Will our evergreens recover from the harsh winter?
We've noticed in the past two years many of our evergreen bushes and trees getting more brown areas than in past years. This year, a 20 foot pine tree that's been there for a decade appears to be going totally dark red, we're hopeful that it's not dying, just preparing to drop a ton of needles.
Are you seeing mass dieoff in Washtenaw County due to the cumulative effect of two harsh winters? Is there anything that can be done at this point to save these bushes / trees? Could we have done something different to prepare them for a harsh winter?
Washtenaw County Michigan
Because of the severity of the 2013-2014 winter and the 2014-2015 winter, there are many woody ornamentals in Michigan that are dead or severely damaged. Some of these plants are rated for a cold hardiness for Zone 5. That means they can only tolerate winter temperatures that go no lower than -10 to -20 degrees. Both winters, there were multiple times that winter temperatures went to -25 to -28 in Southeast Michigan.
There was a good deal of outright damage during the first winter and that damage did not repair. Last winter built on the damage and more things or bigger areas or marginally damaged plants got worse. Example: boxwoods and many other evergreens. That includes both broadleaf and narrow leaf evergreens.
If needles are brown (or dark red), they are dead. They cannot ever turn green again. Right now, if there was any life left in the tree or shrub, there would be some tiny new green growth visible. But that still does not point to a recovery.There may be so little regrowth that the tree or shrub never looks good again.
When it gets colder than the tree or shrub can endure, rigid cell walls in the plant explode. It could be many or it could be a few. There is no recover from this kind of devistating damage.
The only thing that is possible is to make sure plants are well watered before the ground freezes in the fall. If the plant has enough moisture inside of it, it has a better opportunity to survive. But if it is colder than Zone 5 and the plant is zone 5, it cannot do much for that.
Covering or wrapping things in burlap does not help because this is not like putting a coat on a dog. The plants generate no heat so the only thing that it helps with is drying winds. But when the temperatures plummet, the wind is not blowing.
There are many plantd damaged all over Michigan. If you want to wait to see if marginally damaged plants recover, you can. But the completely brown pine appears to have left the planet.