Denver Tree Service: Landscape Freeze Injury and What You Can Do
Colorado trees and plants are severely damaged as a result of April cold. Some damage in Denver, Fort Collins and along the Front Range is just becoming apparent. Effects may last through the 2013 growing season.
The arctic cold events were sudden, unprecedented and sustained. Temperature records dating back to 1872 were broken. The April 8 high temperature of 71 degrees was 11 degrees above normal. On the night of April 8, the mercury plummeted nearly 50 degrees to 22. There was no recovery on April 9 as the record low maximum temperature of 22 was recorded. The low that night was a record of 9 degrees. The high on April 10 was just 23 degrees and the low that night was a record low of 6. On April 16 the 22 degree low temperature tied the record. Finally on April 22 the low of 21 was a record breaker.
During winter dormancy plant cells are protected from freezing by increasing the concentration of natural “antifreezes” such as sugar and glycerol. In spring, the cells become turgid as leaf and flower buds swell. Spring is the most critical and vulnerable time for outdoor landscape plants.
Plants normally unfazed by spring cold snaps including pines, spruce, junipers and arborvitae were damaged.
During the April freezing weather, ice crystals formed within plant cells disrupting membranes. Cells suddenly lost dehydration. Foliage, flower and twig mortality ensued. The severity of the damage differs with plant species, genetics, age of the plant and hydration prior to the cold weather. In some cases just the foliage was frozen. In more extreme cases the twigs and branches were also frozen.
Plants cannot repair damaged tissues – plants only replace. Damaged leaves, flowers and twigs will be shed by the plant.
Some plant material has begun to recover. New leaves are forming from the secondary buds. However, some of the foliage is damaged and distorted. The replacement growth may not be as durable. Chlorosis (yellowing) and/or early leaf drop later in the summer should be expected.
WHAT YOU CAN DO
Step 1. Call Swingle to schedule a visit with a Landscape Care Consultant to evaluate the trees and plants causing you concern. Swingle has offices in Denver and Fort Collins and serves the Colorado Front Range.
Step 2. Based on the condition of the plant and your expectations, we will recommend:
Removal of damaged plants and provide new plant recommendations.
Fertilization: Foliar spray fertilization – 1 application. This special application is designed to increase the quality and vigor of ornamentals damaged by extreme cold temperature. An additional application may be completed in 14-21 days. If successful, results may be expected within 2 weeks. Your consultant will return in July to re-evaluate the plants to determine if your landscape has recovered or needs further recommendations. The fertilization may or may not improve the aesthetics or health of your plant. We can NOT guarantee it will be effective. If a removal and replacement is necessary, we will apply the cost of the fertilization application towards the removal and/or replacement by Swingle.
Allow plant to recover on its own. Schedule a mid-June consultation to see if pruning or removal is necessary.