Thursday, June 19, 2014

Dealing With Winterkill

All right it’s the middle of June and some plants did not survive this past winter and others have been damaged; it’s called “winterkill”. 

Winterkill is often used to describe loss of field crops such as alfalfa, rye and winter wheat.  This year it’s being used to describe damage to bushes, trees and perennials in the Midwest.

Large amount to evergreens have turned rusty colored brown.  This was due to a combination of extreme cold being pushed by strong winter winds.  Calm cold usually doesn’t kill – it’s the wind that cinches the death and damage.  Combine that with two summers of drought conditions and it can be a deathblow.

Conifers and evergreens such as American Yew, arborvitae, pine, spruce, hemlock and others all have suffered noticeable damage.  The reason these are damaged more than deciduous trees (they loose their leaves) is they loose moisture through their “leaves” on sunny days.  When the ground is deeply frozen, they can’t take up more moisture to replace what’s lost.  Foundation evergreens will suffer more because they also get the hot reflection off the siding. Evergreens and conifers planted close to roads will often die on the street side because they have been hit with splashed or windblown salt spray.
Winterkill on holly bush.

Check the trunk of deciduous trees to make sure there was no rabbit damage.  They can girdle an entire trunk, which will kill a tree,  Deer damaged trees may survive if only branches and tips are ate. 

At this point, if your shrub or tree is completely brown, it’s probably not going to come back.  Try scratching the bark and if it’s green underneath, it may still be alive.  Alive may not actually mean you have a good-looking tree because evergreens do not typically send out new branches to replace lost.  They may start growing at the top and according to where it sits, that may be good enough.  I think it’s safe to say it will never look the same.  Also, a severely damaged tree will be susceptible to disease and insect damage over the next several years.

If your shrub or tree has only branches damaged, it’s safe to remove that branch if there are no sprouts showing.  Let nature cleanse your evergreens if only the tips or some needles show brown.  Remember:  white pines routinely have loss of needles and that particular loss isn’t deadly.  If they are putting on new candles, they are surviving. 

After you decide to remove a dead or severely damaged shrub or tree, check out varieties that are resistant to winter kill.  Don’t plant where they will be subject to long periods of warm winter afternoon sun or salt spray. 

Most experts don’t advocate anti-desiccant sprays because they are too labor intensive and seldom really work.  Wrapping a shrub in burlap may help as well as putting up windbreaks.  Don’t cover in material that will hold winter heat during the day as that will cause it to think it’s spring and the new growth will be. Killed.

(Middle) "Blue Hosta" stunted this year.

(Middle) Blue Hosta where it is healthy and thriving.
We’ve also seen some significant winterkill on hosta.  I lost some and others seem stunted.  Right next to this is a totally healthy and thriving hosta.  Experts can’t explain why or how this happened in this way.  I’m doing the “2014 wait and see”.  I’m not digging where there was once hosta and I’m hopeful there will be something in the ground waiting for next year to again reappear.

It’s a pretty good bet if your roses show no growth whatsoever, they are dead and should be removed.

Japanese maples, flowering dogwood and Japanese flowering cheery cultivars are usually only hardy to -20 degrees.  If your trees were saved, it’s because they were sitting in a microclimate.

On the other hand, some of my perennials, trees and bushes have never been more healthy or thriving.

Enjoy this beautiful June 2014 – it’s been a bonus after a tough winter. 

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