Winter Damage to Evergreens
Winter Damage to Evergreens
The damage to evergreens that we are seeing this spring is "winter kill" or "winter burn." The brown spots on the tips of evergreens are dieback due to a combination of things. Winter burn results from water loss in plants during the winter. During the growing season, water is absorbed from the soil into the roots and pumped throughout the plant. Lost water during the growing season is quickly replaced as the roots continue to absorb and pump water from the soil into plants. Because evergreen plants retain their foliage, transpiration, and loss of water continue during the winter. Roots in frozen soil have no ability to replace the lost water and, winter burn occurs as needles desiccate, die, and turn brown.
Salt damage can also be a problem for evergreens. Salt applied to sidewalks and roadways can also contribute to winter burn.
Recovery of evergreens from winter burn depends on the extent of the damage, healtht, and viability of the plant. Wait until later in the spring before doing any pruning. It is possible that parts of a tree or shrub that looks dead now might still have surviving buds. Those buds may green up and fill in the brown areas.
Prune back the dead parts of the plant if they do not green up. Branches should be pruned back to a live bud.
Following is a list of suggestions for dealing with winter burn in specific evergreens:
Evergreens with no latent (dormant) buds on stems
Evergreens that have no new growth buds along the stem will not produce any new green growth except at branch tips (if they are alive). Burnt needles will not recover and only growing tips may put out new green growth.
Prune out entire dead branches.
All of the brown needles will fall off, with new growth only occurring from the branch tips.
Pine, Fir, Douglas fir
New needles will flush out only from the candles at the tips of the branches if the tips are alive. Pine will hold needles for a few years before they drop all the dead ones.
Evergreens with latent buds on stems
Although winter-burned needles will fall off, evergreens with healthy existing latent buds, the growing points along the stems, will be able to grow new needles.
To help prevent winter burn in the future:
Keep evergreens properly watered throughout the entire growing season until the ground freezes.
Maintain a 3-4" layer of organic mulch around evergreens to help retain soil moisture throughout the growing season. As this mulch breaks down, it will also improve our soil's moisture-holding capacity
Protect young evergreens in highly exposed sites during winter with burlap, snow fencing, or other materials to protect from sun and wind.
Water evergreens consistently throughout the growing season until the ground is frozen.