Almost all of our ‘outside’ apple trees (planted in the ground with no permanent shelter) get a winter wrap with a white tarp to keep out the worst of the winter cold. We expect a certain amount of tip die-back (winterkill) on even these protected trees in cold winters, but the tarp helps a good deal. Once the spring sun begins to warm things up during the day it is important to vent these tarp-tents by opening up the tops to moderate the temperature. Our more tender or long-season apples are housed in permanent coldframes and these get vented as well to prevent heat build-up in the spring. Sometimes they also get shade-cloths hung on the south and west sides. All of this is geared to prevent the trees from breaking bud too early and having tender tissues when temperatures are still falling below zero at night. When dormant, our apples can tolerate -40°C, but tender growth can only take a few degrees of frost and blooms can be damaged at -2°C. Once flower buds are the size of a pea ensure your tree doesn’t drop below freezing – if a cold night looms throw a sheet over the tree to keep it safe. Once fruit is set, a few degrees of frost is tolerable. Ensuring your tree is well-watered as spring comes on is also important to a healthy transition.
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Notes from the Nursery
At Canada's most northerly nursery John and Kim grow and experiment with fruit trees and local material.