By Richard Jauron, Greg Wallace
Winter is just around the corner, and while evergreen trees are built to survive the cold weather, they still need care and preventive measures during the colder months of the year. What are the best suggestions?
Here are some tips from Iowa State University Extension and Outreach horticulturists on how to help evergreens survive winter. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.
Some of the needles on my white pines have turned yellow and begun dropping to the ground in the last few weeks. Are the trees dying?
The loss of needles is probably due to seasonal needle drop. Deciduous trees, such as maple and linden, drop all of their leaves in fall. Though it largely goes unnoticed, evergreens also lose a portion of their foliage (needles) on a yearly basis. Seasonal needle drop on most evergreens occurs in fall. Needle loss is most noticeable on white pines.
As much as one-half of the needles on white pines may drop in early fall. Seasonal needle loss is less noticeable on spruces, firs and other pines, as they retain a higher percentage of their needles. Seasonal needle drop is uniformly distributed throughout the inner part of the evergreen. The oldest needles are shed. The needles turn uniformly yellow or brown and drop to the ground.
I planted several pine trees this spring. How long should I continue to water the trees?
The roots of trees continue to grow until the ground freezes. If the weather is dry, continue to water the newly planted trees until the soil freezes in winter.
How do I prevent rabbits from browsing on my small evergreens in winter?
The most effective way to prevent rabbit damage to trees and shrubs in the home landscape is to place chicken wire fencing or hardware cloth around vulnerable plants. To adequately protect plants, the fencing material needs to be high enough that rabbits won’t be able to climb or reach over the fence after a heavy snow.
In most cases, a fence that stands 24 to 36 inches tall should be sufficient. To prevent rabbits from crawling underneath the fencing, bury the bottom 2 to 3 inches below the ground or pin the fencing to the soil with u-shaped anchor pins. It’s best to have the protective materials in place by early to mid-November. After a heavy snow, check protected plants to make sure rabbits aren’t able to reach or climb over the fencing. If necessary, remove some of the snow to keep rabbits from reaching the trees or shrubs.