Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=229932
Story Retrieval Date: 3/6/2015 2:03:20 PM CST
Winter’s harsh temperatures froze more than our toes and left their mark on local evergreens.
Those brown patches show signs of winter damage and salt burn. While many will recover from the damage, Tim Johnson of the Chicago Botanic Garden says some of those damaged extensively will die.
Since evergreens don’t shut down over the winter, they continue transpiration, the process of releasing moisture from their foliage. When the ground freezes solid, as it did this winter, evergreens can no longer take in water, even though they are still releasing it.
A way to help protect against this is to make sure evergreens receive lots of water in the fall before winter sets in, so their roots can store it up, said Doris Taylor, plant information specialist at the Morton Arboretum.
Another cause of damage this winter was the extreme use of salt to counter the icy conditions. Salt piles up on the streets, which in turn is kicked up onto the trees, resulting in salt burn, said Johnson.
In deciding if a plant or tree is dead and should be removed, error on the side of caution. “Let them have more time if there’s any doubt about whether they’re dead or not,” said Johnson.
“It’s more of a waiting game,” said Taylor. Don’t be hasty to pronounce a tree or bush dead, it may just need a little more time to recover. Even after you've long given up hope, your evergreen may shoot out new branches or buds and surprise you.
A good way to check a plant or tree for life is to scratch the stem, said Johnson and Taylor. If the stem is green or whitish, then it is still alive. If it is brown or ashen, it is already dead.
If it is apparent parts of the plant or tree are definitely dead, cut those away so the plant can begin new growth.
Many people question if fertilizer can help their struggling plants and evergreens at this date. “Hold off on the fertilizer,” said Taylor.
Get a soil test first; you may just be wasting your time by fertilizing. At this time of the year, plants and trees “really want to rest more rather than sending out new growth,” said Taylor.
A continuing lack of moisture this spring could negatively affect evergreens trying to recover. If there is little or no rain, Taylor recommends watering trees to help them through their recovery process.