Extension News

Spring Frost Damage to Trees

Frost damaged evergreen

Note to media editors:

Additional photos are available with this story.  Check out the release titled  Freeze Damage to Landscape Plants  also posted on The ISU Extension Web site on 5/4/05.


AMES, Iowa – The cold weather of the last week has caused some significant damage to new vegetative tree growth across much of Iowa.  Many hardwoods including oaks, ash, walnut, maples and hackberry have had their new spring growth killed by the freezing temperatures. 

Most hardwoods are very resilient. If they are reasonably healthy, their dormant buds will become active and eventually they will reform new leaves, and by mid summer if will be most difficult to see that they were damaged. Most likely, the greatest damage will be some loss of growth and a slight reduction in health and vigor because of that lost growth. If the tree was marginal in terms of health and vigor, the damage may be more significant, and in a very few cases, cause branch dieback and in the most severe cases even tree mortality.

Some of the conifers have also been affected. Most of the pines do not appear to have suffered significant damage. However, the spruces and Douglas fir have suffered the most, with significant dieback of the newly formed shoots and needles. This loss is more significant than the loss of growth with deciduous trees because conifers have fewer dormant buds.

However, most conifers will recover and may in some cases put secondary growth later this spring.  In some cases, with young trees in particular, the needle and twig loss may be sufficient to cause mortality.  Many of the conifers are also able to survive the frost damage because different parts of the tree are at different stages of growth expansion; earlier stages are more tolerant of cold conditions than later stages.

Contacts :

Paul Wray, Forestry, (515) 294-1168, phw@iastate.edu

Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, jmcguire@iastate.edu

High resolution photos suitable for printing are available through the following links.

Frost damaged evergreen

Frost damaged hardwood