care.  Structural pruning to establish main leader or trunk for the tree.

Water in the winter is very important. Also remove guying, the stakes, in this stage.

Establishment:  2-5 years

Structural pruning will establish main leader or trunk for the tree.

Growth: 5-10 years

Tree is growing but has not reached the desired height of the primary branches.

  1. Prune every three years and remove deadwood, eliminate weak crotches and remove interfering branches.
  2. Water during dry periods; “winter water”.
  3. Replenish mulch and keep grass away.

Structure: 10-20 years

Tree is tall enough to select the primary and secondary branches that will be the main structure throughout the tree’s life.

  1. Prune every three to five years and for most trees remove deadwood, selected primary and secondary branches,  weak crotches, and interfering branches.
  2. Winter water.
  3. Replenish mulch.

Maturity: 20-60 years

  1. Tree develops its full crown and width. Growth dramatically slows during the upper end of this stage and will remain in this stage until it declines.
  2. Prune every three to five years depending on species and environmental events/stress.  Remove deadwood, interfering tertiary and quadrinary branches and weak tertiary and quadrinary branches.
  3. Winter water.


Tree is declining faster than it is growing.  Primary and secondary branches begin to rot and die back becoming defective.  Root flare may also become defective.

  1. Prune every three years and for most trees remove deadwood and stabilize/remove defective branches.
  2. Monitor structural stability.
  3. Cabling and Bracing are tree preservation strategies as well as integrated pest management.

Replacement: at or before death of prior tree

Tree has declined to the point of being totally unsound or primary branches have been pruned to the point where the tree does not have a viable structure.  This stage is needed to finish and subsequently continue to the cycle. Tree canopy must be added at a 1:1 ratio. So if you remove a tree, urban foresters plant a tree.  It’s better to plant a tree where it’s needed not in a bad spot in your yard. The net cooling effects of maintaining and strategically planting new trees,  allow canopy growth to occur on a metro wide area.

  1. Remove the tree, grind stump.
  2. Replace the soil and plant a new tree.