Winterizing the Trees

Here on the Eastern slope of the Cascade Mountains, although we are zone 5, I have seen trees approved for zone 5 struggling to survive.  We are a mountainous zone 5, which means some years trees and plants for this zone will do well, and other years will be challenged.  Part of the reason may be the wide variations of temperature through out the fall, winter and spring.  As fall arrives, it is easy to be 75 degrees daytime, but have the nights drop to 25. 

In the winter it is common now, to have day time temperatures near 45-50 and night time dropping to single digits.  Spring too, is problematic in that around budding time, temperatures can vary from 45-60 with night time drops to near 20.

All of this freezing and thawing seems to have damaged the young trees, best evidenced by cracks and splits of the bark,  lack of vigor during the growing seaons and slow death of the tree.  
This year, as we came into fall, I wrapped all the trees with trunk wrap followed by trunk protectors that I found on http://www.amazon.com/ and http://www.treepro.com/  .   Some of the new trees are too small for the protectors, so for them,  I used tree wrap as well as wrapping the trees in burlap to slow wind damage both of which I found through http://www.gardeners.com/ .  You may have  luck locating them through local garden supply stores, also.

 I have yet to see if we will have better survival and more vigor.  Early summer will tell.  Some of the apple trees seem to fare better than the cherry and plums. 

Next, I added about 8 inches of mulch to each tree ring, taking care to avoid the mulch stacking against the trunk of the tree itself.  I use a mixture of wheat straw, grass clippings and sawdust.  Keeping it away from the trunk, lessens the area for harboring mice or other rodents.  The heavy collars on the trees right down to the soil help protect from rodent damage as well.

Mice can winter over in mulch often doing great damage to the tree by griddling the trunk with their teeth.  This ring of destroyed bark will kill the tree.  This is true anywhere.  My brother who lives in a more temperate climate grows bamboo, which he mulched heavily to help retain moisture in the soil.  Mice loved the hay seeds in his mulch and eventually began chewing bark.  He did suffer some losses. 

Once the trees have lost their leaves, I add a mixture of well composted manures, green sand, and calcium sulfate and iron.  With our annual rain fall, in the shadow of Mt Jefferson, we get about 9 inches of rain a year, including snow fall.  So the fertilizers do not reach the root system until irrigation starts in the spring.  In areas where rain is common, it would not be wise to do this before spring when growth starts as the tree comes out of the dormant period of winter.  It would not be wise to cause a growth spurt as you move into fall and freezing weather.  Over the next growing season, the mulch from the previous winter breaks down and adds to the fertility of the soil.  The mulch is bermed up so a ring is formed around the tree which holds the water from winter rain/snow and then irrigation through out the growing season is held in the root zone of the tree as well.  Best of all, the mulch prevents weeds.  The berm needs to be kept off the trunk of the tree.

Despite damage last winter, we had plenty  of apples from two trees and some pears.  The two cherry trees were damaged beyond salvage and one new cherry did not leaf out this spring after planting,  Perhaps because of the zone 5 schizophrenic weather.  The nursery I purchased it from, http://www.millernurseries.com/  has a guarantee and will replace new trees free.  The older cherry trees had not been protected.  So the replacements will be put into winter protection for next year after replacements arrive in the spring.