In November 2014, Colorado experienced the third largest temperature drop ever recorded in Denver history. This weather event was localized from the Castle Rock area and northward – to possibly Longmont. Experts are still identifying freeze damage across the Front Range and are unsure just how far east in Colorado the damage has spread. The temperature drop in Fort Collins was less dramatic, leading experts to believe this area will not experience as much damage. Arborists within the tree care industry have already starting seeing damage to Colorado landscapes, specifically to trees and plants. Yet it’s still unknown what further damage can be seen with the arrival of spring.
On November 10th, 2014, the high was 64 degrees, and then rapidly dropped to a record low of minus 13 on November 12th – a 77 degree drop in temperature. This large temperature drop follows others recorded in the state’s history: February 1951 saw the greatest decrease at 80 degrees, January 1961 came in second at 78 degrees. Prior to the November freeze temperatures were consistently on the rise.
Outdoor plants depend on a gradual cooling through the fall – alerting plants to harden off for the winter months. During this time, plants increase the sugar content of their cells, allowing them to prepare for freezing temperature. Due to an unusually warm fall, many plants had not completed this process before the freeze hit. The result was quite severe – landscape damage when plant cells flash froze and burst. Experts know when the freeze occurred, many plants and trees still had foliage on their branches and had not fully hardened off for winter.
“While we are seeing signs of freeze injury on evergreen trees, injury and damage will be found on more plant material as spring progresses. I predict we will see both short and lingering long-term landscape effects from this weather event,” says Swingle’s Senior Consulting Arborist Steve Geist.
Initially, experts thought landscapes would not be negatively affected until the spring of 2015. Only a few weeks after the freeze hit, damage became evident. The south sides of spruce and pine trees turned a bleached, straw color and junipers turned bronze. Shrubs, fruit trees, and especially roses have also shown signs of freeze damage, with brown, shriveling twigs. Brown leaves clinging to trees may also indicate damage. Further damage includes:
- Evergreens – Early, rapid freeze events can catch many plant species off guard. Pine and spruce trees are displaying the most noticeable effects of this early freeze. New growth on these tree species may be brown or even dead. Spruce and pines rely heavily on the most recent three to five years of foliage. While many recover from freeze damage by putting on new growth, the previous foliage is often damaged or lost.
- Leafy Deciduous – Many deciduous leafy trees and shrubs have retained their foliage this winter. This is a result of the leaves being flash frozen before they had fallen off. These brown, dry leaves are expected to drop during the growing season as trees put on new growth. Fruit trees may show individual twig dieback.
- Shrubs – Shrubs throughout the area are also showing signs of freeze damage such as brown foliage and twig dieback. Most shrubs are expected to recover from these damages with minimal long-term effects. Meanwhile some shrubbery may have more extensive damage with individual canes and / or complete stem dieback. Most severely damaged shrubs include roses, euonymus, grape holly, barberry and boxwood.
- Young Trees – Recent transplants may be completely dead as expert evaluations are showing that weaker plantings were severely damaged or even destroyed by the sudden cold. A skilled arborist can check the buds and tissue below the bark in young shoots to see if these plants are still viable.
As a courtesy to its customers, Swingle will inspect plant material as they service a property for possible freeze damage. While Swingle expects most to make a full recovery from this freeze, representatives will be visiting applicable properties to observe properties, make notes, leave recommendation and adjust programs as needed.
This is an important time for homeowners and businesses to have their properties evaluated by a skilled arborist- your local Landscape Care Consultant. Experts suggest, once a property has been evaluated, owners will need to continue watering trees and have dead twigs and branches removed. If trees or shrubs show significant damage, consult a professional to have them properly pruned.