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Seeing brown, silver or dead needles on your conifers? Have you been told by an arborist that your trees or shrubs have “freeze damage”? Read on for an explanation – and steps to take going forward to assist your landscape in recovering.

The recent 2014 event began on November 10, 2014, with a high temperature of 64 degrees (recorded at the Denver weather station). By the night of November 12, the (record low) temperature was -13 degrees. This represents a 77 degree change in temperature – the 3rd largest drop ever recorded in Denver since 1872.

What happened to the trees during this short but devastating drop?

As day length shortens and temperatures cool, landscapes prepare for winter. Certain processes prepare plants and trees for winter by storing nutrients and generating leaf shed. These winter preparation processes were not complete at the time of the November sudden drop – and the plant cells of outdoor trees and shrubs simply froze. Consider what occurs when a hose or pipe full of water is left exposed to a hard freeze – water expands as it freezes, and bursts those hoses and pipes. This same process occurred in many of our unprepared landscapes: our trees and shrubs’  vascular tissue simply burst.

Trees and shrubs majorly affected:


freeze damage to foliage of a juniper

freeze damage on juniper foliage. image by CSU Extension

Austrian pine
Ponderosa pine

Deciduous Trees

Cottonwood – primarily hybrid
Elm – select species
Maple – select species


Manhattan euonymus
Burning bush
Privet – Lodense, and Golden Vicary; Cheyenne appears unaffected

What to do going forward? According to certified arborist Steve Geist:

  • check with your certified arborist to determine the extent of your freeze damage.
  • ask for your trees and shrubs to be inspected for:
    • fungal cankers attacking weakened and dead branches
    • Bacterial wetwood in cottonwoods and elms
    • elm bark beetle
    • ash bark beetle
    • any problems with conifers, as freeze-damaged conifers have lost three to five years’ worth of needles, and will need several years to fully recover.



Need help identifying freeze damage? We offer free plant health care evaluations and prescribe a prioritized course of treatment for damaged trees and shrubs!

Call us at 303-806-TREE or click to schedule your free plant health care consultation today.

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