The best time to prune dead limbs on blue spruce evergreens is in the spring, when new, light green growth appears. Dead limbs should be removed with a hand saw or pole saw 1 inch from a green shoot to encourage vigorous growth.
The blades of the saw should be wiped with a mixture consisting of 7 cups of denatured alcohol and 3 cups of water before pruning. This prevents the transfer of any fungus or disease. Blue spruce evergreens should not be pruned from August through October due to an increased risk of fungal infections through the open cuts.