Are you seeing dead needles appear on the outer edges of your cedars? This could be symptomatic of winter damage to cedars. Instead of pruning in spring, fertilize the trees with landscape tree food, then apply liquid feeder to the foliage daily during April and May. At some point in June, evaluate any winter damage that may be present. You can do this by scratching the stems of the cedars to see if the tissue beneath is green. Prune back any branches where the tissue is brown. Cut back each branch to healthy stems with green tissue. Once you have removed winter damage in trees and shrubs, prune the cedars to shape them. Voila!
SOURCE:http://www.gardenoholic.com/how-to-repair-winter-damage-on-cedar-trees/